Chapter 1: Introduction

Musculoskeletal Injury in Professional Dancers: Prevalence and Associated Factors. An International Cross-sectional Study

Craig Loren Jacobs

A thesis submitted in conformity with the requirements for the degree of Master of Science Graduate Department of Institute of Medical Science University of Toronto

Musculoskeletal Injury in Professional Dancers: Prevalence and Associated Factors. An International Cross-sectional Study

Craig Loren Jacobs

Master of Science

Institute of Medical Science University of Toronto

2010 Abstract

Purpose: To determine the prevalence and factors associated with injury in professional ballet

and modern dancers, to explore dancers’ attitudes and perceptions of injury, and to assess if dancers are reporting their injuries and reasons for not reporting injuries.

Methods: A cross-sectional survey was undertaken in professional ballet and modern dance companies in Canada, Denmark, Israel, and Sweden.

Results: The point prevalence of injury in dancers is high (55% ballet; 46% modern) and most have chronic pain. Years dancing professionally and rank were associated with injury in ballet dancers. Attitudes towards injury vary and some dancers are continuing to dance when injured.

Greater than 15% of all injured dancers have not reported their injury.

Conclusions: Injury is common in dancers and there is an urgent need to investigate interventions to help control injury and understand the long-term implications of these conditions in this population.

Acknowledgments and Contributions I wish to express my sincere gratitude to my supervisor Dr. J. David Cassidy for his guidance, supervision, and scientific integrity and for providing me with such an important and exciting research opportunity. I am truly grateful to my cosupervisor, Dr. Pierre Côté, for his belief in the importance of my research. His excitement for research and science is truly infectious and inspiring. I would like to thank Dr. Eleanor Boyle for her collaboration, contributions and guidance with the statistical analysis. I am so grateful for her time, patience, and expertise. I thank Dr. Carlo Ammendolia for his invaluable insights, input, and suggestions for my work. I am so appreciative of my entire program advisory committee, each of whom has provided me with guidance and inspiration.

This was a truly collaborative international effort that would not have been possible without the contributions of Dr. Eva Ramel, Dr. Jan Hartvigsen, and Dr. Isabella Schwartz. They were instrumental in applying for the ethics board applications in Sweden, Denmark and Israel respectively. Dr. Ramel helped to develop relationships and communication with both the Royal Swedish and Royal Danish Ballets. Additionally, Dr. Ramel’s previous scholarly work regarding professional dancers has been an invaluable source of knowledge, and her willingness and excitement to discuss dance health issues with me was extremely helpful. All three collaborators reviewed the study questionnaire and made site specific recommendations. They provided me with support during the survey completion in each country. They provided supplies, helped with logistics and communication and gave me a greater understanding of social support and work conditions in each country. I am so thankful for the amount of time and energy they have contributed to this project.

Dr. Cesar Hincapié published the first systematic review of injury and pain in dancers which served as a springboard and inspiration for my study. He guided me through the best evidence synthesis systematic review update process and served as the second reviewer for all the literature. I wish to thank him for that guidance and for his contribution to my research. I would also like to thank Dr. Paula Stern for her encouragement over all these years, her role in the pilot of the questionnaire, and for starting me off on this path. My deepest gratitude also goes to Dr. Heather Shearer who has always been ready with advice and support whenever I needed it, without question. I commend and thank Monica Alder for her wonderful design of the

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questionnaire which played an integral role in its success and appeal. The staff, scientists, and students at CREIDO were so helpful over the years in so many ways, and I thank them all for their input, suggestions, and incredible help.

Of course, this work would not have been possible without the participation of the dance companies involved. I thank all the dancers, artistic staff, and administrative staff of the National Ballet of Canada, Toronto Dance Theatre, Royal Swedish Ballet, Cullberg Ballet, Royal Danish Ballet, Batsheva Dance Company and Ensemble, and the Kibbutz Contemporary Dance Company and its junior company. I would like to especially thank those individuals from these companies who facilitated the implementation and logistics of the study including Joanna Ivey, Bridget Cawthery, Lars Anderstam, Jane Salier-Eriksson, Karen Bonnesen, Yaniv Nagar, Claire Bayliss-Nagar, and Rachel Ariel.

I wish to thank all of the organizations who provided financial support for my research and graduate studies: the Canadian Institutes of Health Research, the Artists Health Centre Foundation, the University of Toronto, and the Canadian Memorial Chiropractic College. This project was also partially funded by the Centre for Research Expertise in Improved Disability Outcomes (CREIDO) which received substantial funding through a grant provided by the Workers’ Safety and Insurance Board (WSIB).

I thank my parents, Michael and Shelley, for their never ending support and love. I am so grateful to my partner Atsmon who has constantly reminded me of the importance of my work at every stage and has been an incredible source of strength, encouragement, and love.

Table of Contents

ABSTRACT...... II

ACKNOWLEDGMENTS AND CONTRIBUTIONS ...... III

TABLE OF CONTENTS ...... V

LIST OF TABLES ...... IX

LIST OF APPENDICES ...... XI

LIST OF ABBREVIATIONS ...... XII

CHAPTER 1: INTRODUCTION...... 1

1.1 Statement of Problem ...... 1

1.2 Literature Review ...... 2 1.2.1 Screening for relevance...... 2 1.2.2 Critical review of the literature...... 3 1.2.3 Characteristics of musculoskeletal injury in dancers...... 3 1.2.4 Prevalence and associated factors of musculoskeletal injury and pain in dancers...... 4 1.2.5 Incidence of and risk factors for musculoskeletal injury and pain in dancers...... 8 1.2.6 Definition of Injury...... 8 1.2.7 Injury Reporting...... 10 1.2.8 Assessment Tools for Musculoskeletal Injury and Pain in Dancers...... 10

1.3 Environmental Scan of Healthcare and Social Programs...... 11

1.4 Summary and Rationale...... 13

1.5 Primary Objectives and Research Questions...... 13

CHAPTER 2: METHODS AND MATERIALS ...... 15 v

2.1 Study design...... 15

2.2 Source population/Setting ...... 15

2.3 Inclusion/Exclusion Criteria ...... 17

2.4 Recruitment/Survey Methodology ...... 17

2.5 Description and Pilot-Testing of the Questionnaire ...... 18 2.5.1 Description of the study questionnaire ...... 18 2.5.2 Pilot-testing of the study questionnaire...... 18

2.6 Measurement and Definition of Variables...... 19 2.6.1 Sociodemographic variables ...... 19 2.6.2 The Self-Estimated Functional Inability because of Pain (SEFIP) Questionnaire ...... 20 2.6.3 Eleven-point Numerical Rating Scale (NRS-11)...... 21 2.6.4 Current Treatment and Pain Medication Use...... 21 2.6.5 Injury Status/ Self Reported Injury...... 21 2.6.6 Injury Characteristics...... 21 2.6.7 Injury Reporting...... 22 2.6.8 Dancers’ Attitudes and Perception of Injury ...... 22 2.6.9 Contextual Company Information ...... 22

2.7 Ethics...... 22

2.8 Statistical Analysis ...... 23 2.8.1 Data entry, double data entry, and data cleaning...... 23 2.8.2 Descriptive Statistics...... 23 2.8.3 Prevalence of Dance-related MSK Injury...... 23 2.8.4 Factors associated with MSK-injury in professional dancers...... 24

CHAPTER 3: RESULTS ...... 25

3.1 Response rate...... 25

3.2 Data entry error rate ...... 26

3.3 Sociodemographic characteristics of the study population...... 26

3.4 Self Estimated Functional Inability because of Pain (SEFIP) scores...... 30

3.5 Numeric Rating Scale Scores: Dance related pain over the last week...... 34

3.6 Current treatment...... 37

3.7 Pain Medication Use ...... 42

3.8 Injury Prevalence...... 43

3.9 Factors associated with self-reported dance-related musculoskeletal injuries (SRI) in dancers...... 46 3.9.1 Univariate analysis (crude analysis) ...... 46 3.9.2 Multivariable analysis (logistic regression)...... 50

3.10 Factors associated with SEFIP score of ≥3...... 51 3.10.1 Univariate analysis (crude analysis) ...... 51 3.10.2 Multivariable analysis (logistic regression)...... 56

3.12 Characteristics of Prevalent Injuries ...... 57 3.12.1 Body region injured ...... 57 3.12.2 Injury Duration...... 60 3.12.3 Injury Severity ...... 62 3.12.4 Time Off Work in Past Year...... 62 3.12.5 Recurrent Injuries...... 66

3.13 Relationship between SEFIP scores and SRI ...... 68

3.14 Reporting of Dance-related Injuries ...... 68

3.15 Dancers’ Attitudes and Perceptions of Injury...... 73

3.16 Company Contextual Information ...... 80

CHAPTER 4: DISCUSSION ...... 82

4.1 Principal Findings...... 82

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4.2 Implications of Principal Findings ...... 88

4.3 Strengths and Limitations...... 91

4.4 Future Directions ...... 94

CHAPTER 5: CONCLUSIONS ...... 95

REFERENCES...... 96

APPENDICES …………………………………………………………………..…………….100

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List of Tables Page

Table 1.1 Cross-sectional studies of prevalence and associated factors of musculoskeletal injury and pain in dancers 6 Table 2.1 Number of eligible dancers in each dance company 16 Table 3.1 Response rates 25 Table 3.2 Sociodemographic characteristics of participating dancers: age, sex, marital status, and low-income cut-offs. 28 Table 3.3 Characteristics of participating dancers: Body Mass Index, low body weight, and years dancing. 29 Table 3.4 Country of Origin 30 Table 3.5 Frequency of SEFIP scores ≥ 3 (by company) 32 Table 3.6 Frequency of SEFIP scores ≥ 3 (by style, sex) 33 Table 3.7 Average dance-related pain over last week, Numeric Rating Scale-11 scores 35 Table 3.8 Pain severity using Numeric Rating Scale-11 cut-points. Average dance-related pain over last week 36 Table 3.9 Dancers currently receiving treatment for dance-related pain 38 Table 3.10 Treatment from Healthcare Practitioners (only dancers currently receiving treatment) 39 Table 3.11 Frequency of Treatment from Healthcare Practitioners (only dancers currently receiving treatment) 40 Table 3.12 Site of Current Treatment (only dancers currently receiving treatment) 41 Table 3.13 Pain medication use in last week (all dancers) 42 Table 3.14 Current Injury Status 44 Table 3.15 Point prevalence of Self Reported Injury 45 Table 3.16 Point prevalence of SEFIP ≥3 Injury 45 Table 3.17 Univariate Analysis (ballet dancers only) – Self Reported Injury 47 Table 3.18 Univariate Analysis (modern dancers only) – Self Reported Injury 49 Table 3.19 Final Model for Logistic Regression Analysis. Factors Associated with Self Reported Injury (ballet dancers) 51

Table 3.20 Univariate Analysis (ballet dancers only) – SEFIP score of ≥3 53 Table 3.21 Univariate Analysis (modern dancers only) – SEFIP score of ≥3 55 Table 3.22 Final Model for Logistic Regression Analysis. Factors Associated SEFIP score of ≥3 (ballet dancers) 56 Table 3.23 Body Region Injured (current most problematic injury of injured dancers) by style and sex. 58 Table 3.24 Body Region Injured (current most problematic injury of injured dancers) by company 59 Table 3.25 Duration of Injury (by style and sex) 61 Table 3.26 Duration of Injury (by company) 61 Table 3.27 Injury Severity (by style and sex) 64 Table 3.28 Injury Severity (by company) 64 Table 3.29 Time off work due to current injury in past year (by style and sex) 65 Table 3.30 Time off work due to current injury in past year (by company) 65 Table 3.31 Recurrent Injury (by style and sex) 69 Table 3.32 Recurrent Injury (by company) 67 Table 3.33 Highest Reported SEFIP Score for Injured and Non-injured Dancers 68 Table 3.34 Frequency of non-reported injuries 69 Table 3.35 Reasons for not reporting an injury 70 Table 3.36 To whom are dancers reporting their injuries? 71 Table 3.37 Injuries Reported as Work Injuries 72 Table 3.38 Responses to Attitudinal Questions 75 Table 3.39 Company Contextual Data for the 2007-08 Season 81

List of Appendices Page

Appendix 1 Electronic Database Search Strategies 100 Medline 101 Cinahl 102 Appendix 2 Study Questionnaire 103 Appendix 3 Research Ethics Board Approvals 119 University of Toronto 120 University Health Network 121 Hadassah Hospital (Israel) 122 Datatilsynet (Denmark) 123 Regional Ethics Committee, Lund (Sweden) 128 Appendix 4 Copyright Acknowledgement 130

List of Abbreviations

B: Ballet BAT: Batsheva Dance Company BJHS: Benign joint hypermobility syndrome BMI: Body mass index CAD: Canadian dollar CI: Confidence interval CUL: Cullberg Ballet ENS: Ensemble Batsheva KDC: Kibbutz Contemporary Dance Company KDC2: Kibbutz Contemporary Dance Company 2 M: Modern MD: Medical doctor Med: Median MSK: Musculoskeletal NA: Not available NBC: National Ballet of Canada ND: No data NRS: Numeric rating scale NSAIDs: Non-steroidal anti-inflammatory drugs OR: Odds ratio P: Professional PP: Pre-professional RDB: Royal Danish Ballet RSB: Royal Swedish Ballet SD: Standard deviation SEFIP: Self Estimated Functional Inability because of Pain Questionnaire SRI: Self-reported injury TDT: Toronto Dance Theatre U: University

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WSIB: Workers’ Safety and Insurance Board YS: Young student β: Beta ρ: Rho (Spearman’s rank correlation coefficient)

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Chapter 1: Introduction

1.1 Statement of Problem Dancers are both artists and athletes. Professional dancers train many years, often from a young age, to attain one of the few positions available in professional dance companies. They are subjected to fierce competition from other talented dancers, as well as intense scrutiny from teachers, choreographers, and artistic directors. They must possess innate talent, yet obtain a high level of skill and physical ability. In one study comparing ballet to 61 other sports, it was deemed the second most demanding physical activity on par with bullfighting and second only to football.1

The number of professional modern and ballet dance companies in any one country is small. Therefore, dancers from around the world compete for the few positions available in these companies. This often results in a very internationally diverse work population. Competition does not end once the dancer achieves a professional dance position. Professional ballet dance companies have a ranking system. Most dancers start in the corps de ballet and try to work their way up to soloist and then principal dancer positions. Although modern dance companies may not employ a ranking system, dancers still compete for roles. Injury or pain may impede a dancer’s ability to attain or maintain their position or roles in a company and, at worst, drastically shorten a dancer’s career. The professional dancer’s career is extremely short with most dancers retiring from performance in their mid to late 30s in the United States of America and between the ages of 41-44 in Sweden. 2, 3

A recent systematic review has found the dance medicine literature regarding musculoskeletal injury and pain to be “young and heterogeneous” identifying only 32 published articles as scientifically acceptable. 4 The prevalence of musculoskeletal (MSK) injury in professional dancers ranges from 20-84% while the prevalence of MSK pain is as high as 95%.4 This broad range of prevalence estimates is likely due to different definitions of injury and study methodology. The paucity of high quality studies

1 2 for an occupational group which is at high risk for MSK injury and pain points to the importance of further research in this area. The objective of my thesis is to add to the existing literature on the burden and associated factors of MSK injury and pain in professional ballet and modern dancers by updating a systematic review of the literature and by surveying professional dancers from Canada, Sweden, Denmark, and Israel.

1.2 Literature Review A systematic review of the entire dance medicine literature up to 2004 was performed by Hincapié et al.4 Two themes were identified: (1) MSK injuries and pain; and (2) metabolic and nutritional disorders. With the first author of that study, I updated this review dealing with MSK injuries and pain to 2008 using an identical search strategy (Appendix 1). The primary sources of literature were the electronic databases MEDLINE (2004 to March 2008) and CINAHL (2004 to March 2008). Indexed terms and text words such as dance, dancer, dancing, athletic injuries, occupational injuries, sprains and strains, musculoskeletal diseases, bone density, menstruation disturbances, eating disorders, and others were used to search the databases. 4 Additionally, I examined the reference lists of all relevant studies for additional or unpublished literature.

1.2.1 Screening for relevance Using a best evidence synthesis approach,5, 6we each independently screened all of the citations that were identified through the search strategy and using the previous review’s criteria included: “English language reports; published reports of original research, systematic reviews, conference proceedings, government reports, guidelines, or unpublished “grey literature” manuscripts; studies containing original raw data on at least 20 human research participants, including a control group if present; studies examining the prevalence, incidence, associated factors, risk factors, diagnosis, interventions, economic costs, prognosis, or other aspects of MSK injury and pain, and metabolic and nutritional disorders in dancers; and, studies of dancers in any form of artistic dance such as ballet, modern, tap, theatrical, folk, Flamenco, break-dancing, ballroom dancing, and ice dancing”.4 Using identical exclusion criteria to the previous review, we excluded:

“studies on recreational or exercise forms of dance such as aerobic dancing or social dancing in clubs, parties or raves; studies on the cognitive, behavioral or learning aspects of dance; narrative, editorial or clinical reviews, opinion papers, letters to the editor, and editorials; studies of conditions with questionable clinical relevance or asymptomatic presentation; studies using cadavers or non-human subjects; and, studies reporting findings not specific to dancers (e.g., studies where dancers’ information was combined with other athletes’ information and results could not be evaluated specifically for dancers)”.4

The first author of the previous review and I independently evaluated each citation’s relevancy through a two-level screening process. We obtained and reviewed all papers that were identified as probably relevant, or of unknown relevance in the first level of screening. In the second-level screening, these were then classified as either relevant or irrelevant to the systematic review.4

We maintained the 2 themes from the previous systematic review: (1) MSK injuries and pain; and, (2) metabolic and nutritional disorders. For the purposes of this thesis, I will extract and include information relevant to the first theme, MSK injuries and pain.

1.2.2 Critical review of the literature We critically appraised all relevant studies for scientific merit and clinical relevance by using a priori criteria and computer-based critical review forms.7 Studies were considered scientifically admissible or scientifically inadmissible on the basis of the presence of fatal biases and methodological flaws. We undertook a full discussion of each paper focusing on issues such as design, study population, study conduct, participation and follow up rates, measurement and analysis.4 I have extracted relevant information from the accepted papers, and my update of the review for this thesis focuses on studies relevant to professional ballet and modern dancers.

1.2.3 Characteristics of musculoskeletal injury in dancers The previous review of MSK injuries in dancers reported that most MSK injuries in dancers are soft tissue injuries such as sprains, strains, and tendinopathies primarily

affecting the lower extremities and back.4 Many studies in my updated review did not report exact locations of injuries measured; however, of those that did, lower extremity injuries still predominated followed by hip and low back injury. Three studies accepted in the review update focused on specific injuries including snapping hip syndrome, ankle injuries, and acute hamstring strain.8-10

1.2.4 Prevalence and associated factors of musculoskeletal injury and pain in dancers. Hincapié’s review identified six studies that focused on professional dancers and three studies that included both professional, preprofessional, and/or university level dancers. All of these studies included ballet dancers while only two of the studies included modern dancers.4 In my review update, I identified one study that focused solely on professional ballet dancers,11 one study on professional modern dancers,12 and one study that focused on a mix of professional ballet dancers and elite ballet students.10

Prevalence estimates varied according to time periods and case definitions with estimates ranging from 20% to 95%. Two of the better quality studies reported the 1-year period prevalence of MSK pain in professional Swedish ballet dancers to be approximately 95%, with 90% of those dancers who were followed up 6 years later reporting recurrent pain.13- 15 One study reported the point prevalence of minor recurrent injury in professional ballet and modern dancers to be 89%.16 Another study reported the point prevalence of chronic injury in professional ballet and modern dancers at 48% and the six month period prevalence of injury at 42%.17 The majority of studies reported 12-month or lifetime prevalence increasing the likelihood of recall bias.

Eight of the eleven identified cross-sectional studies reported on factors associated with MSK injury or pain in professional dancers. Factors reported to be positively associated with MSK injury or pain include older age18, female sex 14, male sex 19, years of dance experience18, 20, “overachiever” personality traits18, dance setting17, performance level14, 20, hours of training per day21, menstrual dysfunction21, muscular tension before performing14, work dissatisfaction14, joint hypermobility19, and psychological

5 factors(stress, anxiety, depression, anger, fatigue and confusion)11. The majority of these associations are preliminary in nature. Only one study of professional ballet and modern dancers made use of multivariable statistical methods in assessing the independence of these associated factors.14 In Table 1.1, I outline the cross-sectional studies of professional ballet and modern dancers with reported prevalence estimates and associated factors.

Table 1.1: Cross sectional studies of prevalence and associated factors of musculoskeletal injury and pain in dancers Prevalence Estimates Study;Country Style;Level Study Size Age (y) Outcome Point 6 12 Lifetime Associated Factors (N); month month Response Rate Chmelar et B,M; P,U 39 (18 18-37 Injury 74% ND 23% ND NA al.16; USA Professional (minor (major dancers); injury); injury) 64% 89% P only Hamilton et B; P 29; 64% 22-41 Injury ND ND ND 20-79% Age, years of dance, al.18; USA personality traits Bowling17; UK B,M; P 141; 75% >18 Injury 48% 42% ND 84% Dance setting (chronic) McNeal et al.20; B; 350 (99 <13 Injury ND ND ND 20-80% Years of dance, USA/Canada P,PP,U,YS professional and performance level dancers); 80- ≥13 100% Kadel et al.21; B; P 54; 55% NA Stress ND ND ND 32% Hours of training per Sweden fracture day, menstrual dysfunction Ramel and B; P 64; 84% 17-47 Pain ND ND 69- ND Sex, performance Moritz14; 94% level, muscular Sweden tension before performing, work dissatisfaction Abbreviations: B, ballet; BJHS, benign joint hypermobility syndrome; M, modern; NA, not available; ND, no data; P, professional; PP, preprofessional; U, university; YS, young student.

Table 1.1: Cross sectional studies of prevalence and associated factors of musculoskeletal injury and pain in dancers

Prevalence Estimates Study;Country Style;Level Study Size Age (y) Outcome Point 6 12 Lifetime Associated Factors (N); month month Response Rate Ramel and B; P 128; 87% 17-47 Pain ND ND 61- ND Nonassociated factors: Moritz13 and 51; 60% 95% age, sex, workload Ramel et al.15; Sweden McCormack et B; P,PP 287 (71 NA Injury NA (study focused on hypermobility Sex, joint al.19; England professional and BJHS) hypermobility dancers); NA Adam et al.11; B; P 54; 78% NA Injury NA ND 87% ND Stress, sleep Germany problems, negative mood states Scialom et al.12; M; P 30; 75% NA Injury ND ND ND 47% NA Brazil Winston et B; P,PP 87; 92% >16 Snapping ND ND ND 91% Movements associated al.10: Canada hip with snap: Grand syndrome battement à la seconde (42%), grand plié (25%), développé à la second (22.8%).

Abbreviations: B, ballet; BJHS, benign joint hypermobility syndrome; M, modern; NA, not available; ND, no data; P, professional; PP, preprofessional; U, university; YS, young student.

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1.2.5 Incidence of and risk factors for musculoskeletal injury and pain in dancers In the review of Hincapié et al., eight cohort studies of professional dancers were identified. Only one study focused on professional modern dancers. Five studies focused on professional ballet dancers and two studies examined both professional ballet dancers as well as university or high school level ballet students.4 In my review update, I identified an additional five cohort studies of dancers; however, only one study included professional ballet dancers along with university and high-school level dancers. The remaining four studies included only university or preprofessional dancers.

The cumulative incidence of musculoskeletal injury in professional dancers ranged from 40% to 94%; however, the follow-up periods varied between studies.4, 22Four studies reported incidence densities. One study of professional ballet dancers reported 0.65 injuries per dancer-year.23 A study of ballet dancers in Sweden reported 0.62 injuries per 1000 dance-hours.24 A study of modern dancers in the United States evaluating an injury management program reported incidence per 1000 dance-hours as 0.51, 0.48, 0.57, 0.29, and 0.18 for each respective five years of the study.25 Lastly, a study of ballet dancers in Norway reported 3.2 injuries per dancer for a five-month follow-up period.26

Risk factors positively associated with musculoskeletal injury and pain that were reported in these cohort studies include age24, female sex for overuse injuries and male sex for acute knee and upper limb injuries23, 24, 27, 28, seasonal timing26, prior injury29, fatigue30, frequency/intensity of training30, psychological characteristics associated with eating disorders30, dieting30 and psychosocial coping31. Nonassociated factors included age27, 28, sex25, rank27, 28, stress/tension26, and feeling of influence on working conditions26. The majority of these studies explored crude associations and therefore these associations are preliminary in nature and may not be independently associated with injury. Only two studies made use of multivariable and/or stratified analysis to determine independent associations with injury.25, 31

1.2.6 Definition of Injury In their systematic review of the literature, Hincapié et al found that the definition of an “injured dancer” varied considerably.4 In many studies, no definition was provided, while others

9 restricted their sampling to dancers with compensable injuries by the Worker’s Compensation Board. Some studies restricted their definition to injuries that required attention by a health care professional. Overall, Hincapié et al reported that definitions tended to be vague. This vagueness is illustrated in one study that defined a dance injury as “one that affected the dancer’s dancing in some way”, or as an event resulting in financial outlay by the company.4 My update to this review found that the majority of studies did report on their use of a specific definition of musculoskeletal injury in dancers.8, 11, 12, 31-34 Of those that reported a definition of injury, they were more uniform than the definitions reported in the previous systematic review incorporating either a time-loss or functional component to the definition.

The International Association of Dance Medicine and Science’s Standard Measures Consensus Initiative is in the process of making recommendations on how to measure and define injury.35 Similarly, Bronner et al have proposed a uniform reporting guideline that includes a standardized definition of injury based on existing reporting systems for athletes.36 The International Performing Arts Injury Reporting System instrument uses a definition of injury based on time- loss from dance activity.35 However, Bronner’s proposal calls for a broader definition of injury that encompasses any physical complaint resulting from dance-related activity.36 Dance UK, a British organization for dancers, defines injury as “… a physical problem deriving from stress or other causes to do with performance, rehearsal, training, touring or the circumstances of dance life, which affects your ability to participate fully in normal training, performance or physical activity”.37 To date however, there is no consensus of a definition of injury amongst dance health practitioners and researchers.

While some advancement has been made regarding the definition of injury, we still know little about how dancers perceive and cope with musculoskeletal injury. No study in the systematic review, or my update of the review, has reported on professional dancers’ attitudes and perceptions of injury.4, 22 Knowledge and understanding of injury from the dancers’ perspective will help to inform both researchers and health care practitioners dealing with dance injuries. A recent qualitative study of modern dance students, teachers, community dancers, professional dancers, and former dancers reports that half of the participants defined injury as “something that stopped them from dancing or from moving normally.” The second most common response was “an injury caused by a particular type, quantity, or location of pain”, although the two statements

10 were not always mutually exclusive. A minority of the participants defined injury solely as an acute event accompanied by visual signs such as swelling and bruising.38

1.2.7 Injury Reporting Few studies have addressed the issue of injury reporting in professional dancers. One cross- sectional study reported that between 15-30% of dancers who are injured do not seek medical attention.20 Psychological issues that may cause a dancer to “dance through” or with pain or injury include the fear of losing a role, losing their job, being considered unreliable, or pressure by the company to perform rather than cancel a performance.39 A British study reports that only 32% of professional dancers stopped and rested after an injury occurred, with the majority of dancers continuing to dance as best they could with no rest.17 Of 376 different dance-related injuries treated by a naprapath employed by the Stora Theatre in Gothenburg over a three year period, only 20 injuries were officially reported. These non-reported injuries included injuries as varied as non-specific neck pain to stress fractures.13 In one Swedish study more than half of the dancers reported that they had worked on several occasions when they felt they should not have due to injuries, fatigue, or illness.40 For many reasons, dancers may be dancing through or past what health care providers consider an injury. The issue of non-reporting of injuries is very important, as it could bias all measures of incidence or prevalence of musculoskeletal injuries in dancers. More importantly, this could lead to long-term health consequences for injured dancers. Hincapié et al recommended in their systematic review that further research is needed to determine how commonly musculoskeletal injury is not being reported by dancers to their respective dance companies and the reasons dancers are not reporting their injuries.4

1.2.8 Assessment Tools for Musculoskeletal Injury and Pain in Dancers Hincapié et al identified one study of a diagnostic and assessment tool for musculoskeletal pain and functional limitation.4, 40 The Self Estimated Functional Inability because of Pain (SEFIP) questionnaire is a tool developed specifically for dancers based on the Nordic Musculoskeletal Questionnaire. The SEFIP is a validated questionnaire created specifically for dancers, and has good agreement with actual pain and dysfunction found on physical examination.40 The SEFIP is described further in section 2.6.2.

1.3 Environmental Scan of Healthcare and Social Programs I have performed an environmental scan of healthcare and social programs in nine professional dance companies in Canada, Israel, Denmark, and Sweden by interviewing the artistic and administrative staff of each company. An environmental scan provides information of internal and external conditions about an organization.41 Each of these countries has a publicly funded national healthcare system; however, coverage of care for dance-related injuries varies in each country as well as in each company. Physiotherapy and other paramedical services are not covered by the public health system in Ontario. The National Ballet of Canada and the Toronto Dance Theatre both supply extended health care coverage to their dancers which covers these services up to a certain amount. Additionally, the National Ballet of Canada has on-site physiotherapy available at no cost to the dancers and a medical doctor is available on-site one day each week. Dancers in the Toronto Dance Theatre must receive physiotherapy or other paramedical services off-site, and then seek reimbursement from their extended health care insurance.

Israel’s health care system does cover physiotherapy and other paramedical services. The Batsheva Dance Company and Ensemble (Israel) does not have on-site healthcare, but has a physiotherapist associated with the company. Visits to this specific physiotherapist are covered by the company without restriction of number of visits. Additionally, the company provides an option for each dancer to seek physiotherapy or other paramedical services such as chiropractic care, massage therapy, or acupuncture from a roster of practitioners up to a maximum of 23 treatments per season. The Kibbutz Contemporary Dance Company (Israel) and its junior company provide on-site physiotherapy, massage and acupuncture three times a week at no cost to the dancer.

The Royal Swedish Ballet provides on-site physiotherapy and naprapathic care at no cost to the dancers. A nurse is available on-site everyday and an orthopedic and ear, nose, and throat specialist are available on-site one day a week. Dancers may also seek off-site paramedical treatment up to a limit of 900 Swedish Kroner ($130 CAD) per year. The Cullberg Ballet (Sweden) does not have on-site care, but pays for all care sought externally for its dancers. Non- injured dancers are limited to one treatment per week.

Denmark provides partial coverage for physiotherapy and paramedical services; however, the Royal Danish Ballet has the most extensive on-site healthcare available for its dancers of all the companies I interviewed. Services provided on-site to the dancers at no cost include: physiotherapy, massage, sports psychology, medical doctor, orthopedic specialist, dietician, and special “sick classes” for injured dancers. The company will also reimburse 50% of the cost for off-site treatment if this is approved in advance.

Workers’ compensation coverage varies by country and company as well. The Toronto Dance Theatre dancers are covered by the provincial Workplace Safety and Insurance Board (WSIB); however, the National Ballet of Canada dancers are not covered by the WSIB. Dancers in both companies have long term disability plans provided by the company. Israel has a National Insurance (Bituach Leumi) which is accessed if the dancer is disabled due to a work related injury. The Batsheva Dance Company and Kibbutz Contemporary Dance Company additionally provide their dancers with optional private disability insurance. Scandinavian countries are well known for their social support programs for injured workers. Swedish dancers are covered by the national workers’ compensation insurance. It should be noted that non-Swedes working in Sweden are entitled to the same benefits. The company pays an injured dancer’s salary for two weeks after which it is paid by the national insurance. Sweden is moving towards a new system with additional limitations. Dancers’ work injuries in Denmark are also covered by a national insurance. Similar to Sweden, injuries are reported after two weeks to the national insurance.

Employment security also varies drastically between companies and countries. The Scandinavian companies again have the strongest employment security. Once a dancer is employed by a Swedish or Danish dance company for three years, they obtain permanent lifetime employment. Swedish dancers can then take a leave of absence for up to three years if desired (for example to work elsewhere) and have guaranteed employment upon return. Swedish and Danish dancers may retire at the age of 40 with pension. In the Israeli companies, employment is on a season by season basis, however dancers are employed year round. In the Canadian companies, dancers are hired seasonally and most are “laid off” in the summer months. No pensions exist for Israeli or Canadian dancers.

1.4 Summary and Rationale Informed by the systematic review of the dance medicine literature and my update to this systematic review, it is apparent that information is still lacking in regards to professional dancers and musculoskeletal injury and pain. Multivariable analysis has rarely been used to determine the independence of factors associated with injury in professional dancers. Additionally, very few studies have included or focused on professional modern dancers, who are also at risk for musculoskeletal injury that might have long-term consequences for their future health.

A need for information regarding professional dancers’ attitudes and perceptions of injury exists. Dance health practitioners and researchers have yet to come to a consensus on the definition of a dance injury. Understanding injury from the dancers’ perspective could inform future research to better capture all potentially injured dancers and provide a clearer and more comprehensive picture of dance injuries overall.

Lastly, it is apparent that for many reasons dancers may be wary to report an injury. The understanding of reasons why dancers may not report an injury can help the development of future research methodology to provide better prevalence and incidence estimates. The reporting of injury also may vary between companies and countries with varying levels of social and medical support for dancers.

With these issues in mind, I undertook an international cross-sectional survey based study of professional ballet and modern dancers in Canada, Denmark, Israel, and Sweden.

1.5 Primary Objectives and Research Questions The primary objective of my research is to determine the point prevalence of dance-related musculoskeletal injury in professional ballet and modern dancers and the factors associated with these dance-related injuries.

The secondary objectives of my research are: 1. To report the characteristics and patterns of these dance-related injuries. 2. To explore professional dancers’ attitudes and perceptions of injury.

3. To assess if professional dancers are not reporting injuries and why they might not report their injuries.

CHAPTER 2: Methods and Materials

2.1 Study design This study is a cross-sectional survey of professional ballet and modern dancers in Canada, Sweden, Denmark and Israel.

2.2 Source population/Setting Participants were recruited from three professional ballet and six modern dance companies in Canada, Sweden, Denmark and Israel. Due to the small number of professional dance companies in each country, I aimed to recruit companies in multiple countries in order to increase sample size. Working with research and dance contacts in these countries, I approached the directors of various dance companies with an aim to recruit the largest modern and ballet companies in each country as part of this convenience sample. Participating ballet companies included the National Ballet of Canada, the Royal Swedish Ballet and the Royal Danish Ballet. Participating modern dance companies included the Toronto Dance Theatre (Canada), the Cullberg Ballet (Sweden), the Batsheva Dance Company (Israel), the Batsheva Ensemble (Israel), the Kibbutz Contemporary Dance Company (Israel), and the Kibbutz Contemporary Dance Company 2 (Israel). Table 2.1 outlines the total number of dancers eligible for participation in each company.

The participating companies were chosen as they represent the highest standard of ballet or modern dance in that country and are recognized as premier companies in each country and internationally. All three ballet companies are considered the “national” ballet company of the country and have a full range of classical ballets in their repertoire. In addition, the National Ballet of Canada and the Royal Danish Ballet have incorporated neoclassical and contemporary works into their repertoire. The modern dance companies each have a “house” choreographer and primarily dance works by that choreographer as well as additional repertoire by guest choreographers.

All the dance companies have very similar workday schedules. This begins with a company class (1 to 1¼ hours) to prepare for the workday followed by 6 hours of rehearsal on a non- performance workday. All three ballet companies begin the day with a ballet class while the 15 16 modern companies begin with either a modern or ballet class. Work days on which performances take place vary slightly with a later start for evening performances and shorter rehearsal times.

Table 2.1 : Number of Eligible Dancers in Each Dance Company Number of Eligible Dancers Ballet Companies: National Ballet of Canada 69 Royal Swedish Ballet 67 Royal Danish Ballet 83

Modern Dance Companies: Toronto Dance Theatre 16 Cullberg Ballet 20 Batsheva Dance Company 20 Batsheva Ensemble 15 Kibbutz Contemporary Dance Company 17 Kibbutz Contemporary Dance Company 2 12

Total Number Eligible Dancers: 319 Eligible = employed by dance company at time of study, age ≥18, not on leave of absence to dance in another company (only Scandinavian companies), not character dancer. See section 2.3 for further detail.

2.3 Inclusion/Exclusion Criteria Any dancer employed by the participating dance companies at the time of data collection was eligible to participate with the exclusion of dancers younger than eighteen years of age due to issues of consent. Dancers who had taken an extended leave of absence to dance in another company and were not presently dancing with their company were also excluded. This would only be an issue in the Scandinavian companies where dancers are able to take a three year leave of absence in order to dance with another company while maintaining their employment status with the original dance company. The company management was instructed not to forward a questionnaire to these dancers. Character dancers were also excluded as their work hours and current dance exposure is very different than the other dancers. Character dancers often are older dancers in ballet companies and have roles with more mime and gesture type of movements, rather than the strenuous dance of the other company members.

2.4 Recruitment/Survey Methodology A date for survey distribution was arranged with the company management. A common time in the season for data collection was not possible to arrange due to the complex touring and performing schedules of all companies involved. Companies were instead asked to arrange a time for the survey distribution which would occur during a period in which performances were taking place and that did not occur immediately after vacations or holidays. This was done in order to make the dance exposure as uniform as possible with various companies and repertoires. Additionally, company managers and directors had noted that performance periods seemed to be the periods in which more dancers were injured. To encourage participation, a 45-minute time for survey completion was scheduled during the regular workday in which all dancers would be present. This eased the burden on the dancers as it took place either after company class or after a rehearsal which involved all the dancers.

A brief explanation of the purpose of the study as well as the informed consent process took place prior to the distribution of the survey. Neither company management nor artistic personnel were present during the survey distribution, so dancers would not feel pressured to participate. The company management was not aware of which dancers did or did not participate in the study. One investigator who was familiar with the study and spoke the native language of the country was present to clarify any questions. All dancers received a study package that included

18 a study questionnaire, an introductory letter and a pre-stamped addressed envelope. Participation was voluntary and the dancers were instructed not to write any identifying information on the questionnaire. Dancers were given the option to complete the survey during the time provided or at their own convenience. Upon completion, they were asked to seal their completed questionnaire in the provided envelope and return it to a locked drop box on site or by post. All dancers not present on the day of the survey were forwarded a study package by the company to ensure that dancers who were off work due to illness or injury would have the opportunity to participate. Bulletin board and/or email reminders were utilized to remind dancers who had not yet responded to return the survey to the drop box or by post.

2.5 Description and Pilot-Testing of the Questionnaire

2.5.1 Description of the study questionnaire The study questionnaire (Appendix 2) consists of two parts. The first part is the Self Estimated Functional Inability because of Pain (SEFIP) questionnaire. It is the only published tool developed and validated specifically to measure musculoskeletal pain and function in dancers.40 The second part consists of five sections (A-E). Section A consists of 7 items dealing with current dance-related pain, injury, and treatment and includes Numeric Rating Scales (NRS). Section B contains 7 items dealing with the effect and burden of dance-related pain over the past six months. Section C contains 9 attitudinal questions regarding dancers’ perception of musculoskeletal injury and one question regarding their current injury status. Section D contains 11 items specific to the dancers’ current injury. Lastly, section E consists of 16 demographic questions.

2.5.2 Pilot-testing of the study questionnaire The development and pilot-testing of the study questionnaire was performed prior to my enrollment at the University of Toronto and therefore is not an official component of my thesis.42 However, a brief description of the process is essential. The study questionnaire was developed and pilot-tested using standard questionnaire development methodology.43 An environmental scan and literature review was performed. The pilot questionnaire was evaluated by two epidemiologists with expertise in survey development for face validity. An expert in dancers’ health evaluated the questionnaire for face and content validity and to ensure the questionnaire’s applicability in an international setting. The survey was also evaluated by one dance company

19 manager and one rehearsal director in Israel to ensure the information would be useful and relevant to primary stakeholders. The questionnaire was then pilot-tested on nine dancers from the National Ballet of Canada. Twenty-two percent of the items needed revision or clarification based on incorrect answers, absent answers, or written feedback from the dancers. All ambiguous, problematic or double-barreled questions were identified and revised by consensus amongst the thesis committee members. Discussion with the participating dance companies revealed that the working language in each company was English. Therefore, I decided to administer the questionnaire only in English. The revised questionnaires were sent to co- investigators in Sweden, Denmark and Israel. These investigators were requested to provide further input and identify any questions or words that may be confusing. Therefore cross-cultural face validation was achieved by addressing these issues. A specific questionnaire was developed for each distinct country. All questions were the same, however country specific units (i.e. currency) and translations in parentheses were provided for words which were identified as potentially confusing by the coinvestigator for that country.42

2.6 Measurement and Definition of Variables

2.6.1 Sociodemographic variables Sociodemographic variables from the study questionnaire used to describe the study population and to estimate their association with dance injury include: age, sex, height, weight, and before- tax yearly or monthly income (Appendix 2 Section E). Body mass index (BMI) was calculated from the height and weight variables using the formula: BMI = kg/m2. Low BMI levels were defined as <18.5 based on Canadian Guidelines for Body Weight Classification in Adults.44 Low-income cut-offs were obtained or calculated from the official statistical authority of each country. Low income cut-off points defined for each country are: Canada, <20,778 Canadian Dollars/year45; Sweden, <140,400 Swedish Krona/year (20,140 CAD)46; Denmark, <100,000 Danish Krone/year (20,310 CAD)47; Israel, <3,710 Israeli New Shekel/month (1,025 CAD)48.

Dance specific characteristics are: number of years in present dance company, number of years dancing professionally, number of years dancing total, and rank in the company (Appendix 2 Section E). Number of years dancing professionally was defined as: the dancer received payment for work as a dancer either in a dance company or freelance. Number of years dancing total was defined as: dance training at least three times per week plus professional experience.

2.6.2 The Self-Estimated Functional Inability because of Pain (SEFIP) Questionnaire The SEFIP is the only validated diagnostic and assessment tool for dancers identified in the dance medicine literature.4, 40 The SEFIP is an English language questionnaire based on the Nordic Musculoskeletal Questionnaire and measures the intensity of current pain as well as ability to dance on a 5-point scale for 14 distinct body regions40. These points are: 0 = “very well”; 1 = “some pain but not much problem”; 2 = “pretty much pain but I can handle it”; 3 = “much pain, must avoid some movements”; 4 = “cannot work in the production because of pain”. The SEFIP was validated by Ramel et al using a test-battery for pain and muscular dysfunction designed for dancers.40 Overall good agreement was demonstrated between the SEFIP and the test-battery. The mean agreement was 88% with a range of 75% (hips) to 96% (neck) and a mean kappa value of 0.69. The sensitivity and the specificity were calculated for each body region. The mean sensitivity and specificity of the SEFIP over the body regions is 72% and 86% respectively. This rises to 86% and 88% respectively if shins, elbows and wrists were excluded. The authors concluded that any dancer with a score of 2 or greater should be referred for physical examination by a healthcare practitioner. Of the 14 body regions with an intensity of 3 or more in Ramel’s work, 13 were found to have positive findings in the test battery. Ramel et al additionally report that of the 31 painful areas without positive findings in the test battery, only one of these had a SEFIP score of 3, while seven had a SEFIP score of 2, and 23 had a SEFIP score of 1.40

The SEFIP is scored on a scale of 0 – 4 for each body region (Appendix 2, Page 106). The authors also suggest that a sum score may be reported to look at a company’s overall musculoskeletal pain and function burden at different time periods. One would add all the body regions to obtain a score out of 64 points for each dancer using a maximum score of 4 for 16 body regions.40 However, as I was not repeating the test for each company, I have chosen not to report a sum score, but to focus on the individual scores for each body part. This is essential as a dancer may have a very high score in one body region, but an overall low sum score. A score of 3 represents significant pain accompanied by functional modification of movement. I have therefore chosen to report SEFIP scores of 3 or more in order to reflect the percentage of dancers with a functional component associated with their dance-related pain. Additionally, I use a SEFIP score of 3 or more as an additional or alternative outcome measure of injury prevalence in addition to self-reported injury.

2.6.3 Eleven-point Numerical Rating Scale (NRS-11) The Eleven-point Numerical Rating Scale (NRS-11) was used to measure average dance-related pain over the last week (Appendix 2, Section A). This scale is valid and reliable.49, 50 Cut-points of four and seven were used to differentiate between “mild”, “moderate”, and “severe” pain.50

2.6.4 Current Treatment and Pain Medication Use Dancers were asked whether they are currently receiving treatment, the type of practitioner they are receiving care from, and if their treatment was on or off-site. Dancers were additionally asked to report on their use of prescription and non-prescription pain medication in the past week for dance-related pain (Appendix 2, Section A).

2.6.5 Injury Status/ Self Reported Injury I have used Bronner’s definition of injury, “any physical complaint sustained by a dancer resulting from company performance, rehearsal, or technique class, irrespective of the need for medical attention or time-loss from dance activities” as a working definition of injury for the purposes of this study.36 The pilot study indicated that dancers had difficulty reporting themselves as solely either “injured” or “not injured”.42 I have therefore evaluated dancers’ perception of their injury status by asking them to choose from the following variables: “injured”, “recovering from an injury”, “suffering from a persistent injury”, or “not injured” (Appendix 2, Section C). As I was also collecting information regarding dancers’ attitudes and perceptions of injury, I purposefully did not define injury for them. This qualitative information will be analyzed in a future paper and asks about definitions of injury in open-ended questions. For the purposes of this study, any dancer choosing “injured”, “recovering from an injury”, or “suffering from a persistent injury” will be considered “injured” and reported as self reported injury (SRI).

2.6.6 Injury Characteristics Variables chosen as injury characteristics include: dance or non-dance related injury, duration of injury, severity of injury, time-off due to injury, previous injury occurrence, and time of previous injury occurrence (Appendix 2, Section D). These injury characteristics have been measured for self-reported injury.

2.6.7 Injury Reporting Dancers with self-reported injury were asked if they have reported their injury and if so, to whom they have reported their injury. Those dancers that did not report their injury were asked to indicate why they did not report their injury. They were given the choice of specific reasons why they had not reported their injury (Appendix 2, Section D).

2.6.8 Dancers’ Attitudes and Perception of Injury Dancers were asked to respond to nine attitudinal questions regarding injury. They were asked if they considered themselves injured in relation to pain, functional changes, time-loss from work and other possibilities (Appendix 2, Section C). After each statement, options available are: strongly agree, agree, mildly agree, mildly disagree, disagree, and strongly disagree.

2.6.9 Contextual Company Information This information was collected in the environmental scan in meetings with the artistic and administrative staff of each participating company. The information that was collected common to each company includes: number of dancers in the company, number of performances per year, number of productions per year, if daily company class is required, if onsite treatment is available, number of weeks of vacation per year, if the dancers are unionized, if the company provides “sick classes” for injured dancers, and if the company dances on a raked stage.

2.7 Ethics Ethical approval for the study protocol was obtained from the research ethics boards of: University Health Network (Toronto, Canada), the University of Toronto (Toronto, Canada), Lund University (Lund, Sweden), University of Southern Denmark (Odense, Sweden), and Hadassah Hospital (Jerusalem, Israel). Ethics board approvals are located in Appendix 3.

2.8 Statistical Analysis

2.8.1 Data entry, double data entry, and data cleaning Data was entered into SPSS 15.0 for Windows. Data cleaning was performed by manual inspection and frequency analysis of variables. Outlying, unusual, or missing entries were checked with the original questionnaires and corrected if necessary. Thirteen percent double data entry was performed and an error rate was calculated using Statistical Analysis Software (SAS) proc compare function.

2.8.2 Descriptive Statistics Means with standard deviations and medians are used to describe the distribution of continuous variables. I have additionally reported minimum and maximum scores for the NRS-11 to describe the range of dance-related pain over the past week. Frequency and proportions in form of percentages are reported for categorical data.

2.8.3 Prevalence of Dance-related MSK Injury I have chosen to use two distinct outcomes to estimate the prevalence of dance-related MSK injury: Outcome 1: Self Reported Injury (SRI). To be reported as injured, the dancer had to choose that they were injured, recovering from an injury, or suffering from a persistent injury.

Outcome 2: SEFIP score ≥3. In this analysis the dancer was defined as injured if they had a SEFIP score ≥3 for any body region. This definition has a functional component (modifying movement in order to dance).

To estimate self-reported injury prevalence, all non-dance related injuries were removed. The options “injured”, “recovering from an injury”, and “suffering from a persistent injury” were collapsed to form the numerator. The denominator for the self reported injury prevalence estimate was the total number of dancers who responded to that specific question. This is reported by dance company and style. I have reported 95% confidence intervals for the self- reported injury point prevalence estimates.

To estimate SEFIP ≥3 injury prevalence, the number of distinct dancers with at least one body region score of three or more was used for the numerator. The denominator was the total number of dancers who responded to the SEFIP. This is reported by dance company and style. I have reported 95% confidence intervals for the SEFIP ≥3 injury prevalence estimates.

2.8.4 Factors associated with MSK-injury in professional dancers Logistic regression using Statistical Analysis Software 9.1 was performed to determine which variables are associated with injury. Logistic regression is an appropriate statistical test when the dependent variable is dichotomous as it is in this situation: “injured” or “not injured”.51, 52 Two separate analyses were performed using the two different outcomes for “injury”. These are self- reported injury and SEFIP score ≥3. The choice of variables to include in the analysis was informed by the literature review. The independent variables analyzed are: sex, low body weight, style of dance, low income, company, country, number of years dancing professionally, number of years dancing total, age, number of years in present company, and rank (ballet only). The continuous variables “number of years dancing total”, “number of years dancing professionally”, “number of years dancing in the present company”, and “age” were highly skewed, therefore quartiles were derived.

A preliminary univariate analysis was performed separately for ballet dancers and modern dancers. Any variables with a p-value of less than 0.25 were then included in the multivariable models. Backwards stepwise regression was then performed on these models and items with a p- value greater than 0.10 were removed from the model. The strength of the association of each variable with self reported injury and SEFIP score ≥3 is reported in the form of odds ratios with 95% confidence intervals.

CHAPTER 3: Results

3.1 Response rate

Response rates by company are presented in Table 3.1. The response rates for ballet companies were very similar with an overall response rate of 81%. The response rates for modern dance companies ranged between 65 to 100% with an overall response rate of 82%. Two companies had response rates lower than 80 percent. The reason for the lower response rates in the Kibbutz Contemporary Dance Company and the Kibbutz Contemporary Dance Company 2 is most likely due to difficult working conditions on the day the survey was scheduled. Survey distribution took place after a technical run in a new studio without a proper ventilation system on a day of extreme heat.

Table 3.1: Response rates Company # of participants # of dancers Response Rate (%) Ballet Companies: National Ballet of Canada 55 69 80 Royal Swedish Ballet 55 67 82 Royal Danish Ballet 68 83 82 Total Ballet Dancers 178 219 81

Modern Companies: Toronto Dance Theatre 14 16 88 Cullberg Ballet 16 20 80 Batsheva Dance Company 18 20 90 Ensemble Batsheva 15 15 100 Kibbutz Contemporary Dance Company 11 17 65 Kibbutz Contemporary Dance Company 2 8 12 67 Total Modern Dancers 82 100 82

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3.2 Data entry error rate The total number of discreet variables entered into the statistical software was 156 for 266 study participants. A 13% double data entry was performed and 19 entry errors were identified. This resulted in an error rate of 0.3%. These errors were corrected.

3.3 Sociodemographic characteristics of the study population The sociodemographic characteristics of age, sex, marital status, and income are reported in Table 3.2. Dancers in the Scandinavian companies (Royal Swedish Ballet, Royal Danish Ballet, and Cullberg Ballet) are slightly older. The two junior companies (Ensemble Batsheva and Kibbutz Contemporary Dance Company) are younger due to the nature of these companies. There were more female participants than male participants in all three ballet companies. Overall, 58% of ballet dancers were female. Male to female ratio of participants varied in the modern dance companies and led to an overall equal percentage of male and female participants when combined. Higher percentages of reported income below the low income cut-off were reported in both Canadian companies (National Ballet of Canada and Toronto Dance Theatre) as well as the Kibbutz Contemporary Dance Company 2.

The characteristics of body mass index and low body weight, as well as exposure to dance (number of years dancing) are presented in Table 3.3. Mean body mass index is lowest in the female National Ballet of Canada dancers; however, all three ballet companies had percentages of females with low body weight approaching or greater than 50%. Scandinavian dancers (ballet and modern) had the longest mean years dancing professionally and years dancing total.

Position or rank in the company was not reported in table format due to the differences in ranking between companies. All ballet companies use a hierarchal ranking system consisting of apprentice, corps de ballet, soloist and principal dancers. The Royal Swedish Ballet however, does not have any apprentice dancers. Of the National Ballet of Canada participants, 7(12.7%) were apprentices, 25(45.5%) were in the corps de ballet, and 23(41.8%) were soloists or principal dancers. Of the Royal Swedish Ballet participants, 33(61.1%) were in the corps de ballet and 21(38.9%) were soloist or principal dancers. Of the Royal Danish Ballet participants, 4(5.9%) were apprentices, 39(57.4%) were in the corps de ballet, and 25(36.8%) were soloist or principal dancers. The Cullberg Ballet, the Batsheva Dance Company, and the Kibbutz

Contemporary Dance Company do not have any ranking system. The Toronto Dance Theatre has full and junior company members as well as apprentices. Of the Toronto Dance Theatre participants, 10(71.4%) were full company members, 2(14.3%) were junior company members and 2(14.3%) were apprentices. The Batsheva Ensemble and the Kibbutz Contemporary Dance Company 2 do not have a ranking system, but do have apprentices in the company. Of the Batsheva Ensemble dancers, 1(6.7%) participant was an apprentice. Of the Kibbutz Contemporary Dance Company 2 dancers, 1(12.5%) participant was an apprentice.

The percentage of dancers whose origin is from the country where the dance company is located is reported in Table 3.4. The Cullberg Ballet had the lowest percentage of dancers from the country where the company is located (31.3%) while the Kibbutz Contemporary Dance Company 2 had the highest frequency (100.0%). In order not to identify specific dancers in each company, the country of origin of all dancers is not broken down by company. Besides Canada, Sweden, Denmark and Israel, dancers from the following countries participated in the study: Armenia, Australia, Austria, Belarus, Belgium, Brazil, Bulgaria, China, England, Finland, France, Germany, Hungary, Iceland, Italy, Japan, Lithuania, Mexico, New Zealand, Norway, Philippines, Poland, Russia, Scotland, Serbia, South Africa, Spain, Switzerland, USA, and Zambia.

Table 3.2: Sociodemographic characteristics of participating dancers: age, sex, marital status, and low-income cut-offs.

Ballet Companies Modern Dance Companies

NBC RSB RDB TDT CUL BAT ENS KDC KDC2 Demographic n=55 n=55 n=68 n=14 n=16 n=18 n=15 n=11 n=8

Age in years mean(SD),med 26(5.4),25 30(6.3),30 27(6.1),26 26(4.8),26 30(4.7),30 27(3.4),27 22(2.1),23 25(4.2),25 21(0.8),21 Sex: n(%) Female 29(52.7) 35(64.8) 40(58.8) 6(42.9) 8(50.0) 9(50.0) 7(46.7) 8(72.7) 3(37.5)

Marital status: n(%) Never 31(56.4) 22(41.5) 48(77.4) 13(92.9) 12(75.0) 11(61.1) 14(93.3) 11(100) 8(100) married Married 12(21.8) 14(26.4) 10(16.1) 0 2(12.5) 1(5.6) 1(6.7) 0 0 Common 6(10.9) 16(30.2) 3(4.8) 1(7.1) 2(12.5) 5(27.8) 0 0 0 law Divorced 5(9.1) 1(1.9) 1(1.5) 0 0 1(5.6) 0 0 0 Widowed 1(1.8) 0 0 0 0 0 0 0 0

Income below low income 8(14.5) 2(4.0) 1(1.5) 7(50.0) 0 0 1(6.7) 0 8(100.0) cut-off*: n(%)

Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; KDC, Kibbutz Contemporary Dance Company; KDC2, Kibbutz Contemporary Dance Company 2; SD, Standard deviation; Med, Median;BMI, Body Mass Index. *Low income cut-offs: Canada, <20,778 Canadian Dollars/year; Sweden, <140,400 Swedish Krona/year; Denmark, <100,000 Danish Krone/year; Israel, <3,710 Israeli New Shekel/month.

Table 3.3: Characteristics of participating dancers: Body Mass Index, low body weight, and years dancing.

Ballet Companies Modern Dance Companies

NBC RSB RDB TDT CUL BAT ENS KDC KDC2 n=55 n=55 n=68 n=14 n=16 n=18 n=15 n=11 n=8 BMI: males mean(SD), 22.2(1.2), 22.5(1.6), 22.2(1.3), 22.2(1.1), 22.4(1.7), 22.2(2.2), 20.5(2.0), 20.6(1.0), 22.2(2.5), med 22.4 22.5 21.8 22.2 22.0 21.8 20.6 21.1 20.9 BMI: females mean(SD), 18.2(0.9), 18.7(1.1), 18.5(0.9), 21.3(2.0), 20.7(1.4), 20.4(1.3), 20.1(1.9), 19.7(0.9), 20.2(0.6), med 18.1 18.6 18.4 21.2 20.8 20.1 19.7 19.4 20.3

Low body weight males*: 0 0 0 0 0 0 1(12.5) 0 0 n(% of males)

Low body weight females*: n(% 21(72.4) 17(48.6) 19(47.5) 0 0 0 1(14.3) 1(12.5) 0 of females) Exposure: mean(SD),med

Years in 6.7(5.4),5.0 9.2(7.0),7.5 8.8(6.0),7.0 4.8(3.4).3.5 4.6(5.2),2.5 7.0(2.3).7.0 1.9(0.9),2.0 4.2(3.5),3.0 1.3(0.5),1.0 company

Years dancing 8.1(5.8),7.0 12.4(6.7), 9.7(6.4),8.0 5.3(4.0).4.0 11.2(6.1), 8.6(2.8),9.0 3.2(1.7),3.0 5.7(3.1),5.0 2.1(1.5),1.5 professionally 13.0 9.5

Years dancing 16.0(5.7), 20.7(6.8), 17.3(7.3), 13.4(6.4), 19.0(6.1), 15.7(5.2), 9.5(5.0),8.0 15.2(6.1), 7.6(2.9),7.5 total 15.0 20.5 16.0 12.0 18.5 15.0 15.0 Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; KDC, Kibbutz Contemporary Dance Company; KDC2, Kibbutz Contemporary Dance Company 2; SD, Standard deviation; BMI, Body Mass Index. Low body weight defined as BMI <18.5.

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Table 3.4 Country of Origin Company Name (Country) Dancers Originating from Country of Dance Company n(%) National Ballet of Canada (Canada) 30(54.5)

Royal Swedish Ballet (Sweden) 27(50.0)

Royal Danish Ballet (Denmark) 37(54.4)

Toronto Dance Theatre (Canada) 11(78.6)

Cullberg Ballet (Sweden) 5(31.3)

Batsheva Dance Company (Israel) 12(66.7)

Ensemble Batsheva (Israel) 10(66.7)

Kibbutz Contemporary Dance 8(72.7) Company (Israel) Kibbutz Contemporary Dance 8(100.0) Company 2 (Israel)

3.4 Self Estimated Functional Inability because of Pain (SEFIP) scores Dancers with SEFIP scores ≥3 are reported in Table 3.5. I have chosen to report percentages of scores of 3 or greater, as a score of 3 denotes some degree of functional impairment (“Much pain, must avoid some movements”). Thus, the SEFIP scores can provide a snapshot of the companies’ musculoskeletal health regarding both pain and function for each body region.

Ballet companies’ SEFIP scores followed similar patterns (Table 3.5). When companies were combined, ballet dancers reported highest percentage of SEFIP scores ≥3 for ankles and feet followed by low back, hips, and knees (Table 3.6). This pattern was similar for both males and females. Slight differences did exist between ballet companies for body areas outside of these four most frequent reported problematic regions. The National Ballet of Canada had a higher frequency of SEFIP scores ≥3 for the calf region (5.5%)

compared to the Royal Swedish Ballet (1.8%) and the Royal Danish Ballet (0). The National Ballet of Canada had no reported SEFIP scores ≥3 for the mid-back region compared to the Royal Swedish Ballet (3.6%) and the Royal Danish Ballet (6.9%). The posterior thigh region differed between males (1.4%) and females (4.9%) with the majority of these scores occurring in the Royal Swedish Ballet with 9.1% of the dancers having SEFIP scores ≥3 for the posterior thigh region. Overall, the frequency of SEFIP scores ≥3 for the upper limb in ballet dancers was very low. Only the dancers in the RDB reported any SEFIP scores ≥3 for the shoulder (2.7%) and the wrist hand regions (1.4%). No ballet dancers reported SEFIP scores ≥3 for the elbows or the anterior thigh regions.

In contrast to ballet dancers, modern dancers’ body region with the highest percentage of SEFIP scores ≥3 varied between modern dance companies (Table 3.5). The shoulder region was highest for the Toronto Dance Theatre dancers (21.4%). The low back region was highest for the Cullberg Ballet (25.1%), Kibbutz Contemporary Dance Company (27.3%) and Kibbutz Contemporary Dance Company 2(37.5%) dancers. Toes were equally as problematic for the Kibbutz Contemporary Dance Company 2 dancers. The neck was the most problematic region for the Batsheva Dance Company dancers (22.3%). The Ensemble Batsheva dancers had equal problems with low back, hips, shoulders, wrist/hand, and ankles/feet (6.7%). No male modern dancers reported SEFIP scores ≥3 for the neck compared to 12.2% of females (Table 3.6). Male modern dancers did report SEFIP scores ≥3 for the wrist/hand (4.9%) and the shin (4.9%) regions while no females reported SEFIP scores ≥3 in these regions. No modern dancers reported SEFIP scores ≥3 for the anterior thigh or calf regions.

Table 3.5: Frequency of SEFIP scores ≥ 3 (by company) NBC RSB RDB TDT CUL BAT ENS KDC KDC2 Location n=55 n=55 n=68 n=14 n=16 n=18 n=15 n=11 n=8 n(%) n(%) n(%) n(%) n(%) n(%) n(%) n(%) n(%) Neck 1(1.8) 1(1.8) 0 1(7.1) 0 4(22.3) 0 0 0

Mid-Back 0 2(3.6) 5(6.9) 1(7.1) 1(6.3) 0 0 1(9.1) 1(12.5)

Elbows 0 0 0 1(7.1) 0 0 0 0 0

Lower Back 3(5.5) 5(9.1) 8(11.0) 1(7.1) 4(25.1) 2(11.2) 1(6.7) 3(27.3) 3(37.5)

Hips 5(9.1) 5(9.1) 3(4.4) 0 1(6.3) 3(16.7) 1(6.7) 1(9.1) 0

Posterior Thighs 0 5(9.1) 1(1.4) 0 0 0 0 1(9.1) 0

Shoulders 0 0 2(2.7) 3(21.4) 0 1(5.6) 1(6.7) 0 0

Wrists/hands 0 0 1(1.4) 0 0 1(5.6) 1(6.7) 0 0

Anterior Thighs 0 0 0 0 0 0 0 0 0

Knees 3(5.5) 6(10.9) 4(5.9) 0 2(12.5) 0 0 1(9.1) 0

Shins 1(1.8) 0 0 0 0 0 0 0 2(25.0)

Calves 3(5.5) 1(1.8) 0 0 0 0 0 0 0

Ankles/feet 9(16.4) 11(20.0) 8(11.0) 1(7.1) 1(6.3) 3(16.7) 1(6.7) 1(9.1) 0

Toes 2(3.6) 2(3.6) 1(1.4) 0 1(6.3) 1(5.6) 0 1(9.1) 3(37.5) Abbreviations: SEFIP, Self Estimated Functional Inability because of Pain; NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; KDC, Kibbutz Contemporary Dance Company; KDC2, Kibbutz Contemporary Dance Company 2.

32 33

Table 3.6: Frequency of SEFIP scores ≥ 3 (by style, sex)

Ballet Modern

Location Male Female Male Female n=73 n=103 n=41 n=41 n(%) n(%) n(%) n(%)

Neck 1(1.4) 1(1.0) 0 5(12.2)

Mid-Back 2(2.8) 5(4.9) 3(7.3) 1(2.4)

Elbows 0 0 0 1(2.4)

Lower Back 6(8.2) 9(8.7) 5(12.2) 6(14.6)

Hips 4(5.5) 7(6.8) 3(7.3) 3(7.3)

Posterior Thighs 1(1.4) 5(4.9) 0 1(2.4)

Shoulders 1(1.4) 0 3(7.3) 2(4.9)

Wrists/hands 0 1(1.0) 2(4.9) 0

Anterior Thighs 0 0 0 0

Knees 4(5.5) 4(4.0) 1(2.4) 2(4.9)

Shins 0 1(1.0) 2(4.9) 0

Calves 1(1.4) 3(2.9) 0 0

Ankles/feet 11(15.1) 17(16.3) 4(9.8) 3(7.3)

Toes 1(1.4) 4(3.9) 3(7.3) 3(7.3) Abbreviations: SEFIP, Self Estimated Functional Inability because of Pain

3.5 Numeric Rating Scale Scores: Dance related pain over the last week. Descriptive results of the NRS-11 scores of dance related pain over the last week are presented in Table 3.7. Mean scores for ballet and modern dancers were similar, with ballet dancers reporting a mean score of 4.3 (2.3 SD) average pain over the last week and modern dancers reporting a mean score of 4.5 (2.0 SD) average pain over the last week. Dancers reported scores at all levels of the scale including both extremes of 0 (no pain) as well as 10 (worst possible pain). Overall, the majority of dancers are reporting some degree of pain. The frequency of pain by cut-points along the NRS-11 scale is presented in Table 3.8. Higher frequencies of ballet dancers are reporting scores of “no pain” than modern dancers; however, no modern dancers reported NRS-11 scores higher than 8. Ballet dancers in two companies reported scores of “worst possible pain” (Table 3.7). Overall, the majority of dancers are reporting pain in the range of 1-4 (mild) followed by 5-7 (moderate), 8-10 (severe), and “no pain” ranges respectively. Two exceptions occurred in the Toronto Dance Theatre and the Kibbutz Contemporary Dance Company where dancers reported higher frequencies of pain in the 5-7 range (moderate) followed by the 1-4 (mild), 8-10 (severe), and “no pain” ranges respectively.

Table 3.7: Average dance-related pain over last week, Numeric Rating Scale-11 scores

Mean Median SD Minimum-Maximum Ballet dancers(n=176) 4.3 4.0 2.3 0-10

National Ballet of Canada(n=55) 4.7 5.0 2.0 0-10 Royal Swedish Ballet(n=55) 4.3 3.0 2.6 0-9 Royal Danish Ballet(n=67) 3.9 3.0 2.3 0-10

Modern dancers(n=82) 4.5 5.0 2.0 0-8

Toronto Dance Theatre(n=14) 5.1 5.0 1.9 1-8 Cullberg Ballet(n=16) 3.8 3.0 2.0 1-8 Batsheva Dance Company(n=18) 4.0 3.5 2.0 1-8 Ensemble Batsheva (n=15) 4.3 4.0 1.8 2-7 Kibbutz Contemporary Dance 5.0 6.0 2.3 0-8 Company(n=11) Kibbutz Contemporary Dance 6.0 6.0 1.4 4-8 Company 2 (n=8) Abbreviations: SD, Standard deviation.

Table 3.8: Pain severity using Numeric Rating Scale-11 cut-points. Average dance- related pain over last week.

NRS-11 score: {0} {1-4} {5-7} {8-10} n(%) n(%) n(%) n(%)

Ballet dancers (n=176) 8(4.5) 93(52.9) 61(34.7) 14(7.9)

National Ballet of Canada (n=55) 1(1.8) 25(45.4) 25(45.4) 4(7.3) Royal Swedish Ballet (n=55) 4(7.3) 26(38.3) 19(34.5) 6(10.9) Royal Danish Ballet (n=67) 4(6.0) 42(62.8) 17(25.4) 4(6.0)

Modern dancers (n=82) 1(1.2) 39(47.6) 37(45.1) 5(6.1)

Toronto Dance Theatre (n=14) 0 5(35.6) 8(57.1) 1(7.1) Cullberg Ballet (n=16) 0 11(68.9) 4(25.1) 1(6.3) Batsheva Dance Company (n=18) 0 11(61.1) 6(33.4) 1(5.6) Ensemble Batsheva (n=15) 0 9(60.0) 6(40.0) 0 Kibbutz Contemporary Dance Company (n=11) 1(9.1) 2(18.2) 7(63.7) 1(9.1) Kibbutz Contemporary Dance Company 2 (n=8) 0 1(12.5) 6(75.0) 1(12.5) Abbreviations: NRS, Numeric Rating Scale. Categories based on cut points50: {0}= no pain, {1-4}= mild, {5-7}= moderate, {8-10}= severe

3.6 Current treatment The majority of dancers reported they were currently receiving treatment for dance- related pain (Table 3.9). Dancers in the TDT were the only group in which less than 50% of dancers reported currently receiving treatment for their dance-related pain. The types of healthcare practitioners that these dancers were receiving care from are reported in Table 3.10 and in aggregate format by style in Table 3.11. Some types of healthcare utilized by dancers are country dependent. Naprapaths were utilized only by Swedish dancers. Osteopaths were utilized by Swedish and Danish dancers. Athletic therapists were utilized by Canadian and Swedish ballet dancers. Israeli dancers did not utilize chiropractic care. The majority of ballet and modern dancers receiving treatment are utilizing massage therapy and physiotherapy followed by acupuncture. Very few ballet dancers and no modern dancers were receiving treatment from a medical doctor for dance-related pain. Where dancers are receiving treatment is detailed in Table 3.12. Modern dancers are more likely to solely receive care off-site than ballet dancers with the exception of the KDC and KDC2 dancers.

Table 3.9: Dancers currently receiving treatment for dance-related pain.

Dancers Currently Receiving Treatment n(%)

Ballet dancers (n=177) 108(61.0)

National Ballet of Canada (n=55) 33(60.0) Royal Swedish Ballet (n=55) 35(63.6) Royal Danish Ballet (n=68) 40(58.8)

Modern dancers (n=82) 60(73.2)

Toronto Dance Theatre (n=14) 6(42.9) Cullberg Ballet (n=16) 9(56.3) Batsheva Dance Company (n=18) 16(88.9) Ensemble Batsheva (n=15) 10(66.7) Kibbutz Contemporary Dance Company 11(100.0) (n=11) Kibbutz Contemporary Dance Company 2 8(100.0) (n=8)

Table 3.10: Treatment from Healthcare Practitioners (only dancers currently receiving treatment)

NBC RSB RDB TDT CUL BAT ENS KDC KDC2 N=33 N=35 N=40 N=6 N=9 N=16 N=10 N=11 N=8 n(%) n(%) n(%) n(%) n(%) n(%) n(%) n(%) n(%) Acupuncturist 4(12.1) 9(25.7) 6(15.0) 2(33.3) 1(11.1) 9(56.3) 4(40.0) 5(45.5) 2(25.0)

Athletic Therapist 17(51.5) 2(5.7) 0 0 0 0 0 0 0

Chiropractor 2(6.1) 7(20.0) 2(5.0) 2(33.3) 1(11.1) 0 0 0 0

Massage Therapist 29(87.9) 15(42.9) 25(62.5) 4(66.7) 5(55.6) 6(37.5) 7(70.0) 11(100.0) 7(87.5)

Medical Doctor 3(9.1) 3(8.6) 5(12.5) 0 0 0 0 0 0

Medical Specialist 0 1(2.9) 1(2.5) 0 0 0 0 0 0

Naturopath 2(6.1) 1(2.9) 1(2.5) 1(16.7) 1(11.1) 0 0 0 0

Naprapath n/a 10(28.6) n/a n/a 1(11.1) n/a n/a n/a n/a

Osteopath 2(5.7) 7(17.5) 0 6(66.7) 0 0 0 0

Physiotherapist 24(72.7) 15(42.9) 28(70.0) 2(33.3) 2(22.2) 12(75.0) 9(90.0) 9(81.8) 7(87.5)

Psychologist/ 2(6.1) 0 4(10.0) 1(16.7) 2(22.2) 1(6.3) 1(10.0) 0 0 Psychiatrist/ Counselor

Other 3(9.4) 0 4(10.0) 2(33.3) 1(11.1) 7(43.8) 2(20.0) 1(9.1) 0 Includes only dancers who responded that they were receiving treatment for dance-related pain. Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; KDC, Kibbutz Contemporary Dance Company; KDC2, Kibbutz Contemporary Dance Company 2; n/a, not applicable.

39 40

Table 3.11: Frequency of Treatment from Healthcare Practitioners (only dancers currently receiving treatment)

Ballet Modern N=108 N=60 n(%) n(%)

Acupuncturist 19(17.4) 23(38.3)

Athletic Therapist 19(17.4) 0

Chiropractor 11(10.1) 3(5.0)

Massage Therapist 69(63.3) 40(66.7)

Medical Doctor 11(10.1) 0

Medical Specialist 2(1.8) 0

Naturopath 4(3.7) 2(3.3)

Naprapath 10(9.2) 1(1.7)

Osteopath 16(14.7) 6(10.0)

Physiotherapist 68(62.4) 41(68.3)

Psychologist/ 6(5.5) 5(8.3) Psychiatrist/ Counselor

Other 7(6.5) 13(21.7) Includes only dancers who responded that they were receiving treatment for dance- related pain.

41 Table 3.12: Site of Current Treatment (only dancers currently receiving treatment)

On-site Off-site Both n(%) n(%) n(%)

Ballet (N=107) 49(45.8) 11(10.3) 47(43.9)

National Ballet of Canada (N=34) 11(32.4) 4(11.8) 19(55.9) Royal Swedish Ballet (N=34) 18(52.9) 6(17.6) 10(29.4) Royal Danish Ballet (N=39) 20(51.3) 1(2.6) 18(46.2)

Modern (N=59) 19(32.2) 33(55.9) 7(11.9)

Toronto Dance Theatre (N=6) 0 6(100.0) 0 Cullberg Ballet (N=8) 0 7(87.5) 1(12.5) Batsheva Dance Company (N=16) 2(12.5) 10(62.5) 4(25.0) Ensemble Batsheva (N=10) 0 9(90.0) 1(10.0) Kibbutz Contemporary Dance Company (N=11) 9(81.8) 1(9.1) 1(9.1) Kibbutz Contemporary Dance Company 2 (N=8) 8(100.0) 0 0 Includes only dancers who responded that they were receiving treatment for dance-related pain.

3.7 Pain Medication Use Frequency of pain medication use is reported in Table 3.13. Canadian ballet (58.2%) and modern (50.0%) dancers report higher use of non-prescription pain medications in the past week compared to other countries. Amongst ballet dancers, the Canadian dancers (20.0%) also reported the highest frequency of prescription pain medication use. There was one reported use of prescription pain medication use in modern dancers.

Table 3.13: Pain medication use in last week (all dancers)

Non-prescription pain Prescription pain medication use in last week medication use in last n(%) week n(%)

Ballet dancers (N=175) 69(39.4) 25(14.3)

National Ballet of Canada 32(58.2) 11(20.0) (n=55) Royal Swedish Ballet (n=53) 20(37.7) 10(18.5) Royal Danish Ballet (n=67) 17(25.4) 4(6.0)

Modern dancers (n=82) 18(22.0) 1(1.2)

Toronto Dance Theatre 7(50.0) 0 (n=14) Cullberg Ballet (n=16) 4(25.0) 0 Batsheva Dance Company 4(22.2) 0 (n=18) Ensemble Batsheva (n=15) 0 0 Kibbutz Contemporary 1(9.1) 1(9.1) Dance Company (n=11) Kibbutz Contemporary 2(25.0) 0 Dance Company 2 (n=8)

3.8 Injury Prevalence

Dancers’ current self-reported injury status is detailed in Table 3.14. Almost ¼ of all dancers are reporting a persistent injury. Four dancers reported injuries that were not dance-related and have been removed. The point prevalence of self-reported injury (Outcome 1) is reported with 95% confidence intervals in Table 3.15. (Non-dance related injuries have been removed from this table). The aggregate point prevalence of self-reported injury (SRI) for ballet dancers was 54.8%. This ranged from 47.1% in the Royal Danish Ballet to 59.3% in the Royal Swedish Ballet. The aggregate point prevalence of SRI for modern dancers is 46.3%. This ranged from 9.1% in the Kibbutz Contemporary Dance Company to 66.7% in the Batsheva Dance Company.

The point prevalence of SEFIP ≥3 injury (Outcome 2) is reported with 95% confidence intervals in Table 3.16. The aggregate point prevalence of SEFIP ≥3 injury in ballet dancers is 38.8%. This ranged from 33.8% in the Royal Danish Ballet to 47.3% in the Royal Swedish Ballet. The aggregate point prevalence of SEFIP ≥3 injury in modern dancers is 45.1%. This ranged from 20.0% in the Ensemble Batsheva to 100.0% in the Kibbutz Contemporary Dance Company 2.

44 Table 3.14: Current Injury Status

Injured Recovering from an Persistent Not Injury Injury Injured n(%) n(%) n(%) n(%)

Ballet Dancers (n=177) 17(9.6) 38(21.5) 44(24.9) 78(44.1)

National Ballet of Canada (n=55) 4(7.3) 15(27.3) 13(23.6) 23(41.8) Royal Swedish Ballet (n=54) 7(13.0) 8(14.8) 19(35.2) 20(37.0) Royal Danish Ballet (n=68) 6(8.8) 15(22.1) 12(17.6) 35(51.5)

Modern Dancers (n=82) 9(11.0) 11(13.4) 19(23.2) 43(52.4)

Toronto Dance Theatre (n=14) 2(14.3) 0 5(35.7) 7(50.0) Cullberg Ballet (n=16) 2(12.5) 2(12.5) 3(18.8) 9(56.3) Batsheva Dance Company (n=18) 2(11.1) 6(33.3) 4(22.2) 6(33.3) Ensemble Batsheva (n=15) 2(13.3) 3(20.0) 4(26.7) 6(40.0) Kibbutz Contemporary Dance 0 0 1(9.1) 10(91.9) Company (n=11) Kibbutz Contemporary Dance 1(12.5) 0 2(25.0) 5(62.5) Company 2 (n=8)

45 Table 3.15: Point prevalence of Self Reported Injury Prevalence of Dance-related MSK Injury %(95%CI)

Ballet dancers (n=177) 54.8 (47.7 – 62.1)

National Ballet of Canada (n=55) 58.2 (45.1 – 71.2) Royal Swedish Ballet (n=54) 59.3 (46.1 – 72.4) Royal Danish Ballet (n=68) 47.1 (35.2 - 58.9)

Modern dancers (n=82) 46.3 (35.5 – 57.1)

Toronto Dance Theatre (n=14) 42.9 (16.9 – 68.8) Cullberg Ballet (n=16) 43.7 (19.4 – 68.1) Batsheva Dance Company (n=18) 66.7 (44.9 – 88.4) Ensemble Batsheva (n=15) 60 (35.2 – 84.8) Kibbutz Contemporary Dance Company 9.1 (0– 26.1) (n=11) Kibbutz Contemporary Dance Company 2 37.5 (3.9 – 71.0) (n=8)

Table 3.16: Point prevalence of SEFIP≥3 Injury Prevalence of SEFIP≥3 Injury %(95%CI)

Ballet dancers (n=178) 38.8 (30.9 – 45.1)

National Ballet of Canada (n=55) 36.4 (23.3 – 48.7) Royal Swedish Ballet (n=55) 47.3 (33.8 – 60.2) Royal Danish Ballet (n=68) 33.8 (22.7 – 45.3)

Modern dancers (n=82) 45.1 (34.2 – 55.8)

Toronto Dance Theatre (n=14) 35.7 (10.9 – 61.1) Cullberg Ballet (n=16) 31.3 (8.3 – 53.7) Batsheva Dance Company (n=18) 55.6 (33.1 – 78.9) Ensemble Batsheva (n=15) 20.0 (0 – 40.2) Kibbutz Contemporary Dance Company (n=11) 54.5 (25.6– 84.4) Kibbutz Contemporary Dance Company 2 (n=8) 100.0 (100.0 – 100.0) Abbreviations: SEFIP, Self Estimated Functional Inability because of Pain

3.9 Factors associated with self-reported dance-related musculoskeletal injuries (SRI) in dancers.

3.9.1 Univariate analysis (crude analysis) The results of the univariate analysis for ballet dancers are reported in Table 3.17. The frequency of injury for each variable considered for the multivariable analysis is reported with associated odds ratios and 95% confidence intervals. The variables that have met the criteria to be included in the regression analysis are sex, low body weight, low income, rank, number of years dancing total, number of years dancing professionally, number of years dancing in present company, and age. The univariate analyses suggest that females are less likely to report injury than males; dancers with low body weight are less likely to report injury than dancers with normal body weight; dancers earning below the low income threshold are less likely to report injury than dancers above the threshold. Soloist or principal dancers are more likely to report an injury than corps de ballet dancers whereas apprentices are less likely. Dancers in the three quartiles above 22 years of age were more likely to report an injury than younger dancers in the reference age group of ≤22 years. Dancers dancing more than three years professionally (all three quartiles) were more likely to report injury than the reference group of dancers dancing three or fewer years professionally. Dancers who reported dancing 17-23 years total and ≥24 years total were more likely to report an injury than dancers who danced ≤11 years total. Dancers who had danced 7-12 years or ≥13 years in the present company are more likely to report an injury than those dancers who had danced ≤2 years in the present company. The variables company and country were not significantly associated with self-reported injury.

The univariate analysis for modern dancers is presented in Table 3.18. The Kibbutz Contemporary Dance Company dancers were less likely to report an injury than the Toronto Dance Theatre dancers (OR = 0.10). The variables sex, low body weight, low income, country, number of years dancing total, number of years dancing professionally, number of years in present company, and age were not significantly associated with self-reported injury in the univariate analysis. Due to the fact that no other variables met the criteria for inclusion in the regression analysis, multivariable analysis was not performed for modern dancers.

Table 3.17: Univariate Analysis Results for Self Reported Injury(ballet dancers only)

Variable Not injured Injured OR 95% CI p-value n(%) n(%) Sex: Female 52(66.7) 52(52.5) 0.55 0.30 – 1.02 0.06

Age ≤22 years 26(33.3) 16(16.3) 1.00 23-26 years 20(25.6) 25(25.5) 2.03 0.86 – 4.78 0.10 27-32 years 15(19.2) 27(27.6) 2.93 1.21 – 7.10 0.02 ≥33 years 17(21.8) 30(30.6) 2.87 1.21 – 6.79 0.02

Low body weight (<18.5 BMI) 31(40.3) 26(27.7) 0.57 0.30 – 1.08 0.08

Low income: Below cut-off 9(11.5) 2(2.1) 0.16 0.03 – 0.77 0.02

Rank: Corps 49(62.8) 48(48.5) 1.00 Apprentice 8(10.3) 3(3.0) 0.38 0.10 – 1.53 0.17 Soloist/principal 21(26.9) 48(48.5) 2.33 1.22 – 4.47 0.01

Number of years dancing total ≤11 years 22(28.6) 16(16.5) 1.00 12-16 years 21(27.3) 22(22.7) 1.44 0.60 – 3.47 0.42 17-23 years 18(23.4) 30(30.9) 2.29 0.96 – 5.47 0.06 ≥24 years 16(20.8) 29(29.9) 2.49 1.03 – 6.05 0.04

Number of years dancing professionally ≤3 years 23(29.5) 12(12.2) 1.00 4-8 years 20(25.6) 28(28.6) 2.68 1.09 – 6.62 0.03 9-15.4 years 17(21.8) 32(32.7) 3.61 1.45 – 8.99 0.006 ≥15.5 years 18(23.1) 26(26.5) 3.04 1.10 – 6.95 0.01

Number of years in present company ≤2 years 22(28.2) 17(17.4) 1.00 3-6 years 23(29.5) 23(23.5) 1.29 0.55 – 3.05 0.56 7-12 years 14(18.0) 30(30.6) 2.77 1.13 – 6.79 0.03 ≥13 years 19(24.4) 28(28.6) 1.91 0.81 – 4.51 0.03

Company: National Ballet of Canada 23(41.8) 32(58.2) 1.00 Royal Swedish Ballet 20(37.0) 34(63.0) 1.22 0.57 – 2.64 0.61 Royal Danish Ballet 35(51.5) 33(48.5) 0.68 0.33 – 1.39 0.28

48 Table 3.17: Univariate Analysis Results for Self Reported Injury(ballet dancers only)

Variable Not injured Injured OR 95% CI p-value n(%) n(%)

Country: Canada 23(29.5) 32(32.3) 1.00 Sweden 20(25.6) 34(34.3) 1.22 0.57 – 2.64 0.61 Denmark 35(44.9) 33(33.3) 0.68 0.33 – 1.39 0.29 * Abbreviations: OR, odds ratio; CI, confidence interval, BMI, body mass index. *Israel not included as there were no participating ballet companies in Israel.

Table 3.18: Univariate Analysis Results for Self Reported Injury (modern dancers only)

Variable Not injured Injured OR 95% CI p-value n(%) n(%) Sex: Female 22(51.2) 19(48.7) 0.91 0.38 – 2.16 0.83

Age ≤21 years 12(29.3) 7(18.0) 1.00 22-24 years 6(14.6) 10(25.6) 2.86 0.72 – 11.31 0.13 25-27 years 10(24.4) 13(33.3) 2.23 0.64 – 7.74 0.21 ≥28 years 13(31.7) 9(23.1) 1.19 0.34 – 4.19 0.79

Low body weight (<18.5 BMI) 2(4.9) 1(2.6) 0.51 0.05 – 5.90 0.59

Low income: Below cut-off 9(20.9) 7(18.0) 0.16 0.28 – 2.48 0.73

Number of years dancing total ≤8 years 11(26.2) 9(23.1) 1.00 9-12 years 10(23.8) 10(25.6) 1.22 0.35 – 4.24 0.75 13-18 years 9(21.4) 10(25.6) 1.36 0.39 – 4.79 0.63 ≥19 years 12(28.6) 10(25.6) 1.02 0.30 – 4.24 0.98

Number of years dancing professionally ≤2 years 8(19.1) 10(25.6) 1.00 3-4 years 10(23.8) 4(10.3) 0.32 0.07 – 1.42 0.13 5-8 years 11(26.2) 13(33.3) 0.95 0.28 – 3.23 0.93 ≥9 years 13(31.0) 12(30.8) 0.74 0.22 – 2.49 0.63

Number of years in present company ≤2 years 19(44.2) 18(46.2) 1.00 3-6 years 12(27.9) 11(28.2) 0.97 0.34 – 2.74 0.95 ≥7 years 12(27.9) 10(25.6) 0.88 0.31 – 2.54 0.81

Company: Toronto Dance Theatre 7(50.0) 7(50.0) 1.00 Cullberg Ballet 9(56.3) 7(43.8) 0.78 0.18 – 3.28 0.73 Batsheva Dance Company 6(33.3) 12(66.7) 2.00 0.48 – 8.40 0.34 Ensemble Batsheva 6(40.0) 9(60.0) 1.50 0.34 – 6.54 0.59 Kibbutz Dance Company 10(90.9) 1(9.1) 0.10 0.01 – 1.01 0.05 Kibbutz Dance Company 2 5(62.5) 3(37.5) 0.60 0.10 – 3.53 0.57

50 Table 3.18: Univariate Analysis Results for Self Reported Injury (modern dancers only)

Variable Not injured Injured OR 95% CI p-value n(%) n(%)

Country: Canada 7(16.3) 7(18.0) 1.00 Sweden 9(20.9) 7(18.0) 0.78 0.18 – 3.28 0.73 Israel 27(62.8) 25(64.1) 0.93 0.28 – 3.02 0.90 * Abbreviations: OR, odds ratio; CI, confidence interval, BMI, body mass index. *Denmark not included as there were no participating modern companies in Denmark.

3.9.2 Multivariable analysis (logistic regression) The model for the multivariable analysis for ballet dancers was created based on the results of the univariate analysis. Spearman’s correlational coefficient was used to determine correlation between the continuous variables. Years dancing professionally, years dancing total, years dancing in present company, and age were all highly correlated with each other (ρ > 0.80). I have chosen to include only years dancing professionally in the multivariable model. This variable best represents the professional dancers’ exposure to dance at the elite professional level and most likely has less variability in the exposure than years dancing total.

The variables included in the multivariable analysis are: sex, low body weight, years dancing professionally, low income, and rank.

The results of the logistic regression analysis for ballet dancers are reported in Table 3.19. The variables low body weight, years dancing professionally, and low income were all removed from the model via backwards stepwise regression. Soloist and principal dancers were more likely to report an injury than dancers in the corps de ballet (OR = 2.44). Female dancers were less likely to report an injury than male dancers, but the results are not statistically significant.

51 Table 3.19: Final Model for Logistic Regression Analysis. Factors Associated with Self Reported Injury (ballet dancers only) Variable β OR 95% CI p-value

Sex (female) -0.55 0.58 0.30 – 1.11 0.07 Rank: Corps de ballet 1.00 Apprentice -0.87 0.42 0.10 – 1.69 0.22 Soloist/principal 0.89 2.44 1.25 – 4.78 0.009 Intercept 0.23

Abbreviations: β, beta; OR, odds ratio; CI, confidence interval, BMI, body mass index.

3.10 Factors associated with SEFIP score of ≥3.

3.10.1 Univariate analysis (crude analysis) The results of the univariate analysis for ballet dancers are reported in Table 3.20. The frequency of injury for each variable considered for the multivariable analysis is reported with associated odds ratios and 95% confidence intervals. The variables that have met the criteria to be included in the regression analysis are low income, rank, number of years dancing total, number of years dancing professionally, number of years dancing in the present company, and age. The univariate analyses suggest that ballet dancers earning below the low income threshold are less likely to report injury than dancers above the threshold. Soloist or principal dancers are more likely to report a SEFIP score ≥3 than corps de ballet dancers whereas apprentices are less likely to report a SEFIP score ≥3. Dancers in the three quartiles above 22 years of age were more likely to report a SEFIP score ≥3 than younger dancers in the reference age group of ≤22 years. Additionally, dancers dancing 9-15.4 years professionally as well as ≥15.5 years professionally were more likely to report a SEFIP score ≥3 than the reference group of dancers dancing three or fewer years professionally. Dancers who reported dancing 17-23 years total and ≥24 years total were more likely to report a SEFIP score ≥3 than dancers who danced ≤11 years total. Dancers who had danced 7-12 years or ≥13 years in the present company are more likely to report a SEFIP score ≥3 than those dancers who had danced ≤2 years in the present company. The variables sex, low body weight, company, and country were not significantly associated with a SEFIP score ≥3.

The univariate analysis for modern dancers is presented in Table 3.21. The variables that have met the criteria to be included in the regression analysis are low income, age, and number of years dancing professionally. The univariate analyses suggest that modern dancers with low income are more likely to report a SEFIP score ≥3 than dancers above the low income threshold. Modern dancers between 22-24 years of age are less likely to report a SEFIP score ≥3 than dancers less than 21 years of age; dancers dancing more than 3-4 years professionally are less likely to report a SEFIP score ≥3 than dancers dancing two years or less professionally. The variables sex, low body weight, number of years dancing total, number of years dancing in present company, and country were not significantly associated with injury. Due to the small sample sizes of each individual modern dance company, the company variable could not be analyzed as the validity of the model fit was questionable for this variable.

Table 3.20: Univariate Analysis for SEFIP score of ≥3 (ballet dancers only)

Variable SEFIP<3 SEFIP≥3 OR 95% CI p-value n(%) n(%) Sex: Female 64(59.3) 39(57.4) 0.93 0.50 – 1.71 0.80

Age ≤22 years 34(31.5) 8(11.9) 1.00 23-26 years 30(27.8) 15(22.4) 2.13 0.79 – 5.71 0.14 27-32 years 25(23.2) 17(25.4) 2.89 1.08 – 7.75 0.04 ≥33 years 19(17.6) 27(40.3) 6.04 2.29 – 15.91 0.0003

Low body weight (<18.5 BMI) 34(33.0) 22(32.8) 0.99 0.52 – 1.91 0.98

Low income: Below cut-off 9(8.3) 2(3.0) 0.35 0.07 – 1.66 0.19

Rank: Corps 64(59.3) 32(47.1) 1.00 Apprentice 10(9.3) 1(1.5) 0.20 0.03 – 1.63 0.13 Soloist/principal 34(31.5) 35(51.5) 2.06 1.09 – 3.89 0.03

Number of years dancing total ≤11 years 30(28.0) 8(12.1) 1.00 12-16 years 35(32.7) 8(12.1) 0.86 0.29 – 2.56 0.78 17-23 years 24(22.4) 24(36.4) 3.75 1.43 – 9.83 0.07 ≥24 years 18(16.8) 26(39.4) 5.42 2.02 – 14.50 0.0008

Number of years dancing professionally ≤3 years 28(25.9) 7(10.5) 1.00 4-8 years 36(33.3) 12(17.9) 1.33 0.46 – 3.83 0.59 9-15.4 years 24(22.2) 25(37.3) 4.17 1.53 – 11.32 0.005 ≥15.5 years 20(18.5) 23(34.3) 4.60 1.66 – 12.79 0.003

Number of years in present company ≤2 years 32(29.6) 7(10.5) 1.00 3-6 years 30(27.8) 16(23.9) 2.44 0.88 – 6.75 0.09 7-12 years 24(22.2) 20(29.9) 3.81 1.39 – 10.46 0.01 ≥13 years 22(20.4) 24(35.8) 4.99 1.83 – 13.58 0.002

Company: National Ballet of Canada 35(63.6) 20(36.4) 1.00 1.00 – 1.00 Royal Swedish Ballet 29(52.7) 26(47.3) 1.57 0.73 – 3.37 0.25 Royal Danish Ballet 45(67.2) 22(32.8) 0.86 0.40 – 1.81 0.68

54 Table 3.20: Univariate Analysis for SEFIP score of ≥3 (ballet dancers only)

Variable SEFIP<3 SEFIP≥3 OR 95% CI p-value n(%) n(%)

Country: Canada 35(32.1) 20(29.4) 1.00 Sweden 29(26.6) 26(38.2) 1.57 0.73 – 3.37 0.25 Denmark 45(41.3) 22(32.4) 0.86 0.40 – 1.81 0.68 *

Abbreviations: SEFIP, Self Estimated Functional Inability because of Pain; OR, odds ratio; CI, confidence interval; BMI, body mass index. *Israel not included as there were no participating ballet companies in Israel.

Table 3.21: Univariate Analysis for SEFIP score of ≥3(modern dancers only)

Variable SEFIP<3 SEFIP≥3 OR 95% CI p-value n(%) n(%) Sex: Female 23(51.1) 18(48.7) 0.91 0.38 – 2.16 0.82

Age ≤21 years 8(18.2) 11(30.6) 1.00 22-24 years 11(25.0) 5(13.9) 0.33 0.08 – 1.34 0.12 25-27 years 13(29.6) 10(27.8) 0.56 0.16 – 1.91 0.35 ≥28 years 12(27.3) 10(27.8) 0.61 0.18 – 2.09 0.43

Low body weight (<18.5 BMI) 1(2.3) 2(5.4) 2.40 0.21 – 27.59 0.48

Low income: Below cut-off 6(13.3) 10(27.0) 2.41 0.78 – 7.41 0.13

Number of years dancing total ≤8 years 9(25.0) 11(33.3) 1.00 9-12 years 13(36.1) 7(21.2) 0.44 0.12 – 1.57 0.21 13-18 years 11(30.6) 8(24.2) 0.60 0.17 – 2.11 0.42 ≥19 years 3(8.3) 7(21.2) 1.91 0.38 – 9.59 0.43

Number of years dancing professionally ≤2 years 8(18.2) 10(27.0) 1.00 3-4 years 12(27.3) 2(5.4) 0.13 0.02 – 0.77 0.03 5-8 years 11(25.0) 13(35.1) 0.95 0.28 – 3.23 0.93 ≥9 years 13(29.6) 12(32.4) 0.74 0.22 – 2.49 0.63

Number of years in present company ≤2 years 22(48.9) 15(40.5) 1.00 3-6 years 12(26.7) 11(29.7) 1.34 0.47 – 3.84 0.58 ≥7 years 11(24.4) 11(29.7) 1.47 0.51 – 4.24 0.48

Country: Canada 9(20.0) 5(13.5) 1.00 Sweden 11(24.4) 5(13.5) 0.82 0.18 – 3.74 0.80 Israel 25(55.6) 27(51.9) 1.94 0.57 – 6.59 0.29 * Abbreviations: SEFIP, Self Estimated Functional Inability because of Pain; OR, odds ratio; CI, confidence interval, BMI, body mass index. *Denmark not included as there were no participating modern companies in Denmark.

3.10.2 Multivariable analysis (logistic regression)

Identical methodology was used as for the previous analysis of self reported injury, but this time using the outcome variable of SEFIP score of ≥3. The model for the multivariable analysis for ballet dancers was created based on the results of the univariate analysis. The variables included in this model are: Low income, rank, and number of years dancing professionally.

The results of the logistic regression analysis for ballet dancers are reported in Table 3.22. The variables low income and rank were removed from the model via backwards stepwise regression. Ballet dancers dancing 9-15.4 years professionally were more likely to have a SEFIP score of ≥3 as ballet dancers dancing ≤3 years professionally (OR = 4.0). This association strengthened with dancers dancing professionally ≥15.5 years (OR = 4.4).

Table 3.22 Final Model for Logistic Regression Analysis. Factors Associated with SEFIP ≥3 (ballet dancers) Variable β OR 95% CI p-value Number of years dancing professionally: ≤3 years 1.00 1.00 4-8 years 0.29 1.33 0.46 – 3.83 0.59 9-15.4 years 1.39 4.00 1.47 – 10.91 0.007 ≥15.5 years 1.48 4.40 1.58 – 12.28 0.005 Intercept -1.39

Abbreviations: β, beta; SEFIP, Self Estimated Functional Inability because of Pain; OR, odds ratio; CI, confidence interval.

Lastly, a model was created based on the univariate analysis for modern dancers only.

The variables included in this model are: Low income and number of years dancing professionally.

No variables remained in the model after the logistic regression analysis.

3.12 Characteristics of Prevalent Injuries

3.12.1 Body region injured If dancers had more than one body region injured, they were asked to report the most problematic body region injured. The same body regions were listed as for the SEFIP. The results for current most problematic body region injured for dancers are reported stratified by style and sex in Table 3.23. Results are reported stratified by dance company in Table 3.24.

A similar pattern is noted for all male and female ballet dancers (Table 3.23). The ankles/feet region has the highest percentage of reported “most problematic injury” followed by knees. This is followed by either hip or low back regions. Amongst ballet dancers, there was only one reported upper limb region (shoulders) being a “most problematic injury” and no ballet dancer reported the neck, elbows, wrists/hands, anterior thighs, shins, or toes as being the “most problematic injury”.

No similar pattern is noted between the modern dance companies for the “most problematic injury.”(Table 3.24) In contrast to ballet dancers, neck injuries are reported amongst modern dancers. The neck is the most frequent body region reported for “most problematic injury” in the Batsheva Dance Company (45.5%) and Ensemble Batsheva (40.0%). The most frequent region reported amongst Toronto Dance Theatre dancers is the shoulder region (33.3%). Amongst the Cullberg Ballet dancers, the knees were the most frequently reported region of injury (37.5%). No modern dancers reported a problematic injury in the elbows, wrists/hands, anterior thighs, or shins.

Table 3.23: Body Region Injured (current most problematic injury of injured dancers) by style and sex.

Ballet Modern Body Region Male Female Male Female n=40 n=56 n=19 n=20 n(%) n(%) n(%) n(%) Neck 0 0 4(21.1) 6(30.0)

Shoulders 0 1(1.8) 2(10.5) 1(5.0)

Elbows 0 0 0 0

Wrists/hands 0 0 0 0

Upper back 1(2.5) 2(3.6) 1(5.3) 0

Lower back 4(10.0) 6(10.7) 5(26.3) 4(20.0)

Hips 5(12.5) 6(10.7) 3(15.8) 1(5.0)

Ant. Thighs 0 0 0 0

Post. Thighs 1(2.5) 3(5.4) 0 2(10.0)

Knees 7(17.5) 13(23.2) 0 3(15.0)

Shins 0 0 0 0

Calves 0 1(1.8) 1(5.3) 0

Ankles/Feet 22(55.0) 23(41.1) 3(15.8) 1(5.0)

Toes 0 0 0 2(10.0) Only dancers reporting injury were included. All non-dance related injuries have been removed.

Table 3.24: Body Region Injured (current most problematic injury of injured dancers) by company. Ballet Companies Modern Companies Body Region NBC RSB RDB TDT CUL BAT ENS N=32 N=33 N=32 N=6 N=8 N=11 N=10 n(%) n(%) n(%) n(%) n(%) n(%) n(%)

Neck 0 0 0 1(16.7) 0 5(45.5) 4(40.0)

Shoulders 0 0 1(3.1) 2(33.3) 0 0 1(10.0)

Elbows 0 0 0 0 0 0 0

Wrists/hands 0 0 0 0 0 0 0

Upper back 1(3.1) 0 2(6.3) 0 1(12.5) 0 0

Lower back 3(9.4) 4(12.1) 4(12.5) 0 2(25.0) 2(18.2) 3(30.0)

Hips 3(9.4) 6(18.2) 2(6.3) 1(16.7) 0 1(9.1) 2(20.0)

Ant. Thighs 0 0 0 0 0 0 0

Post. Thighs 0 3(9.1) 1(3.1) 1(16.7) 1(12.5) 0 0

Knees 6(18.8) 7(21.2) 7(21.9) 0 3(37.5) 0 0

Shins 0 0 0 0 0 0 0

Calves 1(3.1) 0 0 1(16.7) 0 0 0

Ankles/Feet 18(56.3) 12(36.4) 15(46.9) 0 1(12.5) 3(27.3) 0

Toes 0 1(3.0) 0 0 0 0 0 Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related injuries have been removed.

3.12.2 Injury Duration The majority of male and female ballet and modern dancers are reporting chronic injuries, particularly of ≥ 6 months duration (Table 3.25). Fifty percent of female ballet dancers, 51.3% of male ballet dancers and 60.0% of female modern dancers reported current injury of ≥ 6 months duration. The frequency of ≥ 6 months duration was slightly less in modern male dancers (36.8%) however they had greater frequencies in the 3months - <6 months duration (21.1%) and 29 days - <3months duration (15.8%).

The Ensemble Batsheva was the only company with a higher frequency of injuries in the 8-28 days duration (40.0%) than the ≥ 6 months duration (30.0%) (Table 3.26). The National Ballet of Canada had the highest frequency of injury duration less than 29 days (40.5%). By contrast, the Batsheva Dance Company had no reported injury duration of less than 29 days. The Cullberg Ballet dancers reported injury durations at two extremes with 75.0% in the ≥ 6 months duration and 25.0% in the 1-7 days duration.

Table 3.25 : Duration of Injury (by style and sex) Ballet Modern Male Female Male Female N=39 N=56 N=19 N=20 n(%) n(%) n(%) n(%)

1-7 days 2(5.1) 5(8.9) 2(10.5) 1(5.0)

8-28 days 9(23.1) 9(16.1) 3(15.8) 3(15.0)

29 days - <3months 5(12.8) 5(8.9) 3(15.8) 1(5.0)

3months - <6 months 3(7.7) 9(16.1) 4(21.1) 1(5.0)

≥ 6 months 20(51.3) 28(50.0) 7(36.8) 12(60.0)

Only dancers reporting injury were included. All non-dance related injuries have been removed.

Table 3.26 : Duration of Injury (by company) NBC RSB RDB TDT CUL BAT ENS N=32 N=33 N=33 N=6 N=8 N=11 N=10 n(%) n(%) n(%) n(%) n(%) n(%) n(%)

1-7 days 3(9.4) 0 4(12.1) 1(16.7) 2(25.0) 0 0

8-28 days 10(31.1) 4(12.1) 4(12.1) 1(16.7) 0 0 4(40.0)

29 days - 1(3.1) 3(9.1) 7(21.2) 1(16.7) 0 2(18.2) 2(20.0) <3months

3months - <6 4(12.5) 5(15.2) 3(9.1) 0 0 3(27.3) 1(10.0) months

≥ 6 months 14(43.8) 21(63.6) 15(45.5) 3(50.0) 6(75.0) 6(54.5) 3(30.0)

Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related injuries have been removed.

3.12.3 Injury Severity The highest frequency of reported injury severity was moderate for all injured ballet dancers with 55.3% of injured male ballet dancers and 48.1% of injured female ballet dancers reporting moderate injury severity (Table 3.27). Injured modern dancers had similar high reported frequencies of moderate injury severity with 47.4% of injured male modern dancers and 65.0% of injured female modern dancers reporting moderate injury severity. Severe injury severity was reported by 21.1% of injured male ballet dancers and 27.8% of injured female ballet dancers. Similarly, 21.1% of injured male modern dancers and 25.0% of injured female dancers reported severe injury.

The Royal Danish Ballet and the Cullberg Ballet had the highest frequencies of injured dancers reporting their injuries as severe (Table 3.28). Forty percent of injured dancers in the Royal Danish Ballet and 50.0% of injured dancers in the Cullberg ballet reported severe injury.

3.12.4 Time Off Work in Past Year The majority of injured male and female modern dancers took either no time off from work in the past year or 1 to 7 days off work due to their injuries (Table 3.29). Amongst injured modern dancers, 26.3% of males and 45.0% of females took no time off from work; 42.1% of injured male modern dancers and 30.0% of injured female modern dancers took 1-7 days off from work due to their injuries.

Injured ballet dancers reported higher frequencies of time off work compared to injured modern dancers with 10.3% of injured male ballet dancers and 17.9% of injured female ballet dancers taking between 3 to 6 months off from work compared to 5.3% of injured male modern dancers and 5.0% of injured female modern dancers taking between 3 to 6 months off from work due to their injuries (Table 3.29). No injured modern dancers reported taking more than 6 months off from work due to their injuries. In contrast, 12.8% of injured male ballet dancers and 5.4% of injured female ballet dancers took more than 6 months off from work due to their injuries.

Higher percentages of injured dancers in the Scandinavian ballet companies took longer periods of time off work than injured dancers in the National Ballet of Canada with 27.3% of injured Royal Swedish Ballet Dancers and 16.1% of Royal Danish Ballet dancers taking between 3 to 6 months off from work due to their injuries (Table 3.30). Additionally, 3.0% of injured Royal Swedish Ballet dancers and 16.0% of injured Royal Danish Ballet dancers took more than six months off work due to their injuries. In contrast, 3.1% of injured National Ballet of Canada dancers took 3-6 months off and 6.3% of injured National Ballet of Canada dancers took more than six months off work due to their injuries.

Amongst modern dance companies, no injured dancers took more than 28 days off work with the exception of the Batsheva Dance Company in which 27.3% of injured dancers took between 29 days to 3 months off from work and 18.2% of injured dancers took between three and six months off work due to their injuries (Table 3.30). In the Cullberg Ballet, no dancer took more than one week off from work with 87.5% of injured dancers taking no time off work due to their injuries.

Table 3.27 : Injury Severity (by style and sex)

Ballet Modern Male Female Male Female N=39 N=54 N=19 N=20 n(%) n(%) n(%) n(%)

Minor 9(23.7) 13(24.1) 6(31.6) 2(10.0)

Moderate 21(55.3) 26(48.1) 9(47.4) 13(65.0)

Severe 8(21.1) 15(27.8) 4(21.1) 5(25.0)

Only dancers reporting injury were included. All non-dance related injuries have been removed.

Table 3.28 : Injury Severity (by company) NBC RSB RDB TDT CUL BAT ENS N=31 N=32 N=30 N=6 N=8 N=11 N=10 n(%) n(%) n(%) n(%) n(%) n(%) n(%)

Minor 9(29.0) 5(15.6) 8(26.7) 1(16.7) 1(12.5) 2(18.2) 4(40.0)

Moderate 17(54.8) 20(62.5) 10(33.3) 5(83.3) 3(37.5) 6(54.5) 5(50.0)

Severe 5(16.1) 7(21.9) 12(40.0) 0 4(50.0) (27.3) 1(10.0)

Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related injuries have been removed.

Table 3.29: Time off work due to current injury in past year (by style and sex)

Ballet Modern

Male Female Male Female

N=39 N=56 N=19 N=20

n(%) n(%) n(%) n(%)

None 13(33.3) 16(28.6) 5(26.3) 9(45.0)

1-7 days 5(12.8) 11(19.6) 8(42.1) 6(30.0)

8-28 days 9(23.1) 7(12.5) 3(15.8) 2(10.0)

29 days - <3months 3(7.7) 9(16.1) 2(10.5) 2(10.0)

≥3months - <6 months 4(10.3) 10(17.9) 1(5.3) 1(5.0)

≥6 months 5(12.8) 3(5.4) 0 0

Only dancers reporting injury were included. All non-dance related injuries have been removed.

Table 3.30 : Time off work due to current injury in past year (by company) NBC RSB RDB TDT CUL BAT ENS N=32 N=33 N=31 N=6 N=8 N=11 N=10 n(%) n(%) n(%) n(%) n(%) n(%) n(%) None 11(34.4) 14(42.4) 4(12.9) 3(50.0) 7(87.5) 1(9.1) 2(20.0)

1-7 days 6(18.8) 5(15.2) 5(16.1) 2(33.3) 1(12.5) 3(27.3) 7(70.0)

8-28 days 8(25.0) 2(6.1) 6(19.4) 1(16.7) 0 2(18.2) 1(10.0)

29 days - 4(12.5) 2(6.1) (19.4) 0 0 3(27.3) 0 <3months

≥3months - <6 1(3.1) 9(27.3) 5(16.1) 0 0 2(18.2) 0 months

≥6 months 2(6.3) 1(3.0) 5(16.1) 0 0 0 0 Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related injuries have been removed.

3.12.5 Recurrent Injuries

Dancers were asked whether they have had this current injury previously (recurrent injury). Amongst injured ballet dancers, 48.7% of males and 57.1% of females report recurrent injury (Table 3.31). Amongst injured modern dancers, 68.4% of males and 44.4% of females report recurrent injury. Frequency of reported recurrent injury varied between dance companies. Amongst ballet companies, injured dancers in the Royal Swedish Ballet reported the highest frequency of recurrent injury (72.7%) compared with 54.8% of injured dancers in the Royal Danish Ballet reporting recurrent injury and 34.4% of injured dancers in the National Ballet of Canada reporting recurrent injury (Table 3.32). Reported recurrent injury also varied amongst modern dance companies with 100.0% of injured dancers of the Toronto Dance Theatre reporting recurrent injury compared to 66.7% of injured dancers in the Batsheva Dance Company, 50.0% of dancers in the Ensemble Batsheva and 25.0% of injured dancers in the Cullberg Ballet reporting recurrent injury.

Table 3.31 : Recurrent Injury (by style and sex) Ballet Modern Male Female Male Female N=39 N=56 N=19 N=18 n(%) n(%) n(%) n(%)

No 20(51.3) 24(42.9) 6(31.6) 10(55.6)

Yes 19(48.7) 32(57.1) 13(68.4) 8(44.4) Only dancers reporting injury were included. All non-dance related injuries have been removed.

Table 3.32 : Recurrent Injury (by company) NBC RSB RDB TDT CUL BAT ENS N=32 N=33 N=31 N=6 N=8 N=9 N=10 n(%) n(%) n(%) n(%) n(%) n(%) n(%)

No 21(65.6) 9(27.3) 14(45.2) 0 6(75.0) 3(33.3) 5(50.0)

Yes 11(34.4) 24(72.7) 17(54.8) 6(100.0) 2(25.0) 6(66.7) 5(50.0) Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related injuries have been removed.

3.13 Relationship between SEFIP scores and SRI

The frequency of the highest reported SEFIP score reported by injured and non-injured dancers is reported in Table 3.33. The majority of ballet and modern dancers who have reported being injured do report SEFIP scores of 3 or 4 denoting some degree of functional impairment. Between 30.0% to 36.8% of injured ballet and modern dancers reported injury with a highest SEFIP score of 2 which denotes significant pain but no functional compromise.

The majority of dancers who considered themselves “not injured” had a SEFIP score of 2 or less. However, 13.7% of “not injured” female ballet dancers had a SEFIP score of 3 compared to 7.7% of “not injured” male ballet dancers. Of the “not injured” modern dancers, 33.3% of males and 27.3% of females had a SEFIP score of 3. Overall, 19.8% of all “not injured” dancers had a SEFIP score of 3.

Table 3.33: Highest Reported SEFIP Score for Injured and Non-injured Dancers

Ballet Modern Injured Not Injured Injured Not Injured SEFIP Male Female Male Female Male Female Male Female score N=47 N=52 N=26 N=26 N=20 N=19 N=21 N=22 n(%) n(%) n(%) n(%) n(%) n(%) n(%) n(%) 0 0 0 2(7.7) 0 0 0 0 0 1 4(8.5) 5(9.6) 8(30.8) 19(37.3) 2(10.0) 0 7(33.3) 9(40.9) 2 16(34.0) 16(30.8) 14(53.8) 2(49.0) 6(30.0) 7(36.8) 7(33.3) 7(31.8) 3 18(38.3) 28(53.8) 2(7.7) 7(13.7) 12(60.0) 10(52.6) 7(33.3) 6(27.3) 4 9(19.1) 3(5.8) 0 0 0 2(10.5) 0 0 0 = “very well”; 1 = “some pain but not much problem”; 2 = “pretty much pain but I can handle it”; 3 = “much pain, must avoid some movements”; 4 = “cannot work in the production because of pain”. Abbreviations: SEFIP, Self-Estimated Functional Inability because of Pain

3.14 Reporting of Dance-related Injuries

Frequency of dancers who have not reported their injury is detailed in Table 3.34. The aggregate percentage of ballet dancers who have not reported an injury is 15.5%. Amongst the modern dance companies, the Toronto Dance Theatre has a much higher percentage of dancers not reporting an injury (66.7%) as compared to the other modern dance companies.

Reasons why a dancer has not reported an injury are reported in Table 3.35. All the options given were chosen as reasons for not reporting an injury (Appendix 2, Section D). The four most cited reasons overall for both ballet and modern dancers were: “It did not affect my work”, “Pain is an inherent part of dancing”, “I can cope with the pain”, and “I did not want to stop dancing”.

For those dancers who have reported an injury, the results of to whom dancers are reporting their injury are listed in Table 3.36. Twelve dancers reported to “other” which included: assistant to the artistic director, ballet secretary, choreographer, insurance company, government, stage manager, and teacher.

Table 3.37 reports the frequency of all injuries reported to the local workers’ compensation board or national insurance as a work injury by company. Injuries were reported as work injuries only in the Scandinavian ballet companies and the Batsheva Dance Company in Israel.

Table 3.34: Frequency of non-reported injuries

Injuries not reported by dancers n(%)

Ballet dancers (N=97) 15(15.5)

National Ballet of Canada (N=32) 4(12.5)

Royal Swedish Ballet (N=33) 6(18.2)

Royal Danish Ballet (N=32) 5(15.6)

Modern dancers (n=39) 7(17.9)

Toronto Dance Theatre (N=6) 4(66.7)

Cullberg Ballet (N=8) 1(12.5)

Batsheva Dance Company (N=11) 1(9.1)

Ensemble Batsheva (N=10) 1(10.0)

Only injured dancers. Non-dance related injuries removed.

Table 3.35: Reasons for not reporting an injury.

Reason for not reporting an injury: Ballet Modern N=15 N=7 n(%) n(%)

I did not feel it was important. 3(20.0) 2(28.6)

It did not affect my work. 6(40.0) 5(71.4)

I did not want to be seen as unreliable. 3(20.0) 2(28.6)

Pain is an inherent part of dancing. 5(33.3) 5(71.4)

I did not want to negatively affect the 3(20.0) 1(14.3) production.

I can cope with the pain. 8(53.3) 7(100.0)

I did not want to stop dancing. 4(26.7) 5(71.4)

I did not want to lose a role. 2(13.3) 2(28.6)

I did not want to let my company down. 2(13.3) 2(28.6)

Other 1(7.1) 0 Only injured dancers who stated they did not report their injury are included. Non-dance related injuries removed.

Table 3.36: To whom are dancers reporting their injuries? Ballet dancers Modern dancers

NBC RSB RDB TDT CUL BAT ENS (N=28) (N=27) (N=27) (N=2) (N=7) (N=10) (N=9) n(%) n(%) n(%) n(%) n(%) n(%) n(%)

Rehearsal 22(78.6) 11(40.7) 19(70.4) 1(50.0) 5(71.4) 10(100.0) 9(100.0) Director

Company 7(25.0) 2(7.4) 10(38.5) 1(50.0) 2(28.6) 6(60.0) 1(11.1) Manager

Artistic Director 16(57.1) 13(48.1) 17(65.4) 1(50.0) 5(71.4) 7(70.0) 3(33.3)

Company 24(85.7) 26(96.3) 24(88.9) 0 2(28.6) 10(100.0) 5(55.6) Health Professional

Health 16(57.1) 11(40.7) 5(20.0) 2(100.0) 4(57.1) 3(30.0) 2(22.2) Professional not related to company

Other 5(18.5) 5(18.5) 1(4.0) 1(50.0) 0 0 0

Table 3.37: Injuries Reported as Work Injuries

Injuries reported as work injuries n(%)

Ballet

National Ballet of Canada (N=32) n/a

Royal Swedish Ballet (N=33) 10(30.3)

Royal Danish Ballet (n=32) 16(50.0)

Modern

Toronto Dance Theatre (N=6) 0

Cullberg Ballet (N=8) 0

Batsheva Dance Company (N=10) 3(30.0)

Ensemble Batsheva (N=10) 0

Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related injuries have been removed.

3.15 Dancers’ Attitudes and Perceptions of Injury Tables 3.38 reports dancers’ responses to agree/disagree scales of various attitudinal questions regarding injury and dance-related pain stratified by style and self-reported injury status. The results are summarized in aggregate format for all dancers as follows:

1. The majority of dancers (80.6%) disagree with the statement: “I consider myself injured if I have any pain when I dance.”

2. The majority of dancers agree (70.4%) with the statement “I consider myself injured if I must modify movements when I dance due to pain”. However, a significant number of dancers disagree (29.6%) with this statement, especially those who are not injured.

3. The majority of dancers agree (72.8%) with the statement “I consider myself injured if I miss a company class or rehearsal due to dance-related pain.” However, a significant number of dancers disagree (27.1%) with this statement.

4. The majority of dancers agree (70.8%) with the statement “I consider myself injured if I must take medication due to my dance-related pain.” However, a significant number of dancers disagree (29.2%) with this statement, especially ballet dancers.

5. The majority of dancers agree (56.9%) with the statement, “I consider myself injured if I must seek care from a health-care practitioner for my dance-related pain.” However, a significant number of dancers do disagree (43.1%) with this statement.

6. The majority of dancers agree with the following statements: a. “I consider myself injured if I miss more than one day of work due to dance-related pain.” (Agree: 81.3%; Disagree: 11.7%). Ballet dancers were more likely to disagree with this statement than modern dancers.

b. “I consider myself injured if I have visual signs such as redness or swelling that accompany my pain.” (Agree: 85.1%; Disagree: 14.9%). Modern dancers were more likely to disagree with this statement than ballet dancers.

7. Dancers overwhelmingly agree about the following two statements: a. “I consider myself injured if I a m unable to participate in a performance due to dance- related pain.” (Agree: 96.8%; Disagree: 3.2%) b. “I consider myself injured if I must go to the hospital due to my dance-related pain.” ( Agree: 97.3%; Disagree: 2.7%)

Table 3.38: Responses to Attitudinal Questions

I consider myself injured if I…. Style Injury Strongly Agree Mildly Mildly Disagree Strongly Status Agree agree disagree disagree n(%) n(%) n(%) n(%) n(%) n(%) … have any pain when I dance. Ballet Injured 3(3.0) 5(5.1) 17(17.2) 9(9.1) 43(43.4) 22(22.2) (N=99)

Not 0 1(1.3) 8(10.4) 10(13.0) 33(42.9) 25(32.5) injured (N=85)

Modern Injured 0 3(7.7) 7(17.9) 8(20.5) 14(35.9) 7(17.9) (N=39)

Not 0 2(4.7) 4(9.3) 5(11.6) 25(58.1) 7(16.3) injured (N=43)

… must modify movements when I Ballet Injured 13(13.3) 30(30.6) 36(36.7) 6(6.1) 12(12.2) 1(1.0) dance due to pain. (N=98)

Not 3(3.8) 27(34.6) 17(21.8) 16(20.5) 12(15.4) 2(2.6) injured (N=77)

Modern Injured 4(10.3) 11(28.2) 15(38.5) 8(20.5) 0 1(2.6) (N=39)

Not 3(7.0) 12(27.9) 10(23.3) 9(20.9) 9(20.9) 0 injured (N=43)

Table 3.38: Responses to Attitudinal Questions

I consider myself injured if I…. Style Injury Strongly Agree Mildly Mildly Disagree Strongly Status Agree agree disagree disagree n(%) n(%) n(%) n(%) n(%) n(%) …miss a company class or Ballet Injured 17(17.2) 28(28.3) 22(22.2) 10(10.1) 20(20.2) 2(2.0) rehearsal due to dance-related (N=99) pain. Not 12(15.6) 26(33.8) 15(19.5) 10(13.0) 10(13.0) 4(5.2) injured (N=77)

Modern Injured 6(15.4) 20(51.3) 10(25.6) 0 3(7.7) 0 (N=39)

Not 6(14.0) 20(46.5) 6(14.0) 3(7.0) 5(11.6) 3(7.0) injured (N=43)

…miss more than one day of work Ballet Injured 18(18.2) 40(40.4) 18(18.2) 10(10.1) 12(12.1) 1(1.0) due to dance-related pain. (N=99)

Not 11(14.3) 36(46.8) 12(15.6) 7(9.1) 10(13.0) 1(1.3) injured (N=77)

Modern Injured 13(33.3) 18(46.2) 6(15.4) 1(2.6) 1(2.6) 0 (N=39)

Not 11(25.6) 25(58.1) 2(4.7) 2(4.7) 3(7.0) 0 injured (N=43)

Table 3.38: Responses to Attitudinal Questions

I consider myself injured if I…. Style Injury Strongly Agree Mildly Mildly Disagree Strongly Status Agree agree disagree disagree n(%) n(%) n(%) n(%) n(%) n(%) … am unable to participate in a Ballet Injured 49(49.5) 42(42.4) 6(6.1) 1(1.0) 1(1.0) 0 performance due to dance-related (N=99) pain. Not 35(45.5) 33(42.9) 4(5.2) 2(2.6) 2(2.6) 1(1.3) injured (N=77)

Modern Injured 25(64.1) 12(30.8) 2(5.1) 0 0 0 (N=39)

Not 26(60.5) 14(32.6) 2(4.7) 0 1(2.3) 0 injured (N=43)

…must take medication due to my Ballet Injured 19(19.4) 24(24.5) 23(23.5) 14(14.3) 18(18.4) 0 dance-related pain. (N=98)

Not 11(14.3) 19(24.7) 19(24.7) 12(15.6) 13(16.9) 3(3.9) injured (N=77)

Modern Injured 13(33.3) 12(30.8) 8(20.5) 4(10.3) 2(5.1) 0 (N=39)

Not 14(32.6) 7(16.3) 13(30.2) 3(7.0) 6(14.0) 0 injured (N=43)

Table 3.38: Responses to Attitudinal Questions

I consider myself injured if I…. Style Injury Strongly Agree Mildly Mildly Disagree Strongly Status Agree agree disagree disagree n(%) n(%) n(%) n(%) n(%) n(%) …must seek care from a health- Ballet Injured 16(16.2) 17(17.2) 19(19.2) 16(16.2) 27(27.3) 4(4.0) care practitioner for my dance- (N=99) related pain. Not 10(13.0) 22(28.6) 10(13.0) 17(22.1) 14(18.2) 4(5.2) injured (N=77)

Modern Injured 3(7.7) 15(38.5) 12(30.8) 6(15.4) 3(7.7) 0 (N=39)

Not 2(4.7) 9(20.9) 12(27.9) 6(14.0) 11(25.6) 3(7.0) injured (N=43)

… must go to the hospital due to Ballet Injured 61(61.6) 29(29.3) 6(6.1) 3(3.0) 0 0 my dance-related pain. (N=99)

Not 42(54.5) 24(31.2) 8(10.4) 2(2.6) 1(1.3) 0 injured (N=77)

Modern Injured 24(61.5) 13(33.3) 2(5.1) 0 0 0 (N=39)

Not 23(53.5) 17(39.5) 2(4.7) 0 0 1(2.3) injured (N=43)

Table 3.38: Responses to Attitudinal Questions

I consider myself injured if I…. Style Injury Strongly Agree Mildly Mildly Disagree Strongly Status Agree agree disagree disagree n(%) n(%) n(%) n(%) n(%) n(%) … have visual signs such as Ballet Injured 26(26.5) 37(37.8) 21(21.4) 8(8.2) 6(6.1) 0 redness or swelling that (N=98) accompany my pain. Not 19(25.3) 32(42.7) 17(22.7) 3(4.0) 3(4.0) 1(1.3) injured (N=75)

Modern Injured 13(33.3) 13(33.3) 7(17.9) 2(5.1) 2(5.1) 2(5.1) (N=39)

Not 8(18.6) 13(30.2) 11(25.6) 7(16.3) 3(7.0) 1(2.3) injured (N=43)

79 80

3.16 Company Contextual Information Company contextual information for the 2007-2008 season is detailed in Table 3.39 for easy comparison. The participating ballet companies range in size from 67 to 83 dancers, whereas the modern dance companies are smaller ranging in size from 12 to 20 dancers. However, the number of performance and productions per season are not dependent on the size of the company. The Royal Danish Ballet had the highest number of performances overall with 153 total performances and 12 separate productions for the 2008 season. The Ensemble Batsheva had the second highest number with 120 performances for the season and eight productions. The Toronto Dance Theatre had the lowest number of performances with 30 for the season and four productions.

Daily company class is required in all companies with the exception of the Royal Danish Ballet and the National Ballet of Canada; however, dancers are still expected to attend the class. Onsite healthcare treatment is available at the workplace for all the ballet companies as well as the Kibbutz Contemporary Dance Companies. The Royal Danish Ballet was the only company to have “sick classes” specifically for injured dancers.

The number of weeks of vacation also varied greatly ranging from a low of three weeks for the National Ballet of Canada dancers to a high of 12 weeks for the Royal Danish Ballet and Toronto Dance Theatre dancers. The ballet dance company dancers all belong to unions as well as the Cullberg Ballet dancers. No other modern dance companies were unionized. The Royal Swedish Ballet is the only company to perform on a raked (sloped) stage in their home theatre. Studios for training and rehearsals are also raked at the Royal Swedish Ballet.

Table 3.39 : Company Contextual Data for the 2007-08 Season Dance Size of Performances/ Productions/ Daily Onsite Weeks Dancers “Sick Raked Company Company year year Company treatment vacation/year. Unionized? Classes” Stage? (# of Class available? for dancers) injured dancers Ballet:

NBC 69 85 4 Optional Yes 3 Yes No No

RSB 67 73 8 Required Yes 10 Yes No Yes

RDB 83 153 12 Optional Yes 12 Yes Yes No

Modern:

TDT 16 30 4 Required No 12 No No No

CUL 20 55 8 Required No 6 Yes No No

BAT 20 110 8 Required No 6 No No No

ENS 15 120 8 Required No 6 No No No

KDC 17 70 6 Required Yes 4 No No No

KDC2 12 100 4 Required Yes 4 No No No Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; KDC, Kibbutz Contemporary Dance Company; KDC2, Kibbutz Contemporary Dance Company 2

81 82

Chapter 4: Discussion

4.1 Principal Findings Prevalence of Injury Almost all of the dancers in this study reported some degree of current dance-related pain. This finding is consistent with the findings reported previously in the literature.4, 13 This is one of the largest cross-sectional studies of musculoskeletal injury in professional ballet and modern dancers. I have focused specifically on point prevalence in order to reduce recall bias. A study of Australian athletes found that only 61% were able to remember the number, body region and diagnoses of injuries sustained in the previous 12 months. 53

The point prevalence of dance-related musculoskeletal injury in dancers is high using two distinct outcomes for injury, and the estimate varies by case definition. The point prevalence of self-reported injury was higher than the point prevalence of SEFIP ≥3 injury in all companies with the exception of the Kibbutz Contemporary Dance Company and the Kibbutz Contemporary Dance Company 2. The prevalence estimates for these two companies must be interpreted with caution as these were the two companies that had the lowest response rates. It is possible that due to the difficult circumstances on the day of the survey, injured dancers left to deal with their injuries and did not participate. Self reported injury and SEFIP injury estimates may have been higher if that was indeed the case in this group. I have calculated the prevalence rates of self-reported injury with the assumption that all non-participants in the Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 would have considered themselves injured. Under this assumption, the prevalence (with 95% CI) of self- reported injury would increase from 9.1% to 41.1% (17.8 - 64.6) and from 37.5% to 58.3% (30.4 – 86.2) respectively. If these non-participants were to have reported SEFIP scores ≥3 as well, the Kibbutz Contemporary Dance Company prevalence of SEFIP ≥3 injury would increase from 54.5% to 70.6% (48.9 – 92.3) and the Kibbutz Contemporary Dance Company prevalence would remain at 100.0%. However, cultural attitudes towards pain and injury may also account for this difference given that the Kibbutz Contemporary Dance Companies had the highest overall percentage of dancers native to that country (Table 3.4). Cultural and racial differences in perception of pain and injury have been reported in various cultures.54

82 83 Injury Patterns Injury patterns differ between professional ballet and modern dancers. The injury patterns for self-reported injury in professional ballet dancers are consistent with previous findings in the literature.4 However, professional modern dancers do not have a distinct pattern with and the frequency of injury for specific body regions differs between modern companies. Although there are variations between specific schools of ballet, for the most part, ballet is a fairly uniform language of movement. Modern dance however originated as a rebellion against ballet and there are many different types of techniques or schools that vary widely from one another. This variation in repertoire and style of modern dance between the companies participating in this study likely explains the variation in the types of injuries that dancers in a particular modern dance company experienced. It is interesting to note that at the time the survey was performed, the Royal Danish Ballet was performing a mixed repertoire evening that included a modern dance piece by the choreographer of the Batsheva Dance Company, yet their injury patterns did not deviate significantly from those of other ballet companies.

Factors Associated with Injury This is the largest cross-sectional study of professional ballet and modern dancers to make use of a multivariable analysis to investigate factors independently associated with dance-related injury. It is important to note that these factors did vary with the two different case definitions used. Rank was independently associated with self reported injury in ballet dancers with soloists and principal dancers more likely to report injury than corps de ballet dancers. Ramel et al had a similar finding in professional Swedish ballet dancers.14 This may be explained by the more challenging roles that soloists and principal dancers perform. Additionally, the pressure to continue to dance even when injured may be greater for soloists and principal dancers if there is no understudy.

There was a trend for female ballet dancers to be less likely to be injured for the self-reported injury outcome, although the results were not statistically significant. This may be explained by the higher percentage of female ballet dancers with a SEFIP score of ≥3 that did not consider themselves injured (Table 3.41). Hamilton et al. found differences in personality traits between male and female ballet dancers.18 They report that male ballet dancers have more negative personality traits and psychological distress than female dancers or men in the general population. Female ballet dancers were reported to have been more adjusted than male ballet

84 dancers, as well as tough-minded, disciplined, and caring than the male ballet dancers.18 It is possible that these traits may play a role in their perception of injury. It is also possible that physiological differences in female body types may make them less susceptible to injury than male ballet dancers. For example, greater flexibility or bone and joint structure in females may make them more able to attain the typical ideal aesthetic requirements in ballet such as turn out at the hips. However, these physiological differences have not yet been shown to be associated with injury in dancers.

Number of years dancing professionally was independently associated with injury in ballet dancers for the SEFIP ≥3 outcome. The longer one is exposed to dancing at an elite professional level, the more likely one is to have functional difficulties due to the rigorous physical strain dancers put their bodies through.

For modern dancers, the only factor that was found to be associated with self-reported injury was company. The Kibbutz Contemporary Dance Company was less likely to report injury than dancers in the Toronto Dance Theatre. The reason for this association can be seen clearly from the prevalence estimates with the Kibbutz Contemporary Dancers reporting very low frequencies of self-reported injury as mentioned previously. This association was not found with the SEFIP≥3 outcome.

Injury Characteristics and Time-loss from Work The majority of injured ballet and modern dancers reported injuries of longer than three months duration. This suggests that the majority of injuries in both ballet and modern dancers are of a chronic nature. Additionally, between 21-28% of all injured dancers consider their injury severe in nature. However, there is a disconnect in certain instances between the injury severity rating and the amount of time that dancers are taking off work due to their injury. Very few modern dancers are taking any extended time off work due to their injuries. In fact, in the Cullberg Ballet, although 50% of injured dancers rated their injuries as severe, only one dancer took a week off of work while the remaining 87.5% of injured dancers reported taking no time off work due to their injury in the preceding year.

Scandinavian ballet dancers and dancers in the Batsheva Dance Company were more likely to take extended amounts of time off work due to their injuries. Societal support may help to

85 explain this ability to take time off work when injured. Scandinavian dancers have better overall job security and social support than dancers in Canada and Israel.3 Israel likely lies somewhere between Scandinavia and Canada regarding both social support for injured dancers as well as job security for injured dancers. However, this does not explain the reason why Cullberg Ballet dancers are not taking very much time off from work, as it is a Swedish dance company with the same social and health benefits for injured dancers as the Royal Swedish Ballet. A likely reason for this difference may lie in the make-up of the company members. The Cullberg Ballet had the lowest percentage of dancers from the country of the dance company with only 31.3% of their dancers of Swedish origin. Foreign dancers may either not understand the benefits they have, may have different cultural attitudes towards these social benefits, or may not yet have access to the full job security benefits if they have not been in the company for a minimum of three years. In this case, the median number of years in the present company for Cullberg Ballet dancers was 2.5 years compared to 7.5 years for dancers in the Royal Swedish Ballet.

The size of the company may also influence the ability of a dancer to take any extended time off work when injured. Although the Royal Danish Ballet has the highest number of performances per year (153), it also has the largest number of dancers (83). Therefore, they have the ability to substitute dancers in roles in each work. The Ensemble Batsheva performs 120 performances per year, yet has a much smaller number of dancers (15). This may significantly increase the number of performances per year that each individual dancer performs as well as the amount of rehearsal hours for each dancer. However, this may also increase the amount of pressure on the individual injured dancer to return to work quickly.

Healthcare and Pain Medication Use The majority of professional dancers overall are receiving treatment for their dance related pain and primarily from physiotherapists and massage therapists. Very few ballet dancers were receiving care from medical doctors and no modern dancers reported receiving care from medical doctors. The difference in health care use between these groups may be due to the availability of medical doctor (MD) care. All of the ballet companies had an MD on-site at least once a week whereas no modern dance company provided access to onsite medical doctor care. The lower use of medical doctor care compared to other types of healthcare may be also due in part to the nature of the injures if they are primarily chronic overuse type of injuries. Therefore, a medical doctor may refer the dancer for physiotherapy or rehabilitation and only continue to

86 follow those injuries which are acute in nature or may require surgery. Dancers may also have been referred for physiotherapy for previous injuries and due to the ease of access to physiotherapy care, choose to first attempt care with a physiotherapist.

A large percentage of dancers are using pain medication for their dance-related pain. This figure was especially high in Canadian dancers with over 50% using pain medication for dance-related pain at the time of data collection. The reason for higher use of pain medications in Canadians is unclear however this may possibly be due to cultural differences.

Injury Reporting More than 15% of injured ballet and modern dancers did not report their injuries. Two of the four most cited reasons for not reporting an injury (“Pain is an inherent part of dancing” and “I can cope with the pain”) may indicate that dancers believe pain is part and parcel of their working lives. The reason “I did not want to stop dancing” may be a red flag, however, for the pressure that dancers feel to continue to dance despite being in significant pain and considering themselves injured. Additional reported reasons that may point to a psychosocial component for not reporting injury include: “I did not want to be seen as unreliable”, “I did not want to negatively affect the production”, “I did not want to lose a role”, and “I did not want to let my company down”. Of those dancers who did report their injuries, most did so to either the rehearsal directors or company health professionals (in those companies that had a company health professional).

Of additional interest is the fact that 50% of injured Danish dancers had reported their injuries to the local worker’s compensation board followed by 30% in the Royal Swedish Ballet and the Batsheva Dance Company. No Canadian dancers had injuries reported to the worker’s compensation board. The National Ballet of Canada dancers are not eligible for workers’ compensation because they are primarily contract workers. However, no dancers from the Toronto Dance Theatre had reported an injury that was reported to the workers’ compensation board as well.

Attitudes Towards Injury This is also one of the first studies to explore professional dancers’ attitudes towards injury. Pain alone is not an indicator of injury for professional dancers. For the most part, dancers agreed they

87 would consider themselves injured if they could not perform or had to go to hospital due to dance-related pain with only a few dancers disagreeing with these statements. The majority of dancers also agreed they would consider themselves injured if they had visual signs such as redness and swelling accompanying their pain, had to seek healthcare, or had to take medications due to their pain. However, many dancers disagreed with these statements. Additionally, attitudes regarding time-loss from work and functional changes besides not being able to perform were varied. Most dancers agreed they would consider themselves injured if they missed more than one day of work, missed company class or rehearsal, or had to modify their movements due to pain, but many dancers also disagreed with these statements.

4.2 Implications of Principal Findings The difference in prevalence estimates for two different injury outcomes points to the importance of case definition in dance injury and surveillance research. Future prospective as well as cross- sectional studies should use clear definitions of injury. Due to the variations in attitudes and perceptions towards injury seen in this population of dancers, I suggest incorporating a broad definition of injury in order to capture as many injured dancers as possible. These injuries can then be subdivided as Bronner et al. have suggested if the dancer has lost time from work, sought healthcare for their injury, has financial loss from their injury, or has only a physical complaint.36 Functional impairment alone may be problematic as a definition to capture and study injured dancers as many dancers are continuing to dance with pain and may potentially be injured. As a significant number of dancers do not consider themselves injured even when modifying movement due to pain, they may resist reporting themselves as injured. Additionally, time-loss from work alone should not be used as a definition to capture and study injured dancers as the results suggest that some injured dancers may not be losing any time from work.

The prevalence of dance-related pain and injury is very high regardless of the definition and the long-term consequences of this are unknown. Additionally, injured dancers are reporting very long injury durations, many beyond six months, suggesting chronic injury. Therefore, there is an urgent need to investigate interventions to help control injury and understand the long-term implications of these conditions. There is preliminary evidence that comprehensive injury management and prevention programs for both professional ballet and modern dancers may decrease injury incidence as well as economic costs associated with injury.25, 27, 28 However these studies are uncontrolled observational designs and therefore the conclusions are limited.

Since injury patterns vary between professional modern dance companies, a tool such as the SEFIP may be useful for seasonal planning. Modern dance companies will often have visiting choreographers as well as repertoire that varies from season to season. Using a tool such as the SEFIP can help to identify which body areas are more likely to be injured during a certain production. If that production is repeated later in the season or in a subsequent season, these injury types can then be anticipated. This could be useful in planning repertoire or identifying and modifying choreography to help minimize injury. Ramel suggested that dancers with a SEFIP score of 2 or more be examined by a dance science professional.40 The SEFIP could be

89 useful for the dance company health professionals to assist in identifying dancers that continue to work with functional issues (SEFIP score ≥3) yet are reluctant to consider themselves injured as may have been the case in this study with the dancers in the Kibbutz Contemporary Dance Companies. These dancers might be targeted for increased confidential surveillance and treatment of their injuries.

This study suggests that rank is independently associated with injury in ballet dancers. Dance health professionals should aim to identify the special needs of these dancers in their injury prevention and rehabilitation programs. The number of years dancing professionally was also found to be independently associated with a SEFIP score ≥3 in ballet dancers. Efforts should be made to support older and more experienced dancers deal with their injuries. As injury may possibly lead to the end of a career for a dancer, this support should include physical as well as psychological components. These findings need to be confirmed in a prospective study design to determine if the associated factors are indeed risk factors for injury.

It is clear that the high prevalence of reported injury, lengthy reported injury durations, and in some cases extended time off work due to these injuries, places a high burden on the dance companies themselves to deal with their injured workers. The discrepancy however between the higher percentages of ballet dancers taking extended time off from work due to their injuries compared to modern dancers is concerning. This discrepancy is also seen between the amount of time that ballet dancers in the Scandinavian countries were off work due to their injuries compared to ballet dancers in Canada. This suggests that company or country level factors may play a role in the ability of a dancer to take the appropriate time off to recover from an injury. This may in turn have an effect on future injury or potentially a shortened career. The difference in access to benefits and frequency of reporting of injuries as work injuries between the countries supports this need for further exploration of these societal and company level factors. Although the social benefits in Scandinavian countries are vastly different than in Canada or Israel, all dance companies should strive to provide their dancers with job security and the ability to take the appropriate time off work to recover from injuries as recommended by healthcare professionals. This responsibility does not lie however with the dance company alone. Government support for dance and the arts in general is higher in Scandinavian countries than in Israel or Canada. Governments should be aware of the high burden of pain and injury in professional dancers and strive to increase the needed support to these populations.

Larger studies are needed to investigate these higher level company and country factors with multi-level modeling. This will help to determine if factors such as number of performances, productions, availability of social or medical support or other company or country level factors are associated with injury. In the meantime however, smaller companies with high numbers of performances and productions should be aware that their dancers may have an increased dance exposure compared to dancers in larger companies or companies with smaller number of performances or productions. Efforts to decrease this exposure and potentially decrease injury in these dancers should include increasing the number of dancers in the company and/or decreasing the number of performances per season. Exposure to dance is more easily measured in a prospective study, and a better measure of exposure involves time at risk. Ideally, time-based exposure should be evaluated by determining number of injuries per 1000 hours of dance- participation as has been adopted by many European sports injury researchers.36

Two subsets of dancers have been identified that are of special concern. These are dancers who are not reporting their injuries and dancers who are dancing through pain and functional issues potentially as a result of their attitudes towards injury. The fact that more than 15% of all injured professional dancers have not reported their injuries is very important as this affects all measures of injury prevalence and incidence. Future studies of musculoskeletal injury in dancers should keep this in mind when deciding how best to capture injured dancers. Dance injury registries should make efforts to use those individuals that dancers are most likely to report their injuries to, such as rehearsal directors and company health professionals. Rehearsal directors often have the most work contact with dancers and therefore a high level of trust may be developed. Dancers may also be very trusting of company health professionals due to the guarantee of confidentiality. Of the reasons given for not reporting an injury, “I did not want to stop dancing” especially deserves further attention. This may point towards a fear of dealing with or accepting the possibility of injury and possibly losing time from work. This may cause a dancer to continue to dance with pain and possibly ignore warning signs of injury. Additional reasons reported point towards psychosocial pressures within the company. It is clear that there is a need for professional dance companies to develop measures that allow dancers, who are in pain and may be injured, to feel comfortable and secure enough to report their injuries.

91 The attitudinal results suggest that there is a subset of dancers who have attitudes towards injury that may cause them to continue to dance with pain and functional impairment. It is possible that the experience of injury may lead a dancer to better understand injury and this may have an impact on their perception of considering themselves injured or not injured. Although many dancers who are modifying movement due to pain may consider themselves injured, the preliminary findings of dancers’ attitudes towards injury, as well as the fact that 19.8% of dancers who did not consider themselves injured had a SEFIP score of 3, bring light to the fact that many dancers are dancing with pain as well as functional impairment without considering themselves injured. There is some suggestion in the literature that these behaviors may lead to chronic injury, although this has yet to be proven.14, 20 However, the high prevalence of reported chronic injury in this group of professional dancers lends support to this theory. Education regarding pain and injury is essential for these two subsets of dancers so they may be better able to recognize when they are injured and seek the appropriate care. Qualitative research is needed to better understand dancers’ attitudes and perceptions of pain and injury.

There is also some suggestion from the findings of this study that dancers may be using pain medications (prescription and non-prescription) in order to continue to dance with pain which may also have an impact on one’s attitudes towards pain and injury. This is especially worrisome given the low prevalence of dancers under medical care for their dance-related pain. Studies of elite Olympic athletes have demonstrated a dangerous overuse of non-steroidal anti- inflammatory drugs (NSAIDs) as well as inappropriate use of concurrent multiple types of NSAIDs and other medications.55 Gastrointestinal and central nervous system adverse effects associated with NSAID use have been commonly reported in elite athletes.56 Additionally, there is evidence from animal studies that the long term use of NSAIDs may actually inhibit protein synthesis and therefore delay tissue healing.56 Further studies of pain medication use in professional dancers are warranted, especially in Canada. Educational measures are urgently needed for dancers regarding the appropriate use of pain medications and potential adverse reactions.

4.3 Strengths and Limitations This is the largest cross-sectional study of solely professional ballet and modern dancers to date and one of the first international studies of professional dancers. I have focused on the point

92 prevalence of injury in these dancers in order to reduce recall bias. Additionally, I used multivariable analysis to measure associated factors which has rarely been used in studies of professional dancers. The response rate in this study was very good overall and I used a comprehensive and psychometrically sound inventory of questions.

Care should be taken in interpreting factors associated with injury. As this is a cross-sectional study, these should not be interpreted as risk factors. Confirmatory prospective studies should be undertaken to ascertain if any of the associated factors are indeed risk factors for injury. In addition, the odds ratios I report likely overestimate the reported associations since the outcomes used in my models are not rare events.

Although, the results of this study are limited to the participating dance companies, they may be generalizable to professional dancers in similar elite ballet companies. Caution should be taken when attempting to generalize the results to dancers in other modern dance companies as it is clear that modern dance companies are more heterogeneous than ballet companies. Caution should also be taken when attempting to generalize to companies that do not operate on a full- time basis (project based companies) or to freelance dancers. Although this is one of the largest studies of professional dancers to date, modern dance companies are usually quite small in size and this led to a lower number of modern dancers compared to ballet dancers in this study. Small sample size may account for the difficulty in multivariable analysis in modern dancers. I strived to obtain at least one modern and ballet company in each of the countries however the number of larger modern companies in each country is limited and I was therefore unable to recruit a modern dance company in Denmark. Additionally, I was unable to include a ballet company in Israel.

Additionally, my sample was too small to attain sufficient power to perform multi-level modeling to compare higher order factors such as country (societal) and dance company factors. I was unable, therefore, to fully analyze company and country level data to determine its association with injury in dancers. In addition to company and country level contextual data, it is possible that other factors that I did not measure such as psychosocial/psychological factors may play a role in injury in dancers. These factors have recently been explored in studies of Korean dancers and should be studied in future studies of professional dancers in other countries. 31, 34

93 Following the instructions of the research ethics board, I could not contact or identify those dancers who did not participate; therefore I do not have any information regarding these dancers. It is possible that these dancers may have been injured. However, every attempt was made to capture all dancers who were off work on the date of the survey distribution. These dancers were mailed surveys in order to minimize any “healthy worker effect” in the results of this study. If indeed a “healthy worker effect” came into play in this study, then the reported prevalence estimates would be lower than the true estimate. This may have been the case with the lower participation rate in the Kibbutz Contemporary Dance Companies and I have reported alternate prevalence rates with the assumption that dancers who did not participate were injured. The true estimates are likely somewhere between these two estimates.

It must also be stressed that in self-reported survey based cross-sectional studies, the potential for misclassification of injury does exist. The self-reported injury outcome is injury from the dancer’s perspective. The dancer was not given a specific definition of injury and no specific diagnoses were made by health professionals. I have reported an alternate injury outcome, using the SEFIP. Although this has been validated for use in dancers, no tool is perfect, and it is indeed possible that misclassification of injury occurred using this outcome measure as well.

4.4 Future Directions Due to the high prevalence of dance-related injury, further research is essential to investigate possible interventions to help control injury and understand the long-term implications of injury in professional dancers. Large prospective studies are needed to clearly identify risk factors that are associated with injury in dancers. The use of an injury registry would allow researchers to measure dance exposure and risk factors for injury providing important information for professional dance companies. The associated factors identified in this study are only one piece of the dance injury puzzle. Further research should focus on societal and company level factors making use of multi-level modeling. Additionally, psychological and psychosocial factors and their relationship with injury should be investigated in this population. Qualitative studies may be used to further investigate dancers’ attitudes and perceptions of injury, identify barriers to reporting injuries, and how best to make dancers feel less vulnerable when reporting their injuries. Research into pain medication use in professional dancers and possible adverse effects is warranted given the high prevalence of dancers using these medications.

Chapter 5: Conclusions The prevalence of musculoskeletal pain and injury in professional ballet and modern dancers is high. Professional ballet dancers suffer mostly from injuries to the lower limb and low back. The types of injuries professional modern dancers suffer from vary among companies. The majority of reported injuries are chronic in nature in both ballet and modern dancers. The results suggest that modern dancers are less likely or able to take time off work due to injury. Soloist and principal ballet dancers are more likely to be injured than corps de ballet dancers for self- reported injury. Additionally, the number of years dancing professionally was positively associated with injury in ballet dancers using a SEFIP score of ≥3 as the outcome.

The attitudes and perceptions towards injury vary in this population. Some dancers are continuing to dance with pain and injury possibly as a result of these attitudes or fears of having to stop dancing. This may potentially put these dancers at risk for further or greater injury. Additionally, more than 15% of injured professional dancers are not reporting their injuries for a variety of reasons including not wanting to have to stop dancing. Measures to support this subset of injured professional dancers are necessary. Professional ballet and modern dancers are using high levels of pain medications especially in Canada. Further research into dancers’ pain medication use is essential. Large scale prospective studies are recommended to further investigate risk factors for injury in professional dancers. Additionally qualitative studies are recommended to further investigate dancers’ attitudes and perceptions of injury and how best to support dancers afraid to report injury. Most importantly, there is an urgent need to investigate interventions to help control injury and understand the long-term implications of these conditions in this population.

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99 43. Cummings SR, Stewart AL, Hulley SB. Designing questionnaires and data collection instruments. In: Hulley SB, Cummings SR, Browner WS, Grady DG, Hearst N, Newman TB, editors. Designing Clinical Research. Second ed. Philidelphia: Lippincott Williams & Wilkins; 2001. p. 231-45. 44. Canadian guidelines for bodyweight classification in adults [homepage on the Internet]. Canada: Health Canada. c2005 August 10, 2005 [cited January 30, 2010]. Available from: http://www.hc-sc.gc.ca/fn-an/nutrition/weights-poids/guide-ld-adult/qa-qr-pub-eng.php. 45. Low income cut-offs for 2006 and low income measures for 2005 [homepage on the Internet]. Ottawa, Ontario: Statistics Canada. c2007 May, 2007 [cited December 3, 2007]. Available from: http://www.statcan.gc.ca/pub/75f0002m/75f0002m2007004-eng.pdf. 46. Children and their families 2008:Large economic differences among families with children [homepage on the Internet]. Stockholm, Sweden: Statistics Sweden. c2008 November 23, 2009 [cited January 30, 2010]. Available from: http://www.pubkat.scb.se/Pages/PressArchive____259760.aspx?PressReleaseID=282507. 47. Hartvigsen J. Communication with Statistics Denmark. 2009 March 26, 2009. 48. Schwartz I. Israeli low income cut-offs. January 26, 2008 (personal communication). 49. Jensen MP, Karoly P, Braver S. The measurement of clinical pain intensity; A comparison of six methods. Pain. 1986;27(1):117-126. 50. Fejer R, Jordan A, Hartvigsen J. Categorizing the severity of neck pain: Establishment of cut- points for use in clinical and epidemiological research. Pain. 2005;119(1):176-182. 51. Peng, C.J. and So, T.H. Logistic regression analysis and reporting: A primer. Understanding Statistics. 2002;1(1):31-70. 52. Bewick V, Cheek L, Ball J. Statistics review 14: Logistic regression. Crit Care. 2005;9(1):112-118. 53. Gabbe BJ, Finch CF, Bennell KL, Wajswelner H. How valid is a self reported 12 month sports injury history? Br J Sports Med. 2003;37(6):545-7. 54. Edwards CL, Fillingim RB, Keefe F. Race, ethnicity and pain. Pain. 2001 November, 2001;94(2):133-7. 55. Corrigan B, Kazlauzkas R. Medication use in athletes selected for doping control at the Sydney Olympics (2000). Clin J Sport Med. 2003;13(1):33-40. 56. Alaranta A, Alaranta H, Helenius I. Use of prescription drugs in athletes. Sports Med. 2008;38(6):449-463.

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Appendix 1: Electronic Database Search Strategies

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Appendix 3 : Research Ethics Board Approvals

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Professor Jan Hartvigsen Institut for Idræt og Biomekanik Syddansk Universitet Campusvej 55 5230 Odense M

Sendt til: [email protected]

5. november 2007 Vedrørende anmeldelse af: Perception of Musculoskeletal Injury in Professional Dancers Datatilsynet Borgergade 28, 5. 1300 København K

CVR-nr. 11-88-37-29 Ovennævnte projekt er den 23. august 2007 anmeldt til Datatilsynet efter persondatalovens1 § 48, stk. 1. Der er samtidigt søgt om Datatilsynets Telefon 3319 3200 tilladelse. Fax 3319 3218

E-post Det fremgår af anmeldelsen, at De er dataansvarlig for projektets oplysninger. [email protected] Behandlingen af oplysningerne ønskes påbegyndt snarest og forventes at www.datatilsynet.dk ophøre 31. januar 2010.

J.nr. 2007-41-0979 Oplysningerne vil blive behandlet på følgende adresse: Institut for Idræt og Biomekanik, Syddansk Universitet, Campusvej 55, 5230 Odense M. Sagsbehandler Maiken Toftgaard Knudsen Oplysningerne vil endvidere blive behandlet ved det deltagende center: Direkte 3319 3248 Toronto Western Hospital, 399 Bathurst Street, Felle Pavilion 4-114, Toronto, Ontario, Canada M5T 2S8.

TILLADELSE

Datatilsynet meddeler hermed tilladelse til projektets gennemførelse, jf. persondatalovens § 50, stk. 1, nr. 1. Datatilsynet fastsætter i den forbindelse nedenstående vilkår:

Generelle vilkår

1 Lov nr. 429 af 31. maj 2000 om behandling af personoplysninger med senere ændringer.

124 Tilladelsen gælder indtil: 31. januar 2010

Ved tilladelsens udløb skal De særligt være opmærksom på følgende:

Hvis De ikke inden denne dato har fået tilladelsen forlænget, går Datatilsynet ud fra, at projektet er afsluttet, og at personoplysningerne er slettet, anonymiseret, tilintetgjort eller overført til arkiv, jf. nedenstående vilkår vedrørende projektets afslutning. Anmeldelsen af Deres projekt fjernes derfor fra fortegnelsen over anmeldte behandlinger på Datatilsynets hjemmeside.

Datatilsynet gør samtidig opmærksom på, at al behandling (herunder også opbevaring) af personoplysninger efter tilladelsens udløb er en overtrædelse af persondataloven, jf. § 70.

1. Professor Jan Hartvigsen er ansvarlig for overholdelsen af de fastsatte vilkår.

2. Oplysningerne må kun anvendes til brug for projektets gennemførelse.

3. Behandling af personoplysninger må kun foretages af den dataansvarlige eller på foranledning af den dataansvarlige og på dennes ansvar.

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7. Behandling af oplysninger skal tilrettelægges således, at oplysningerne ikke hændeligt eller ulovligt tilintetgøres, fortabes eller forringes. Der skal endvidere foretages den fornødne kontrol for at sikre, at der ikke behandles urigtige eller vildledende oplysninger. Urigtige eller vildledende oplysninger eller oplysninger, som er behandlet i strid med loven eller disse vilkår, skal berigtiges eller slettes.

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9. En eventuel offentliggørelse af undersøgelsens resultater må ikke ske på en sådan måde, at det er muligt at identificere enkeltpersoner.

10. Eventuelle vilkår, der fastsættes efter anden lovgivning, forudsættes overholdt.

Elektroniske oplysninger

11. Identifikationsoplysninger skal krypteres eller erstattes af et kodenummer el. lign. Alternativt kan alle oplysninger lagres krypteret. Krypteringsnøgle, kodenøgle m.v. skal opbevares forsvarligt og adskilt fra personoplysningerne.

125 12. Adgangen til projektdata må kun finde sted ved benyttelse af et fortroligt password. Password skal udskiftes mindst én gang om året, og når forholdene tilsiger det.

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Manuelle oplysninger

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Oplysningspligt over for den registrerede

16. Hvis der skal indsamles oplysninger hos den registrerede (ved interview, spørgeskema, klinisk eller paraklinisk undersøgelse, behandling, observation m.v.) skal der uddeles/fremsendes nærmere information om projektet. Den registrerede skal heri oplyses om den dataansvarliges navn, formålet med projektet, at det er frivilligt at deltage, og at et samtykke til deltagelse til enhver tid kan trækkes tilbage. Hvis oplysningerne skal videregives til brug i anden videnskabelig eller statistisk sammenhæng, skal der også oplyses om formålet med videregivelsen samt modtagerens identitet.

17. Den registrerede bør endvidere oplyses om, at projektet er anmeldt til Datatilsynet efter persondataloven, samt at Datatilsynet har fastsat nærmere vilkår for projektet til beskyttelse af den registreredes privatliv.

Indsigtsret

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Videregivelse

19. Videregivelse af personhenførbare oplysninger til tredjepart må kun ske til brug i andet statistisk eller videnskabeligt øjemed.

20. Videregivelse må kun ske efter forudgående tilladelse fra Datatilsynet. Datatilsynet kan stille nærmere vilkår for videregivelsen samt for modtagerens behandling af oplysningerne.

Ændringer i projektet

21. Væsentlige ændringer i projektet skal anmeldes til Datatilsynet (som ændring af eksisterende anmeldelse). Ændringer af mindre væsentlig betydning kan meddeles Datatilsynet.

126

22. Ændring af tidspunktet for projektets afslutning skal altid anmeldes.

Ved projektets afslutning

23. Senest ved projektets afslutning skal oplysningerne slettes, anonymiseres eller tilintetgøres, således at det efterfølgende ikke er muligt at identificere enkeltpersoner, der indgår i undersøgelsen.

24. Alternativt kan oplysningerne overføres til videre opbevaring i Statens Arkiver (herunder Dansk Dataarkiv) efter arkivlovens regler.

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Overførsel af oplysninger til tredjelande

26. Overførsel af oplysninger til tredjelande, herunder til behandling hos databehandler samt til intern anvendelse i projektet, kræver forudgående tilladelse fra Datatilsynet.

27. Overførsel kan dog ske uden tilladelse, hvis den registrerede har givet udtrykkeligt samtykke til dette. Den registrerede kan tilbagekalde samtykket.

28. Overførsel af oplysninger skal ske med bud eller anbefalet post. Ved elektronisk overførsel skal der træffes de fornødne sikkerhedsforanstaltninger mod, at oplysningerne kommer til uvedkommendes kendskab. Oplysningerne skal som minimum være forsvarligt krypteret under hele transmissionen.

Ovenstående vilkår er gældende indtil videre. Datatilsynet forbeholder sig ret til senere at tage vilkårene op til revision, hvis der skulle vise sig behov for det.

Opmærksomheden henledes specielt på, at Datatilsynets vilkår også skal iagttages ved behandling af oplysninger på de deltagende centre mv., jf. de generelle vilkår nr. 4.

Datatilsynet gør opmærksom på, at denne tilladelse alene er en tilladelse til at behandle personoplysninger i forbindelse med projektets gennemførelse. Tilladelsen indebærer således ikke en forpligtelse for myndigheder, virksomheder m.v. til at udlevere eventuelle oplysninger til Dem til brug for projektet.

En videregivelse af oplysninger fra statistiske registre, videnskabelige projekter m.v. kræver dog, at den dataansvarlige har indhentet særlig tilladelse hertil fra Datatilsynet, jf. persondatalovens § 10, stk. 3.

Anmeldelsen offentliggøres i fortegnelsen over anmeldte behandlinger på Datatilsynets hjemmeside www.datatilsynet.dk.

Persondataloven kan læses/hentes på Datatilsynets hjemmeside under punktet "Lovgivning".

127 Med venlig hilsen

Maiken Toftgaard Knudsen

128

129

130 Appendix 4: Copyright Acknowledgements

The use of the Self-Estimated Functional Inability because of Pain (SEFIP) is with permission of Dr. Eva Ramel.