Childhood Obesity Prevention in China: a Mixed-Methods Approach to Inform Development of Theoretically Based Interventions
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CHILDHOOD OBESITY PREVENTION IN CHINA: A MIXED-METHODS APPROACH TO INFORM DEVELOPMENT OF THEORETICALLY BASED INTERVENTIONS By BAI LI A thesis submitted to the University of Birmingham for the degree of DOCTOR OF PHILOSOPHY Unit of Public Health, Epidemiology and Biostatistics School of Health and Population Sciences College of Medical and Dental Sciences University of Birmingham November 2012 1 University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. ABSTRACT Background Childhood obesity is increasing rapidly in China. However, research into environmental contributors to the problem is limited. Formative research that informs theoretically based prevention interventions is also lacking. Aim and objectives To inform the development of obesity prevention interventions among urban Chinese primary school students by: 1. exploring perceived factors contributing to obesogenic behaviours, 2. exploring preferred components and delivery strategies for future preventive interventions, 3. examining the relationship of family and neighbourhood environmental factors, to child weight status as well as related dietary and physical activity behaviours. Methods A mixed-methods study was conducted in two cities in South China. Seventeen focus groups and four personal interviews were conducted with family and primary school members from four socioeconomically distinct districts (objectives 1-2). In each district, height and weight data of 3rd year students (8-10 years) in one primary school was obtained, and linked to data obtained from a questionnaire sent to their parents that enquired about family and neighbourhood environments, as well as child behaviours (objective 3). Data from both studies were combined to inform the development of an 2 appropriate prevention intervention. Results Inter-related social, historical, regulatory, policy, knowledge and economic factors emerged as factors influencing attitudes, social norms and perceptions of control in relation to obesogenic behaviours. Among those, grandparents emerged as a dominant but relatively easy- to- modify theme. Overall, dietary interventions, particularly delivered through or at schools were most popular for future interventions. In parallel, the cross-sectional study (n=497) found that the presence and role of grandparents were significantly correlated with child weight status and snacking behaviour. No relationship was found between the perceived neighbourhood environment and child weight status or behaviours. Conclusions The family environment has important influences on childhood obesity and obesegenic behaviours. Drawing on the overall findings, potential targets, components and delivery strategies are discussed using a Social Marketing framework for future prevention intervention. 3 Dedicated to my mother and father For your generous support in my study in the UK for over 10 years & To my husband For your endless support and love 4 ACKNOWLEDGEMENTS I would like to first of all express my sincere gratitude to my supervisor, Dr Peymane Adab for her generous guidance and support in my PhD studies and in my development to be a more mature researcher. I would have been unable to complete this thesis without her support. I also would like to thank my supervisor, Professor KK Cheng for his support, particularly at the start of my PhD study. Both supervisors’ valuable advice and encouragement will stay with me for the rest of my life. I would like to thank the staff at the Unit of School Health and Hygiene (Guangzhou Education Bureau) and Hechi City Government for their support in the study’s data collection in China. My sincere thanks also go to all the participants (e.g. children, family members and school staff) in Guangzhou and Hechi cities, for their time and cooperation. I would like to acknowledge the contribution of University of Birmingham Medical and Dental Sciences College PhD Studentship, which made my research study possible. I have also received excellent peer support during 5 my study, especially in statistical analysis, from Dr Hubert Lam and Dr Karla Hemming. Outside the University, I would like to thank Professor Nadine Henley (in Social Marketing) for being a very inspirational friend who has given me invaluable encouragement. I can not express enough gratitude to my parents Professor Jin Bai and Professor Haisheng Li, who have been giving everything they can to enable me to fulfil my own pursuits in study, career and life. Their incredible love, understanding and support made important contributions to who I am today. To them, their only child studying abroad, thousands of miles away for over 10 years, meant far more than their very generous financial sacrifices. Finally, I thank my wonderful husband, Stephen John Ashdown for his endless love and encouragement, and thank my parents in law Valerie and John Ashdown for making up a warm and supportive family in the UK. I could not have done it without any of you. 6 CONTENTS 1 INTRODUCTION ........................................................................................................................... 15 1.1 RATIONALE FOR THIS THESIS 15 1.2 AN OVERVIEW OF THE THESIS 16 2 LITERATURE REVIEW ................................................................................................................ 18 2.1 CHILDHOOD OBESITY EPIDEMIC - AN INTERNATIONAL PERSPECTIVE 18 2.1.1 A global challenge 18 2.1.2 Defining obesity 20 2.1.2.1 Body Mass Index 21 2.1.2.1.1 Measuring BMI in children 22 2.1.2.2 Alternative measures used in epidemiological studies 24 2.1.3 Consequences of childhood obesity 25 2.1.4 Aetiology of childhood obesity 29 2.1.4.1 Genetic and biological determinants 30 2.1.4.2 Children’s health behaviour 31 2.1.4.3 Family environment 33 2.1.4.4 Neighbourhood environment 36 2.1.4.5 The wider environment 37 2.1.4.6 Sociodemographic Influences 39 2.1.4.7 Summary 39 2.1.5 Prevention of childhood obesity 40 2.2 EPIDEMIOLOGY AND RESEARCH ON CHILDHOOD OBESITY IN CHINA 44 2.2.1 Defining childhood obesity - the Chinese national standard 44 2.2.2 The prevalence of childhood obesity in China 45 2.2.2.1 Trend in childhood obesity 45 2.2.2.2 Descriptive epidemiology of childhood obesity in China 46 2.2.3 Chinese literature on the aetiology of childhood obesity 48 2.2.3.1 Genetic and biological risk factors 49 7 2.2.3.2 Behavioural risk factors- dietary behaviours 49 2.2.3.3 Behavioural risk factors - physical activity and sedentary behaviours 51 2.2.3.4 Sleep duration 52 2.2.3.5 Research gaps 52 2.2.4 Childhood obesity prevention research in China 54 2.2.4.1 Current literature and evidence base 54 2.2.4.2 Research gaps 57 2.2.5 Summary 65 2.3 THE OVERALL AIM OF THE RESEARCH PROJECT 66 3 UNDERSTANDING FACTORS INFLUENCING CHILDHOOD OBESITY IN CHINA AND INSIGHTS INTO INTERVENTION DEVELOPMENT .................................................................. 68 3.1 BACKGROUND 68 3.2 RESEARCH AIM AND OBJECTIVES 73 3.3 RESEARCH SETTING 74 3.4 METHODS 80 3.4.1 Participants 80 3.4.2 Focus group process 81 3.4.3 Personal interview process 85 3.4.4 Data trustworthiness for focus groups and interviews 86 3.4.5 Other observational activities 87 3.4.6 Data analysis 88 3.5 RESULTS 92 3.5.1 Factors perceived to influence obesity and related behaviours (objective 1) 93 3.5.1.1 Theme 1: factors influencing attitudes toward healthy behaviours 94 3.5.1.2 Theme 2: factors contributing to low perceived behavioural control 97 3.5.1.3 Theme 3: factors influencing more than one construct of the TPB 106 3.5.1.4 Summary 119 3.5.2 Findings from stakeholder prioritisation exercise (objectives 2-3) 122 3.5.2.1 Interventions prioritised across all focus groups 126 3.5.2.2 Non-prioritised interventions 127 8 3.5.2.3 Intervention prioritisation by stakeholder identity group 128 3.5.2.4 Cross - group variations in perceived importance and feasibility for prioritised interventions 131 3.5.2.5 Summary 133 3.5.3 Strategies for intervention delivery and insights into barriers and facilitators (objective 4) 134 3.5.3.1 Findings by identity groups 134 3.5.3.2 Summary 147 3.6 DISCUSSION 149 3.6.1 Summary of key findings 149 3.6.2 Strengths and limitations 151 3.6.3 Findings in relation to previous literature 154 3.6.3.1 Perceived factors contributing to childhood obesity and obesogenic behaviours 154 3.6.3.2 Preference for the components and delivery strategies of preventive interventions 159 3.7 CONCLUSION 162 4 CROSS-SECTIONAL STUDY TO IDENTIFY FAMILY AND NEIGHBOURHOOD ENVIRONMENTAL FACTORS ASSOCIATED WITH CHILDHOOD OBESITY AND OBESOGENIC BEHAVIOURS ....................................................................................................... 164 4.1 BACKGROUND 164 4.2 RESEARCH AIM AND OBJECTIVES 166 4.3 METHODS 167 4.3.1 Research setting 167 4.3.2 Study sample 168 4.3.3 Measures 169 4.3.3.1 Anthropometric measures (outcome) 169 4.3.3.2 Parent questionnaire 170 4.4 STATISTICAL ANALYSIS 177 4.5 RESULTS 181 4.5.1 Summary of the study sample 181 4.5.1.1 Characteristics of the study sample 182 4.5.1.2 Prevalence