Mechanisms of Motivational Interviewing in Weight Loss Maintenance
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Understanding the Therapeutic Process: Mechanisms of Motivational Interviewing in Weight Loss Maintenance Lauren Copeland Thesis submitted for the degree of Doctor of Philosophy Cardiff University Submitted January 2015 Supervisors Dr Sharon Simpson Dr Rachel McNamara Dr Mark Kelson Professor Stephen Rollnick Form: PGR_Submission_2012_01 NOTICE OF SUBMISSION OF THESIS FORM: POSTGRADUATE RESEARCH APPENDIX 1: Specimen layout for Thesis Summary and Declaration/Statements page to be included in a Thesis DECLARATION This work has not been submitted in substance for any other degree or award at this or any other university or place of learning, nor is being submitted concurrently in candidature for any degree or other award. Signed ………………………………………… (candidate) Date ………………………… STATEMENT 1 This thesis is being submitted in partial fulfillment of the requirements for the degree of …………………………(insert MCh, MD, MPhil, Thesis etc, as appropriate) Signed ………………………………………… (candidate) Date ………………………… STATEMENT 2 This thesis is the result of my own independent work/investigation, except where otherwise stated. Other sources are acknowledged by explicit references. The views expressed are my own. Signed ………………………………………… (candidate) Date ………………………… STATEMENT 3 I hereby give consent for my thesis, if accepted, to be available online in the University’s Open Access repository and for inter-library loan, and for the title and summary to be made available to outside organisations. Signed ………………………………………… (candidate) Date ………………………… STATEMENT 4: PREVIOUSLY APPROVED BAR ON ACCESS I hereby give consent for my thesis, if accepted, to be available online in the University’s Open Access repository and for inter-library loans after expiry of a bar on access previously approved by the Academic Standards & Quality Committee. Signed ………………………………………… (candidate) Date………………………… Acknowledgements Thank you to my supervisors Sharon Simpson, Rachel McNamara, Mark Kelson and Stephen Rollnick for all your support throughout this PhD. Your advice, help and support have been invaluable. I am so grateful to have such amazing supervisors to help me through this journey. I would not have been able to do it without you all. I would like to thank all the WILMA team for your support and advice. Thank you also to the WILMA participants for taking part in the study. Thank you to everyone in PCPH and SEWTU who have provided such a supportive environment. Thank you to everyone that helped with the development of the coding system and gave up your time to help me with the PhD. To my family you have supported me my whole life and have helped me get to where I am today. You have been there and listened to me talk about my PhD for the last 3 years. I am so grateful for all you have done for me, I wouldn’t be here without you. Thank you to all my friends who have always been there for me, who have distracted me when I need it and been there through the highs and the lows over the years. Finally thank you David, for everything! You have been by my side through this whole journey. You have listened to me every day, for the last 2 years, talk about my PhD and have kept me motivated. You have been my rock and my best friend. You have been my emotional support though all of this and I don’t have the words to say how much it means to me. i Summary Background Nearly a quarter of UK adults are obese representing a significant public health problem. Motivational interviewing (MI) may be effective in helping people to lose weight. Planning could be a mechanism of action which is related to outcome. The aim is to define the types of planning talk used by clients during an MI session and examine their relation to weight loss maintenance (WLM) outcomes. Also to examine the skills the therapist used prior to a client talking about planning. Methods To define planning talk a literature review was conducted and an expert group listened to recorded MI sessions. Thematic content analysis was used to identify the types of planning talk. Thematic analysis was used to identify the therapist skills prior to planning within 50 MI sessions. Associations between types of planning talk and WLM outcomes were analysed using logistic and linear regression. Results The development of the coding system found several types of plans/goals. The reliability was 86% and 75% agreement with the gold standard, for examples of plans/goals and the transcript respectively. Frequent planners lost on average 2.8 kgs (95% CI) and 1.2kg/m² (95% CI) more than those who were low planners (not statistically significant). Medium goal setters statistically significantly increased on average their weight (8.8kg) and BMI (3.5 kg/m²) compared to low goal setters. Therapist’s skills prior to planning were asking the client planning questions and exploring with the client their planning ideas in order to increase specificity. Conclusion The coding system can be used to code WLM data with acceptable reliability. A possible association between planning and a decrease in weight and BMI was demonstrated. Understanding how MI works could lead to improvements in the practice of MI by therapist, efficacy, focus research efforts and facilitate a better understanding of what helps people to change behaviours. ii Table of Contents 1. Chapter 1: Introduction .......................................................................................... 1 1.1 Introduction ........................................................................................................................ 1 1.2. Obesity: The problem......................................................................................................... 2 1.3 Weight loss interventions ................................................................................................... 2 1.4 Weight loss maintenance interventions ............................................................................. 3 1.5 Why motivational interviewing? ......................................................................................... 4 1.5.1 What is motivational interviewing? ............................................................................. 4 1.5.2 Motivational interviewing and weight loss maintenance ............................................ 5 1.6 The WILMA trial .................................................................................................................. 6 1.6.1 Sample .......................................................................................................................... 6 1.6.2 Method ........................................................................................................................ 6 1.6.3 Intervention delivery .................................................................................................... 7 1.6.4 Outcomes .................................................................................................................... 8 1.6.5 WILMA and MIMIC ..................................................................................................... 10 1.7 Rationale ........................................................................................................................... 11 1.7.1 Mechanisms and health promotion ........................................................................... 11 1.8 Planning............................................................................................................................. 12 1.9 Conclusions ....................................................................................................................... 12 1.10 Aims and research questions .......................................................................................... 13 1.11 Main research question .................................................................................................. 14 1.11.1 Key questions ........................................................................................................... 14 1.12Thesis structure ................................................................................................................ 14 2. Chapter 2: Background ............................................................................................ 15 2.1 Introduction ...................................................................................................................... 15 2.2 Weight loss maintenance: successful interventions ......................................................... 15 2.2.1 Bariatric surgery ......................................................................................................... 15 2.2.3 Diet, exercise and behaviour change techniques ...................................................... 17 2.2.4 Internet ...................................................................................................................... 20 2.2.5 Summary .................................................................................................................... 20 2.3 What is motivational interviewing? .................................................................................. 21 2.4 Theory and motivational interviewing .............................................................................. 22 2.4.1 Introduction ............................................................................................................... 22 2.4.2 Self-determination theory ......................................................................................... 22 2.4.3 Transtheoretical model