Theory and evidence-based development and feasibility testing of a weight loss intervention (Health4LIFE) for overweight and obese primary school educators employed at public schools in low-income settings, Western Cape Province, South Africa

Doctoral Thesis


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Background: Bearing in mind the prevalence of overweight/obesity found among educators (teachers) and their role modelling function, it is imperative that appropriate weight loss interventions are developed and implemented to control obesity in this target population, while ensuring that they model a healthy body size and lifestyle behaviours in their teaching environment. The United Kingdom (UK) Medical Research Council (MRC) state that best intervention development practice involves a systematic approach where best published research evidence and most suitable theories are combined, referred to as the ‘theory and evidence-based approach'. Intervention development should inherently consider behaviour change theories to assist researchers in deciding which theoretical constructs to target to achieve behaviour change. The MRC guidance recommends that following the development of an intervention, the next step should focus on feasibility testing to advise full-scale evaluation and implementation in real world settings. A feasibility study allows an intervention to be refined by either making incremental or simultaneous adaptations throughout the feasibility study, as well as during all phases of the development of the intervention. Aim: The aims of this research were to 1) conduct a theory and evidenced-based process to develop a weight loss intervention for overweight and obese primary school educators employed at public schools in low-income settings in the Western Cape Province, South Africa and 2) to test the feasibility of the developed intervention in a mixed methods study design. Intervention development Methods: This research firstly involved identification of an appropriate intervention development framework and then behaviour change theories for integration in the framework. The Behaviour Change Wheel (BCW) integrated with the Theory of Planned Behaviour (TPB) to gain insight in educator beliefs regarding dietary and physical activity behaviours and the Health Belief Model (HBM) to address the concept of health awareness (first step to behaviour change) were selected. The Step approach to Message Design and Testing (SatMDT) tool was chosen to underpin intervention message development. The systematic process approach applied in the development of the weight loss intervention in this research included five overarching stages, namely 1) identifying the target behaviours for weight loss, 2) understanding the behaviour, 3) identifying the intervention options, 4) identifying the content and implementation options, and 5) testing and refinement of the intervention materials. Key considerations that emerged in various steps that determined decisions regarding delivery format, are as follows: target population specific factors, setting, affordability, access to electronic devices and internet, limited or no professional contact and preference regarding weight loss intervention delivery mode. Outcome: Step by step application of the BCW framework combined with the TPB, the HBM and the SatMDT resulted in the development of the self-help Health4LIFE weight loss intervention consisting of three elements: 1) a wellness day, 2) a hard copy self-help manual and 3) 80 text messages sent over a 16-week period. The discussion of this section of the thesis focuses on critiquing the use of a theorybased approach (BCW combined with the TPB, HBM and SatMDT) in intervention development. Feasibility testing/assessment Methods: Feasibility outcomes that were identified for the purposes of this research included reach, applicability, acceptability, implementation integrity (primary outcomes), and signals of effect in terms of belief patterns (diet and physical activity beliefs), stage of change for dietary and physical activity behaviours, lifestyle behaviours (diet and physical activity) and weight (secondary outcomes). A cluster sampling method was used to randomly select public schools within the Metro North District in the Western Cape Province. These schools were contacted and educators were invited to participate in the wellness day and the subsequent intervention. Random sampling of schools was repeated until the target of 20 schools was achieved. Ten of these schools were then randomly assigned to the control and 10 to the intervention group. Three sub-studies were conducted to assess the feasibility outcomes. Sub-study 1 involved testing the intervention in a pilot randomised controlled trial. The intervention group received the Health4LIFE weight loss intervention, and the control group received a hard copy of the Department of Health's ‘Choose a Healthy Lifestyle' booklet. Analysis to assess within group change and differences between groups for within group change over the 16- week period were done by protocol, thus using data for completers only. Sub-study 2 investigated the perceptions of educators who participated in the intervention arm and sub-study 3 the perceptions of principals of participating schools regarding reach, acceptability, applicability and implementation integrity. Results: Recruitment (n= 137) and drop-out (n=52) statistics indicated that reach was acceptable, with the exception of male educators who were underrepresented, and black African educators and educators who had attempted weight loss before who were more likely to drop-out. Barriers that may compromise school participation include interruption of teaching time, prior commitments by schools/educators, an already full school program and need to obtain permission from the Department of Basic Education (DoBE) for deviations from the normal school day. Qualitative inputs from principals and educators supported acceptability and applicability of the intervention They were positive about the wellness day, approved of implementation in the school setting, found the hard copy manual useful, enjoyable and easy to understand, and considered the text messages to be helpful and motivational for the day. It was evident that aspects that may need refinement include self monitoring activities, low frequency of contact with interventionists and arrangement of visits to the school. The planned implementation procedure (wellness day, engagement with most sections in the manual and sending of text messages) went as intended, reflecting good implementation integrity, with the exception of the drop-out of three entire schools due to scheduling challenges. Clear signals of effect were evident. The Health4LIFE intervention resulted in favourable shifts in belief patterns regarding dietary intake and physical activity; favourable shifts in stage of change for “increase fruit intake” and “decrease sugar intake”, significant changes in some lifestyle behaviours (increased intake of low fat food items, increased intake of vegetables, decreased intake of sugary food items, decreased frequency of adding fat and sugar to food, increase in physical activity and decreased time spent being sedentary) and a trend towards weight loss in the intervention group. The only significant changes in the control group related to dietary intake (increased intake of vegetables and increased intake of low-fat foods). Overarching conclusions and recommendations: Although the time and effort required to follow a systematic process using the BCW cannot be denied, at the end of this process a very clear understanding of the determinants of a specific behaviour and the mechanisms of action required to affect behaviour change is achieved. These insights are imperative for identification of the most appropriate intervention delivery mode and development of the intervention content. This research provides a comprehensive and systematic guide to using the BCW in a theory and evidence-based process for the development of a self-help weight loss intervention. Results reflecting reach, acceptability, applicability, implementation integrity and potential effectiveness of the Health4LIFE intervention support feasibility of the intervention. Material signals of effect in terms of shifts in belief patterns and stage of change, as well as improvements in lifestyle behaviours were evident. It is plausible that these shifts and changes could collectively result in weight loss, as a trend towards weight loss were found. These signals of effect warrant further evaluation of the intervention in a full-scale study and/or consideration for implementation by the DoBE. Based on the feasibility outcomes it is recommended that the following minor refinements of the Health4LIFE intervention receive attention before next steps are taken: recruitment of male educators, drop-out of black African educators and those who have attempted weight loss before, lack of DoBE policies to address educator health and wellbeing, educator suggestions to improve the intervention manual and poor completion of self-monitoring activities. Major intervention refinements that emerged from the feasibility testing for consideration include more frequent in-person contact between educators and interventionists, extending intervention duration, and making use of eHealth options for contact sessions and self-monitoring. However, the feasibility of major refinements would require additional investigation, further extending the already lengthy intervention development process. Bearing this in mind, implementation of the Health4Life intervention in public schools in low-income settings in its current format, but with minor changes to the hard copy manual as recommended by educators, should be considered.