Abstract
BackgroundThe implementation of a complex intervention is heavily influenced by individual context. Variation in implementation and tailoring of the intervention to the particular context will occur, even in a trial setting. It is recognised that in trials, evaluating the process of implementation of a complex intervention is important, yet process evaluation methods are rarely reported. The WAVES study is a cluster randomised controlled trial to evaluate the effectiveness of an obesity prevention intervention programme targeting children aged 6–7 years, delivered by teachers in primary schools across the West Midlands, UK. The intervention promoted activities encouraging physical activity and healthy eating. This paper presents the methods used to assess implementation of the intervention.MethodsPrevious literature was used to identify the dimensions of intervention process and implementation to be assessed, including adherence, exposure, quality of delivery, participant responsiveness, context, and programme differentiation.ResultsMultiple methods and tools were developed to capture information on all these dimensions. These included observations, logbooks, qualitative evaluation, questionnaires and research team reflection.DiscussionData collection posed several challenges, predominantly when relying on teachers to complete paperwork, which they saw as burdensome on top of their teaching responsibilities. However, the use of multiple methods helped to ensure data on each dimension, where possible, was collected using more than one method. This also allowed for triangulation of the findings when several data sources on any one dimension were available.ConclusionsWe have reported a comprehensive approach to the assessment of the implementation and processes of a complex childhood obesity prevention intervention within a cluster randomised controlled trial. These approaches can be transferred and adapted for use in other complex intervention trials.Trial registration numberISRCTN97000586
Highlights
The implementation of a complex intervention is heavily influenced by individual context
We have reported a comprehensive approach to the assessment of the implementation and processes of a complex childhood obesity prevention intervention within a cluster randomised controlled trial
Where differences arose on questions requiring a subjective response (e.g. Quality of delivery), a discussion took place to clarify what was expected for different quality ratings and explanatory text added to the checklist to improve future consistency. This process was repeated during the initial stages of the intervention implementation until high inter-rater reliability was achieved, and at least once per term to ensure consistency was maintained
Summary
The implementation of a complex intervention is heavily influenced by individual context. It is recognised that in trials, evaluating the process of implementation of a complex intervention is important, yet process evaluation methods are rarely reported. One frequent criticism of such trials is the difficulty in explaining the process by which the interventions have had the observed effects and distinguishing the relative contribution of intervention components. To address this there is increasing emphasis on evaluating intervention processes [2,3], including monitoring and reporting the fidelity of intervention implementation (i.e. whether the intervention is delivered as intended) and assessing contextual influences on intervention delivery and outcomes. There is a need to report the development and implementation of process evaluation methods
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