CONsensus-based Process evaluation reporting guideline for public HEalth intervention Studies (CONPHES) conducted alongside an effectiveness trial: an e-Delphi study

OBJECTIVES: Many researchers conduct a process evaluation alongside an effectiveness trial of a public health intervention to better understand mechanisms behind observed effects. Yet, there is no standardised, scientifically accepted guideline for reporting such process evaluations, which impedes interpretation and comparison of study results. The aim of this project was to develop a consensus-based and expert-based guideline for reporting process evaluations of public health interventions conducted alongside an effectiveness trial. DESIGN AND SETTING: We conducted an e-Delphi study with a large panel of international experts. PARTICIPANTS: Based on purposive sampling, we invited 137 international experts that had been involved in the design of process evaluations, researchers who published high-profile process evaluations or frameworks, editors of journals that publish process evaluations, and authors of other reporting guidelines. RESULTS: Based on a literature search, a first draft of the reporting guideline included 32 items, which was proposed to panel members during the first round. Of the invited 137 invited international experts, 73 (53%) participated in at least one round of the e-Delphi study. Participants rated the inclusion and comprehensibility of the proposed items on a 5-point Likert scale and provided comments and suggestions for relevance and definitions of the items. Adjustments to the items and descriptions were proposed to the e-Delphi panel until consensus of ≥67% for each individual item was reached. In total, 64 (88% of 73) completed round 2, and 55 (76% of 73) completed round 3. This resulted in 19 items that are included in the consensus-based process evaluation reporting guideline for public health intervention studies (CONPHES) guideline. The items cover a detailed description of the intervention that is evaluated, the implementation strategies applied, and underlying causal pathways, and the role of the delivery and support team. The guideline also requires describing the evaluation framework and how evaluation outcomes were assessed. Lastly, the guideline includes items on providing a detailed description of applied analyses (both quantitative and qualitative) and measures for assuring quality. The guideline is accompanied by an Explanation and Elaboration document, with a more detailed explanation of each item. CONCLUSIONS: We expect that the CONPHES reporting guideline for process evaluations of public health interventions can improve the reporting of process evaluations of interventions aimed at promoting public health. This can potentially facilitate more effective translation of public health research into practice and contribute to improving both individual and population health outcomes.