Pathways leading to success and non-success: a process evaluation of a cluster randomized physical activity health promotion program applying fuzzy-set qualitative comparative analysis

BACKGROUND: Health promotion programs can only lead to improvements in health outcomes if they are effectively implemented. However, most studies assessing implementation success focus on only one condition, although more conditions influence this process. Therefore, evidence is scarce on what conditions play a role in successful implementation and how they interact. Hence, we aimed to identify which combinations of teacher and implementation process characteristics affected the emotional and social school experience (SCE) of pupils participating in a school-based health promotion program. METHODS: This study was part of an effectiveness and process evaluation including 24 intervention and 27 control classes. We used fuzzy-set qualitative comparative analysis (fsQCA) to identify combinations of conditions that were associated with either an increase or no increase in the outcome SCE in comparison to the control group at 20 months post intervention. We deductively selected five conditions based on the Consolidated Framework for Implementation Research: teachers’ perceived self-efficacy, teachers’ expectations of the benefits of the intervention, teachers’ previous knowledge about the intervention, dosage of physical activity breaks, and quality of the implementation. RESULTS: We identified five different pathways that led to no increase in the pupils’ outcome (parameters of fit: consistency 94%, coverage 66%). The combination of an unsatisfying quality of implementing the intervention and a low previous knowledge about the intervention showed the highest empirical relevance. Similarly, fewer physical activity breaks in combination with other conditions impeded the program’s success. Furthermore, we identified two different pathways characterizing ways to success (consistency: 81%, coverage: 52%). The most relevant combination was good quality implementation of physical activity breaks, implemented by teachers with a high self-efficacy, and a good previous knowledge about the intervention. CONCLUSIONS: QCA has potential for an in-depth analysis of complex interventions as it can rely on small to medium sample sizes and analyze pathways to success and non-success separately. The investigated program can be improved by considering the following suggestions: The quality of the implementation process should be monitored during the implementation phase, and regular feedback loops and learning opportunities for teachers should accompany a program. Clear recommendations regarding the dosage should be established. TRIAL REGISTRATION: German register of clinical studies: DRKS00000622. Retrospectively registered: December 3, 2010, (http://www.drks.de/drks_web/setLocale_EN.do). Approved by the Ethics Committee of Lower Austria (GS4-EK-4/107–2010). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12889-018-6284-x) contains supplementary material, which is available to authorized users.