Bridging the evidence gap: a qualitative COM-B analysis of facilitators and barriers to evaluating heat-health action plans in Germany

Background Extreme heat and heat waves are increasing in intensity, duration, and frequency. The World Health Organization recommends the development of heat-health action plans (HHAPs) for public health protection. In Germany, districts and federal states have started to implement HHAPs. However, reports on ongoing evaluations as well as evidence on the effectiveness and efficiency of planned or implemented measures are scarce. We aimed to explore the perspectives of professionals in heat and health protection on current evaluation practices, focusing on perceived facilitators of and barriers to the evaluation of HHAPs at different stages. Methods We interviewed 23 professionals with expertise or leadership responsibility from the field of heat and health working in public administration at the district, federal state, and national level, or nongovernmental organizations (NGOs) throughout Germany. By conducting thematic analysis following a hybrid combination of deductive and inductive coding within the COM-B model, we derived and categorized facilitators of and barriers to evaluating HHAPs. Additionally, we clustered them into individual, organizational, and policy levels based on the Socioecological Model. Results Although all interviewees perceived the evaluation of HHAPs as important, evaluation procedures were rarely systematically realized in practice. Interviewees emphasized the importance of opportunities such as political support as well as a clear mandate and assignment for evaluation. Moreover, structural conditions, like the absence of guidelines and standards for evaluation, data infrastructure, personnel, and funding, were reported to often hinder evaluation, resulting in limited experience and knowledge in evaluating complex interventions such as HHAPs. Collaboration and networks were reported as facilitative in process evaluation. While individual motivation was not reported as a reason for not evaluating HHAPs, a combination of identified barriers often contributed to feeling overwhelmed with the task of evaluation. Conclusions Our findings suggest that evaluation is not consistently institutionalized in German heat-health action planning. Barriers to evaluating HHAPs are not primarily related to individual or district-level motivation, but rather limited by opportunity and capability shaped within political and institutional conditions. To institutionalize HHAP evaluation, greater political commitment, supportive structures, data infrastructures, and guidance for evaluation, as well as targeted funding and personnel are required.