Assessing fidelity measurements in school-based anxiety, depression and suicide prevention programs: a systematic review

Background: To ensure the effectiveness of school-based anxiety, depression and suicide prevention programmes, implementation fidelity, defined as the degree to which interventions are implemented as intended, is crucial. A comprehensive overview of fidelity measurements in these programmes is currently lacking, limiting the ability to compare and improve implementation efforts. This is particularly challenging in the context of scaling up prevention programmes, where ensuring both high-quality implementation and widespread adoption often proves insufficiently successful. With this review we aimed to (1) examine the extent to which fidelity measures were used and reported in existing studies of school-based anxiety, depression and suicide prevention programmes; (2) identify which fidelity components were measured; and (3) evaluate the quality of the fidelity measurements. Methods: A systematic search was conducted across PubMed, PsycINFO, Medline, and ERIC using an AND-combination of search terms related to schools, adolescents, depression and interventions. Two researchers screened the selected articles, with discrepancies resolved by a third. Pre-defined inclusion criteria were used based on school-based prevention programmes, controlled trials, and psychological intervention techniques. For data extraction, fidelity components were extracted together with the methods for fidelity measurement. The quality of the measurements was assessed using criteria used in earlier fidelity research. Results: Of 13,131 identified articles, 190 met our inclusion criteria. Of these, 72 (38%) measured at least one fidelity component, most commonly adherence (57, 79%), followed by responsiveness (24, 33%), dosage (19, 26%), and quality of delivery (9, 13%). Programme differentiation was not measured. The quality of fidelity measurements was most frequently moderate for adherence (65%), dosage (53%), and quality of delivery (56%), but low for responsiveness (79%). Conclusion: Most school-based anxiety, depression, and suicide prevention programmes lack fidelity measurements, and existing assessments are often of moderate to low quality. To improve fidelity measurement, future research should prioritise the development of standardised methods with clear definitions and practical tools for assessing fidelity components. Embedding fidelity as a central element in study designs is essential to better link implementation efforts to intervention outcomes and to fully understand and optimise programme effectiveness, while ensuring that fidelity can be feasibly monitored in real-world settings.