Assessing implementation fidelity in a child maltreatment pilot trial: Lessons for evaluating complex interventions.

OBJECTIVE: This paper evaluates the implementation fidelity of Family Partner, a home-visiting intervention from the child welfare service that aims to reduce child maltreatment in families with complex support needs. METHOD: To assess implementation fidelity, we utilized self-reported routine data from practitioners delivering the intervention, comprising 1657 reports concerning 19 enrolled families. Furthermore, five in-depth qualitative interviews and two focus groups were conducted with practitioners. Descriptive analyses were conducted on quantitative data, and thematic analysis on the qualitative data. RESULT: The critical components for the implementation of the Family Partner intervention were generally met, with the exception of the requirement to conduct three home visits within the first 10 days of the intervention. Additionally, the quality and structure of the practitioner-reported routine data presented challenges in accurately assessing fidelity. CONCLUSIONS: Our study demonstrates the importance of developing robust measures for assessing implementation fidelity during the early stages of pilot testing before proceeding to a full-scale randomized controlled trial. Future research should include thoughtful and predefined fidelity measures to strengthen the evaluation of complex interventions.