Background Evidence-based interventions (EBIs) can be effective tools for the prevention of disease and health promotion. However, their implementation often requires a delicate balance between the need to adjust the intervention to the context in which it is implemented and the need to keep the core components that make the intervention effective. This so-called dilemma between fidelity and adaptation is often handled by health professionals in the sustainment phase of an implementation (i.e., once the intervention has been adopted and institutionalized in an organization), but not much is known about how and to what extent health professionals are affected by this dilemma. Focusing on the sustainment phase, this project aims to study (1) how fidelity and adaptation are managed by professionals using an EBI, (2) how the fidelity–adaptation dilemma affects professionals’ psychosocial working conditions, and (3) how a structured decision support influences professionals’ management of the dilemma and their psychosocial working conditions. Methods The study is set in Sweden, and the EBI in focus is a parental program (All Children in Focus). A longitudinal within-person intervention design is used, combined with a cross-sectional survey design. Data sources include web-based questionnaires, brief interviews, fidelity ratings, paper-and-pen questionnaires, and written documentation, collected at multiple time points with both group leaders and parents as respondents. Discussion This project approaches fidelity and adaptation from the perspective of the professionals that manage EBIs during the sustainment phase of implementation. Although it is well known that EBIs continue to change over time, it remains to be understood how the fidelity–adaptation dilemma can be managed so that the effectiveness of interventions is retained or improved, not diluted. Moreover, the project adds to the literature by presenting an occupational health perspective on the fidelity–adaptation dilemma. It is acknowledged that fidelity and adaptation may have consequences for not only clients but also the occupational wellbeing of the professionals managing the dilemma, and subsequently, their willingness and ability to deliver EBIs in a sustainable way.

IntroductionAdaptations are often necessary to effectively translate evidence-based interventions (EBI) between contexts, but compliance with the EBIs' core components is still important, which is referred to as the fidelity–adaptation dilemma. In the sustainment phase of implementation, it is the professionals delivering the EBIs who are tasked with the decision-making regarding adaptations, but the currently used models and frameworks mostly focus on the initial phases of implementation. To better understand and guide professionals in using EBIs, there is a need to explore professionals' perceptions of the fidelity–adaptation dilemma. The aim of this study is consequently to explore how professionals perceive and navigate the fidelity–adaptation dilemma when using an EBI out of context.Materials and MethodsSemi-structured interviews were held with 19 psychologists working in primary care. The interviews concerned EBIs in general and Cool Kids, an evidence-based parenting education program designed for children with anxiety that is now used for children with lower levels of anxiety in another setting. The data were analyzed using an inductive content analysis method.ResultsThe analysis resulted in two themes: My standpoint regarding fidelity and adaptation is clear and Managing fidelity and adaptations is complicated. The first theme summarizes the professionals' perceptions of confidence for either favoring fidelity or adaptations, as well as reasons for why they made adaptations. For the second theme, the professionals expressed concern about sometimes meeting difficulties with the dilemma when following their original inclination and having second thoughts about the impact the adaptations have in practice.ConclusionThe professionals generally had strong preferences regarding fidelity and adaptations, but neither preference prevented them from facing difficulties with the dilemma. The results point to a need for better information about possible adaptations from developers but also better support and guidance for professionals when implementing EBIs to ensure quality implementation and facilitate implementation. The results of this study can inform the design of support for professionals in managing the dilemma.