Fidelity review: A scoping review of the methods used to evaluate treatment fidelity in behavioural change interventions

Objectives: To identify the definitions used for treatment fidelity in the behaviour change literature and to explore the extent to which the assessment of fidelity has been reported according to the five domains by Bellg et al.Methods: Three databases (Scopus, Medline Ovid and CINAHL) were searched. Results were limited to studies published between 2012 and 2015. Definitions/summaries of treatment fidelity used were recorded. Methods for assessing/monitoring treatment fidelity were extracted, summarised and categorised according to the five domains.Results: Sixty-five papers were included for analysis. A definition of treatment fidelity was provided by n = 34 studies; n = 9 defined fidelity according to Bellg et al. In the context of treatment fidelity, n = 9 (13.8%) reported on study design; n = 22 (33.8%) reported on an element of training of providers; n = 59 (90.7%) papers reported on delivery of treatment; n = 13 (20%) reported on receipt of treatment; and n = 10 (15.3%) reported on enactment of treatment skills.Conclusion: The definitions of treatment fidelity in the literature and the extent to which it has been reported were limited. Delivery of treatment was the most frequently reported component of treatment fidelity but other important aspects were poorly reported. The potential consequence of this is that translation of research interventions into clinical practice may not be optimised.