Measuring implementation fidelity of school-based obesity prevention programmes: a systematic review.

Background: Until now, there is no clear overview of how fidelity is assessed in school-based obesity prevention programmes. In order to move the field of obesity prevention programmes forward, the current review aimed to 1) identify which fidelity components have been measured in school-based obesity prevention programmes; 2) identify how fidelity components have been measured; and 3) score the quality of these methods.

Methods: Studies published between January 2001-October 2017 were selected from searches in PubMed, EMBASE, PsycINFO, CINAHL, Cochrane Library and ERIC. We included studies examining the fidelity of obesity prevention programmes (nutrition and/or physical activity and/or sitting) at school (children aged 4-18 year) measuring at least one component of implementation fidelity. A data extraction was performed to identify which and how fidelity components were measured. Thereafter, a quality assessment was performed to score the quality of these methods. We scored each fidelity component on 7 quality criteria. Each fidelity component was rated high (> 75% positive), moderate (50-75%) or low (< 50%).

Results: Of the 26,294 retrieved articles, 73 articles reporting on 63 different studies were included in this review. In 17 studies a process evaluation was based on a theoretical framework. In total, 120 fidelity components were measured across studies: dose was measured most often (N = 50), followed by responsiveness (N = 36), adherence (N = 26) and quality of delivery (N = 8). There was substantial variability in how fidelity components were defined as well as how they were measured. Most common methods were observations, logbooks and questionnaires targeting teachers. The quality assessment scores ranged from 0 to 86%; most fidelity components scored low quality (n = 77).

Conclusions: There is no consensus on the operationalisation of concepts and methods used for assessing fidelity in school-based obesity prevention programmes and the quality of methods used is weak. As a result, we call for more consensus on the concepts and clear reporting on the methods employed for measurements of fidelity to increase the quality of fidelity measurements. Moreover, researchers should focus on the relation between fidelity and programme outcomes and determine to what extent adaptations to programmes have been made, whilst still being effective.