Fidelity in workplace mental health intervention research: A narrative review

The scientific literature on workplace interventions that target individual-level determinants of mental health for primary or secondary prevention is mixed, with many studies failing to show statistically significant, sizeable effects. A methodological characteristic that may explain these mixed findings is fidelity, a multidimensional construct that captures the extent to which an intervention is implemented as intended, in a standardized manner. In this narrative review, we examined the extent to which workplace mental health intervention studies try to enhance or measure the twelve different dimensions of fidelity that have been identified. We conducted comprehensive searches of MEDLINE, Embase, and PsycINFO. Following review, 370 articles were selected for inclusion, of which only 21% explicitly mentioned fidelity. About two-thirds of the articles considered less than half of all relevant fidelity dimensions. Most studies tried to enhance rather than measure fidelity. Only a handful of included studies (n=7, 2%) measured half or more of all relevant fidelity dimensions. Some fidelity dimensions (e.g. theoretical) were considered less often than others (e.g. receipt and enactment). Our review shows that fidelity is insufficiently considered in current workplace mental health literature. We discuss implications for internal and external validity, scalability, and directions for future research.