Limitations to the RCT
LEAKAGE
The main limitation to the study were the unexpected differences in baseline levels of sickness absence between the two arms of the study (see discussion above). The study was also curtailed in some of its aims due to the onset of restrictions due to the COVID-19 pandemic that severely altered work practices and limited access of the researchers to the employees of the DVLA. Finally, the data on sickness absences could only be provided to the research team at the level of “groups” rather than individuals due to Data Protection issues. Hence, we were unable to examine the relationship between mental health literacy and stigma (as measured by the SASS) and sickness absence, or to data at the individual level. Future studies may benefit from research designs that are able to tie sickness rates to specific demographics such as history of mental health problems, gender, ethnicity, time in current employment, etc.The study was also unable to prevent any “leakage” and contamination of the Prevail programme from people in the active arm of the study to those in the control arm despite efforts to do so via using cluster randomisation. However, it should be emphasised that any such leakage would have served to reduce the differences between the active and control arms the study and thus be conservative to our hypotheses.Our original protocol for the study [Finally, while our data are supportive of the efficacy of Prevail they are not able to distinguish which parts of the Prevail intervention are effective (and which may not be). Indeed, part of the effect of Prevail may be accounted for by “placebo effects” in that merely taking part in any intervention that brings mental health and mental wellbeing to the forefront of peoples’ attention may be beneficial to mental wellbeing and therefore have effects on attitudes to mental health and in reduced sickness absences. Indeed, participants taking the Prevail intervention commented that the open acknowledgement of mental health challenges and stressors in the workplace led to feelings of validation and value by the employer.