Strengths and limitations
depression, anxiety
A particular strength of this study is that it evaluates a workplace intervention that was implemented internationally and in three different sectors including people from various job roles and focusing on the previously neglected evidence of workplace mental health interventions in SMEs. The MENTUPP pilot helped us to examine impact differences between the different contexts and report on the applicability of our intervention among them. This is not only useful to inform the upcoming MENTUPP cRCT, but also for future research on global complex mental health interventions which is an underexplored field (Thornicroft and Patel A second strength of our study is that we relied on a theory driven approach to evaluate our complex intervention. In a first phase, we developed a ToC which visualizes the rationale and the mechanism of change of our intervention and describes on which outcomes MENTUPP is expected to generate an effect (Tsantila et al. Another advantage of this outcome evaluation study, is that it helped us to further optimize the content of the MENTUPP intervention, the implementation process and the evaluation strategy. We obtained initial evidence that mental wellbeing, anxiety and personal stigma towards depression and anxiety can be changed through our intervention and that several evaluation measures that we selected are able to capture this change. We believe that our intervention has potential to have an even greater impact on mental health and productivity loss if leaders receive during implementation more practical guidance on how to conduct positive changes in workload, emotional demands and conflicts in the workplace. Due to the COVID-19 pandemic, the amount of guidance provided during implementation was limited. Ahead of the MENTUPP cRCT, we optimized the materials embedded in the MENTUPP Hub, we worked out a more intense and interactive implementation approach focusing on important psychosocial factors and we selected more appropriate evaluation measures to assess burnout and productivity losses.A major limitation of this study, is the high dropout rate of respondents completing the follow-up measures. The low response rate does not allow a confirmatory interpretation of our findings. While some of our results are encouraging, we consider them as preliminary and are aware that more advanced research is needed to which the cRCT will contribute. The high dropout in this pilot study may have different reasons. First, it is possible that the evaluation part was too extensive for employees to complete. For the cRCT, the number of items used for the evaluation is halved. Second, COVID-19 has genuinely disrupted the implementation process of the MENTUPP pilot study and we are hopeful that the cRCT is safe from any COVID-19 measures. Third, it is also possible that the intervention did not match with the needs of leaders. Fourth, according to our findings it is more possible for males, and people working in the Construction to drop out. Moreover, through the dropout analysis we conducted, we noticed that almost 70% of the complete cases had a tertiary education. However, it is important to mention that this is perhaps not representative of the participating countries as according to evidence the percentage of people with tertiary education varies across them (OECD Finally, the validated scales we selected to assess the long-term outcomes of the intervention in their majority consist of negatively worded items while research focuses on the importance of the inclusion of positive aspects when mental health is evaluated (Bieda et al. 