Strengths, Limitations, and Practical Implications
This research has several strengths. The fact that the study was conducted in different work environments, disciplines, and countries allowed the results to represent different working conditions. Furthermore, the Kelaa Mental Resilience app is grounded both in theory (ie, the JDR model [Some limitations also need to be considered when interpreting our results. First, the sample is not representative of the general working population as there was an overrepresentation of female participants and the educational level of the participants was high. Thus, the results might not be generalized to other workplace settings. Second, the scales used to assess our outcomes may not have been sensitive enough to capture smaller changes that occurred. Additionally, as a technical constraint, the range of answers sometimes exceeded the size of the mobile phone screen and would have required scrolling to see the full scale, which may have resulted in an overrepresentation of the scores displayed on the screen. Third, the intervention was personalized according to the workers’ profiles, making it difficult to identify which elements contributed to the effects found. For such analyses, more data points and a larger data set would be needed. Fourth, participants were not blinded to the intervention allocation, which may have increased the bias. Fifth, attrition during the study was high; 47.2% of the participants had dropped out at the postintervention time pint (T2), while 50.1% had dropped out at follow-up (T3). Such high attrition adds bias to the results of the study, as it might have resulted in a self-selection mechanism and therefore limit the conclusions drawn from the study, consequently affecting the internal validity of the results. Related to this, the Kelaa Mental Resilience app might not have been suitable for everyone, again resulting in a self-selection mechanism and high attrition rates.A broader scope of the app content could result in a more applicable intervention for a larger variety of users. High attrition rates can also suggest that better communication strategies are needed in the trial sites to increase users’ engagement. Generally, understanding the needs of the target population may lead to better outcomes by providing them with an intervention fitting their needs [