4. Discussion
depressive, WL, anxiety
IMI, MINOR, SECONDARY
In this three-group randomized controlled trial (RCT), we evaluated the effectiveness of two different versions (unguided, UG; guidance on demand, GoD) of the internet- and mobile-based intervention (IMI) StudiCare Mindfulness (StudiCare-M) for college students compared with a waitlist control group (WL). We found that both versions of StudiCare-M significantly improved mindfulness and various other outcomes of mental health compared with WL, with effects generally remaining stable after 6 months. Additionally, we compared the two versions against each other and found effectiveness of UG and GoD to be similar overall. We also did not find any significant differences concerning intervention satisfaction or negative effects between UG and GoD groups. However, GoD participants showed a significantly higher follow-up adherence after 6 months. For the primary outcome of mindfulness, we found large effects (Concerning secondary outcomes of mental health, we mostly found significant small to moderate effects in both the GoD and UG version of StudiCare-M. The effects on depressive, anxiety, and stress symptoms (The fact that we did not find substantial differences in effectiveness between the GoD and UG versions of StudiCare-M overall is in line with previous evidence comparing guided and unguided mindfulness-based IMI [Regarding long-term effectiveness of mindfulness-based IMIs, Somers-Spijkerman and colleagues [Concerning adherence, only about 20% of UG and 28% of GoD participants fulfilled our pre-defined criterion of completing 5 out of 7 modules 8 weeks after randomization, despite the incorporation of adherence-fostering intervention design (both UG and GoD) and additional guidance on demand (GoD). This rate could be considered somewhat low compared with previous research, where adherence to mindfulness-based IMI was found to range between 36% and 92% [In contrast to effectiveness, we did find follow-up adherence to be significantly higher in GoD vs. UG (UG) 6 months after randomization (39.3% vs. 28.1%; average completed modules: 4 vs. 3). Because GoD uptake was very low (20%), this finding suggests that simply being assigned an e-coach already results in improved adherence. Additionally, the number of e-coach contacts predicted adherence and the number of completed modules predicted mindfulness at post-assessment. This is consistent with the hypothesis that guidance might enhance effectiveness via increased adherence [Surprisingly, we found the subscription to the SMS coach to be a superior predictor of adherence compared with guidance (GoD vs. UG). This finding suggests that adherence can also be effectively promoted via persuasive design elements such as technical forms of guidance, e.g., chatbots [Finally, concerning negative effects of StudiCare-M, we only found one case of reliable deterioration on the primary outcome of mindfulness in the UG condition and none in GoD. Only around 15% of participants reported negative effects of mostly minor intensity and no one reported suicidal ideation, with similar results in UG and GoD. Britton et al. [