Background: Research on cultural adaptation of psychological interventions indicates that a higher level of adaptation is associated with a higher effect size of the intervention. However, direct comparisons of different levels of adaptations are scarce. Aims: This study used a smartphone-based self-help programme called Step-by-Step (Albanian: Hap-pas-Hapi) for the treatment of psychological distress among Albanian-speaking immigrants in Switzerland and Germany. Two levels of cultural adaptation (i.e., surface vs. deep structure adaptation) were compared. We hypothesised that the deep structure adaptation would enhance the acceptance and efficacy of the intervention. Method: We conducted a two-arm, single-blind randomised controlled trial. Inclusion criteria were good command of the Albanian language, age above 18, and elevated psychological distress (Kessler Psychological Distress Scale score above 15). Primary outcome measures were the total score of the Hopkins Symptom Checklist and the number of participants who completed at least three (out of five) sessions. Secondary outcomes were global functioning, well-being, post-traumatic stress, and self-defined problems. Results: Two-hundred-twenty-two participants were included, of which 18 (8%) completed the post-assessments. The number of participants who completed the third session was equal in both conditions, with N = 5 (5%) and N = 6 (6%) respectively. Discussion: Drop-out rates were high in both conditions, and no group difference was found regarding the acceptance of the intervention. The high drop-out rate stands in contrast with other trials testing Step-by-Step. Future research should examine cultural factors impacting recruitment strategies, as insights could help to reduce participant drop-out rates in clinical trials.
