Problem Management Plus (PM+) for common mental disorders in Chilean primary care: a feasibility randomized controlled trial of a transdiagnostic psychological intervention

Abstract Background In Chile, more than one-third of the total disability burden is attributable to mental disorders, yet public mental health services in primary care present coverage gaps. This randomized controlled trial evaluated the feasibility, acceptability, and preliminary effects of Problem Management Plus (PM+) delivered individually by general health professionals in Chilean primary care. PM+ is a World Health Organization transdiagnostic psychological intervention that may help address these service gaps through task shifting. Methods Adults ( n = 56) attending a public primary care center in Valdivia, Chile, with symptoms of depression and/or anxiety were randomized to PM+ ( n = 28) or treatment as usual (TAU) ( n = 28). Primary outcomes were feasibility (including recruitment and retention proportion, and adherence), fidelity (assessed with audio recordings), and acceptability (assessed with the Abbreviated Acceptability Rating Profile (AARP) and the Acceptability of Intervention Measure (AIM)). Secondary outcomes were the following clinical measures: depressive symptoms (measured with the Patient Health Questionnaire-9 Item (PHQ-9)), anxiety symptoms (Generalized Anxiety Disorder-7 Item (GAD-7)), and self-identified problems (Psychological Outcomes Profile (PSYCHLOPS)). Analyses of covariance (ANCOVA) were used to estimate adjusted effects, standardized using Hedges’ g. Results The recruitment proportion was 67%, retention was 88%, and the adherence of participants averaged 4 PM+ sessions. PM+ achieved “sufficient” fidelity and was highly acceptable to participants (AARP mean: 43.6/48) and facilitators (AIM mean: 17.2/20). A total of 49 participants were analyzed at the post-intervention time point. With ANCOVA models adjusted for baseline scores and days to intervention initiation, PHQ-9 scores (depressive symptoms) were lower in the PM+ group than in the TAU group, although the difference was not statistically significant (7.4 vs. 10.3; p = 0.073, Hedges’ g = 0.54). GAD-7 scores (anxiety symptoms) were lower in the PM+ group, but no statistically significant difference was observed (7.1 vs. 7.5; p = 0.767, Hedges’ g = 0.09). PSYCHLOPS scores (intensity of self-identified problems) were significantly lower in the PM+ group (7.2 vs. 11.2; p = 0.006, Hedges’ g = 0.86). Conclusions PM+ was feasible, acceptable, and showed moderate-to-large potential effects on self-identified problem intensity and depressive symptoms, supporting its suitability for larger-scale testing in Chile. Trial registration ClinicalTrials.gov ID: NCT06988332 ( https://clinicaltrials.gov/study/NCT06988332 ). Registration was conducted before participant recruitment began. 2025-04-24.