IMPORTANCE: Depression and anxiety are common mental disorders globally but are rarely recognized or treated in low-income settings. Task-shifting of mental health care to lay health workers (LHWs) might decrease the treatment gap. OBJECTIVE: To evaluate the effectiveness of a culturally adapted psychological intervention for common mental disorders delivered by LHWs in primary care. DESIGN, SETTING, AND PARTICIPANTS: Cluster randomized clinical trial with 6 months' follow-up conducted from September 1, 2014, to May 25, 2015, in Harare, Zimbabwe. Twenty-four clinics were randomized 1:1 to the intervention or enhanced usual care (control). Participants were clinic attenders 18 years or older who screened positive for common mental disorders on the locally validated Shona Symptom Questionnaire (SSQ-14). INTERVENTIONS: The Friendship Bench intervention comprised 6 sessions of individual problem-solving therapy delivered by trained, supervised LHWs plus an optional 6-session peer support program. The control group received standard care plus information, education, and support on common mental disorders. MAIN OUTCOMES AND MEASURES: Primary outcome was common mental disorder measured at 6 months as a continuous variable via the SSQ-14 score, with a range of 0 (best) to 14 and a cutpoint of 9. The secondary outcome was depression symptoms measured as a binary variable via the 9-item Patient Health Questionnaire, with a range of 0 (best) to 27 and a cutpoint of 11. Outcomes were analyzed by modified intention-to-treat. RESULTS: Among 573 randomized patients (286 in the intervention group and 287 in the control group), 495 (86.4%) were women, median age was 33 years (interquartile range, 27-41 years), 238 (41.7%) were human immunodeficiency virus positive, and 521 (90.9%) completed follow-up at 6 months. Intervention group participants had fewer symptoms than control group participants on the SSQ-14 (3.81; 95% CI, 3.28 to 4.34 vs 8.90; 95% CI, 8.33 to 9.47; adjusted mean difference, -4.86; 95% CI, -5.63 to -4.10; P < .001; adjusted risk ratio [ARR], 0.21; 95% CI, 0.15 to 0.29; P < .001). Intervention group participants also had lower risk of symptoms of depression (13.7% vs 49.9%; ARR, 0.28; 95% CI, 0.22 to 0.34; P < .001). CONCLUSIONS AND RELEVANCE: Among individuals screening positive for common mental disorders in Zimbabwe, LHW-administered, primary care-based problem-solving therapy with education and support compared with standard care plus education and support resulted in improved symptoms at 6 months. Scaled-up primary care integration of this intervention should be evaluated. TRIAL REGISTRATION: pactr.org Identifier: PACTR201410000876178.
