Effectiveness of a task-sharing collaborative care model for identification and management of depressive symptoms in patients with hypertension attending public sector primary care clinics in South Africa: pragmatic parallel cluster randomised controlled trial

•Collaborative care for comorbid depressive symptoms in patients on hypertension treatment that includes referral to a task sharing lay counselling service is neither superior nor inferior to referral to mental health specialists.•In contexts where specialist resources are scarce, the use of lay counsellors within a collaborative care approach to increase access to psychological treatments for depressive symptoms is supported.•The need for implementation science to enhance our understanding of how to promote identification and referral of moderate-severe to severe comorbid depressive symptoms in patients with uncontrolled hypertension in primary health care facilities is needed. We tested the real-world effectiveness of a collaborative task-sharing model on depressive symptom reduction in hypertensive Primary Health Care (PHC) patients in South Africa. A pragmatic parallel cluster randomised trial in 20 clinics in the Dr Kenneth Kaunda district, North West province. PHC clinics were stratified by sub-district and randomised in a 1:1 ratio. Control clinics received care as usual (CAU), involving referral to PHC doctors and/or mental health specialists. Intervention clinics received CAU plus enhanced mental health training and a lay counselling referral service. Participant inclusion criteria were ≥ 18 years old, Patient Health Questionnaire-9 (PHQ-9) score ≥ 9 and receiving hypertension medication. Primary superiority outcome was ≥ 50% reduction in PHQ-9 score at 6 months. Statistical analyses comprised mixed effects regression models and a non-inferiority analysis. Trial registration number: NCT 02425124. Between April 2015 and October 2015, 1043 participants were enrolled (504 intervention and 539 control); 82% were women; half were ≥ 55 years. At 6 and 12 months follow-up, 91% and 89% of participants were interviewed respectively. One control group participant committed suicide. There was no significant difference in the primary outcome between intervention (N=256/456) and control (N=232/492) groups (55.9% versus 50.9%; adjusted risk difference = -0.04 ([95% CI = -0.19; 0.11], p = 0.6). The difference in PHQ-9 scores was within the defined equivalence limits at 6 and 12 months for the non-inferiority analysis. The trial was limited by low exposure to depression treatment by trial participants and by observed co-intervention in control clinics Incorporating lay counselling services within collaborative care models does not produce superior nor inferior ou