Digital psychosocial intervention for older adults with subthreshold depression in primary care in Brazil (PRODIGITAL): protocol for an individually randomised controlled trial

Subthreshold depression is a substantial risk factor for the development of major depression. It is associated with poorer health, functional disabilities, and reduced quality of life in older adults. There is a paucity of cost-effective psychosocial interventions for this population in primary care worldwide, particularly in low- and middle-income countries. We present a protocol for evaluating the effectiveness and cost-effectiveness of the Viva Vida programme, a 6-week self-help digital psychosocial intervention for treating older adults with subthreshold depressive symptoms in primary care with a two-arm, individually randomised controlled trial with a 1:1 allocation ratio with integrated economic and process evaluations. We will include 450 individuals 60 years and older with subthreshold depressive symptoms (score between five and below 10 on the 9-item Patient Health Questionnaire (PHQ-9)), registered with one of the 46 primary care clinics in Guarulhos, Brazil. The Viva Vida programme will be delivered via automated audio and visual WhatsApp messages, with psychoeducation and behavioural activation content. It involves 48 messages, delivered twice daily, four days a week. Participants in the control arm will receive a single message with general information about depression. The primary outcome is the depressive symptoms at the three-month follow-up as measured by PHQ-9, which will be compared between study arms. The cost-effectiveness of the intervention will be assessed at five months. A detailed process evaluation will explore context and implementation outcomes. The Viva Vida programme is an innovative digital psychosocial intervention delivered via WhatsApp messaging without the participation of health professionals. The evaluation of the Viva Vida programme will contribute to the development of simple and cost-effective models of remote self-help interventions for reducing depressive symptoms among older adults with subthreshold depression in primary care. The protocol is registered with Registro Brasileiro de Ensaios Clinicos (ReBEC) (RBR-6c7ghfd).