Integrating a self-guided cognitive behavioral therapy app (CONEMO) into Brazilian primary health care: protocol for a hybrid type III implementation-effectiveness study

Background: Depression and anxiety are common and disabling mental health conditions. Although cognitive behavioral therapy (CBT) is an evidence-based treatment, access remains limited, particularly in low- and middle-income countries. Internet-delivered CBT (iCBT) may expand access to psychological interventions, but integrating digital interventions into routine primary care remains challenging. This study protocol describes the implementation of CONEMO (Emotional Control), a self-guided iCBT app for depression and anxiety symptoms, in primary care units in 2 municipalities in Brazil. Methods: This mixed-methods hybrid type III implementation-effectiveness study is being conducted in primary care units in Indaiatuba and Jaguariúna, São Paulo, Brazil. Adults screening positive for depression (Patient Health Questionnaire-9 score ≥10) or anxiety (Generalized Anxiety Disorder-7 score ≥10) are offered a six-week CONEMO app-based intervention supported by a WhatsApp chatbot and a monitoring dashboard for primary care professionals. Primary outcomes are implementation outcomes, including penetration, acceptability, feasibility, and safety, assessed using app usage data, self-report measures, and focus groups with users, health professionals, and managers. Secondary outcomes include changes in depression, anxiety, and insomnia symptoms, quality of life, and behavioral activation over 12 weeks. Quantitative data will be analyzed using mixed-effects models. No formal sample size calculation was performed because the intervention is offered to all eligible users in participating units. Discussion: Recruitment began in January 2026 and is expected to continue through December 2026. As of October 2026, approximately 400 participants had been enrolled, and the intervention was available in 21 primary care units across the 2 municipalities. Expansion to additional units in Jaguariúna is planned, with 28 units expected to participate. The study will generate evidence on the integration of a digital mental health intervention into routine primary care and identify barriers and facilitators to implementation and scale-up in Brazil. DECLARAÇÃO DE USO DE INTELIGÊNCIA ARTIFICIAL (IA): During the preparation of this work, the authors used Claude Haiku 5.5 (Anthropic), a generative artificial intelligence (AI) tool, to assist with organizing and formatting the references and revising the manuscript for adherence to the journal’s guidelines, including rewording sections. The authors reviewed and edited all AI-assisted content and take full responsibility for the content of the published article.