A Systematic Review of SMS Reminder Efficacy for Youth Retention in the HIV Care Cascade in Harare, Zimbabwe

Retention of youth in the HIV care cascade is a persistent challenge in sub-Saharan Africa. In Harare, Zimbabwe, specific barriers hinder sustained engagement with HIV services among young people. Short Message Service (SMS) reminders have been proposed as a low-cost intervention to support adherence and retention. This systematic review aimed to synthesise evidence on the effectiveness of SMS reminder systems for improving youth retention within the HIV care cascade in Harare, Zimbabwe. It evaluated reported outcomes, identified implementation factors, and delineated evidence gaps. A systematic search of peer-reviewed literature was conducted across multiple electronic databases. Pre-defined inclusion criteria focused on studies evaluating SMS-based interventions for youth living with HIV in Harare. Studies were screened, selected, and data extracted independently by two reviewers. Study quality was assessed using appropriate appraisal tools. Five studies met the inclusion criteria. Evidence indicates SMS reminders may positively influence appointment adherence and antiretroviral therapy collection rates. One randomised controlled trial reported improved clinic attendance in the intervention group. Common themes included the importance of message content, timing, and youth privacy concerns. The methodological rigour and outcome measures of included studies varied. SMS reminders show potential as a supportive tool for enhancing youth retention in HIV care in this setting. However, the evidence base is limited by a small number of heterogeneous studies, precluding definitive conclusions on optimal implementation or sustained impact across the entire care cascade. Further robust, longitudinal research is required. Programmatic implementation should be contextually adapted, address privacy concerns, and be integrated within a broader package of youth-friendly services. Future studies should employ standardised outcome measures to facilitate comparison and meta-analysis. HIV, youth, adolescents, retention, care cascade, SMS reminders, mHealth, Zimbabwe, Harare This review consolidates the available evidence on SMS reminders for youth HIV care retention in Harare, informing local policy and programme design while highlighting critical directions for future research.