Evaluating implementation of the HEARTS model for management of hypertension and diabetes in Guatemala: protocol for a prospective observational hybrid type 3 study

The HEARTS model (Healthy-lifestyle counseling, Evidence-based treatment protocols, Access to essential medicines and technologies, Risk-based management, Team-based care, and Systems for monitoring) is recommended by the World Health Organization and the Pan American Health Organization to improve primary care management of hypertension, diabetes, and other cardiovascular disease risk factors in national health systems. The objective of this study is to evaluate HEARTS implementation in the Ministry of Health primary care system in Guatemala, where a scale-up project covering approximately 10% of the country began in 2024. This is a prospective, observational evaluation using a hybrid type 3 effectiveness-implementation design with three sequential periods: pre-implementation, implementation, and maintenance. The six HEARTS-aligned multilevel implementation strategies are: (1) training and supportive supervision for health workers, (2) standardized treatment protocols, (3) strengthening availability of medications and diagnostics, (4) task sharing with non-physician health workers, (5) quality monitoring systems, and (6) patient engagement and community outreach. The evaluation is guided by the RE-AIM (Reach, Effectiveness, Adoption, Implementation, and Maintenance) framework. Co-primary outcomes are hypertension and diabetes treatment rates (Reach), estimated from MOH administrative data using a difference-in-differences approach comparing intervention districts with non-HEARTS comparator districts. Additional quantitative outcomes include treatment intensity and retention (Reach), disease control (Effectiveness), district-level uptake (Adoption), strategy-specific fidelity (Implementation), and sustainment of outcomes after external support concludes (Maintenance). To explain variation in quantitative outcomes, semi-structured interviews will be conducted with MOH staff, government officials, international advisors, and civil society stakeholders using an explanatory sequential mixed methods design. The study will include a cost-effectiveness analysis and budget impact analysis to inform policy decisions on scale-up and sustainability. This study will provide evidence on HEARTS implementation in Guatemala. Findings will inform decisions about national scale-up and contribute to the global evidence base on implementation of hypertension and diabetes management in primary care health systems. This study is registered on the Open Science Framework ( https://osf.io/easm9 ).