Community Hypertension Control Using the Health Belief Model and PRECEDE-PROCEED

This protocol describes a community-based cluster randomized controlled trial in Kamalgonj Upazila, Moulvibazar district, Bangladesh, evaluating a theory-driven intervention to improve blood pressure (BP) control among adults with hypertension. The intervention is grounded in the Health Belief Model (HBM) and structured using the PRECEDE-PROCEED framework to address behavioural and structural barriers such as poor medication adherence, high salt intake, physical inactivity, inadequate fruit intake, tobacco use, fragmented care and limited access to affordable medicines. Formative mixed-methods research in the study communities showed high levels of uncontrolled hypertension despite treatment, frequent non-adherence, unhealthy diet and activity patterns, heavy smokeless tobacco use and reliance on informal providers. These findings informed the PRECEDE phases (social, epidemiological, behavioural/environmental, educational/ecological and administrative/policy assessments) and the selection of intervention targets. Twelve clusters (villages or wards of about 3,000-5,000 residents) will be randomised 1:1 to intervention or control, with around 40 participants per cluster (≈480 in total). Adults are eligible if they are ≥18 years, have physician-diagnosed hypertension or BP ≥140/90 mmHg on two occasions, have lived in the cluster ≥6 months and can provide informed consent; exclusions include severe comorbidities requiring intensive care, severe cognitive impairment and pregnancy or planned pregnancy within 12 months. Randomisation is stratified by urban/rural status and performed by an independent statistician, with outcome assessors and data analysts blinded where feasible. The sample size was calculated to detect a 5-7 mmHg difference in mean systolic BP at 12 months with 80% power, assuming a standard deviation of 20 mmHg, intracluster correlation of 0.02-0.05 and up to 15% loss to follow-up. The intervention consists of four components delivered over 12 months by