Impact of hypertension on mortality in adults in Moramanga, Madagascar: a retrospective cohort study in the community

BACKGROUND: Hypertension remains a global public health problem. This study aimed to evaluate the impact of hypertension on premature mortality among people living in Moramanga, Madagascar. METHODS: Three communes of Moramanga district have been monitored since 2012 as part of the MHURAM project (Moramanga Health Survey in Urban and Rural Areas in Madagascar). In 2013, individuals aged 15 years and above were surveyed to estimate the prevalence of hypertension and identify risk factors. A follow-up survey was conducted in 2016-2017 to record deaths; causes of death were assessed through verbal autopsy (VA). The occurrence of premature death was evaluated using a retrospective cohort study design applied to data collected from adults aged 30 to 70 who participated in the hypertension survey. Mortality rates and partial life expectancy by sex and hypertension status were estimated using survival analysis; covariates associated with premature risk of mortality were identified using a Cox proportional hazards model. The contribution of causes of death to the difference in partial life expectancy between hypertensive and non-hypertensive individuals was evaluated using a decomposition analysis. RESULTS: There were 4,472 participants in the hypertension survey aged between 30 and 70 during the follow-up. The average follow-up was 2.7 years per individual, resulting in 11,892 person-years in total with 117 deaths reported giving a mortality rate of 9.8‰ (13.1‰ for males and 7.1‰ for females). An estimated 3.2 years of life was lost among those diagnosed with hypertension compared to normotensive (32.0 years and 35.2 years respectively). Adjusted for gender, smoking habit, sedentary lifestyle, and wealth index, hypertension is a risk factor for premature death [HR = 1.58 95%CI (1.07-2.36)]. Hypertensive individuals also experienced higher all-cause and communicable disease mortality in people aged between 30 and 39 years. CONCLUSION: Hypertension is associated with higher risks of premature death in the community of Moramanga. In addition, hypertension contributes not only to mortality via cardiovascular diseases, but also through all causes combined. The health system should enhance prevention efforts, particularly for young hypertensive patients, when risk is most pronounced.