Evidence for lower threshold for diagnosis of hypertension: inferences from an urban-slum cohort in India

Background Hypertension (HTN) is a key risk-factor for cardiovascular diseases (CVDs). Blood-pressure (BP) categorizations between systolic blood pressure (SBP) of 120 and 140 remain debatable. In the current study we aim to evaluate if individuals with a baseline SBP between 130-140 mm Hg (hypertension as per AHA 2017 guidelines) have a significantly higher proportion of incident hypertension on follow-up, as compared to those with SBP between 120-130 mm Hg. Methods Secondary data analysis was performed in a community-based cohort, instituted, and followed since 2017. Participants were aged ≥30 years, residents of urban slums in Bhopal. BP was measured at or near home by Community Health Workers (CHWs). Two-year follow up was completed in 2019. We excluded participants who were on BP reduction therapy, had fewer than two out-of-office BP measurements and who could not be followed. Eligible participants were re-classified based on baseline BP in four categories: Normal (Category-A), Elevated-BP (Category-B), Variable-BP (Category-C) and reclassified HTN based on AHA-2017 (Category-D). Proportion of individuals who developed incident hypertension on follow up was primary outcome. Result Out of 2649 records, 768 (28.9%), 647 (24.4%), 586 (22.1%), 648 (24.4%) belonged to Categories A, B, C and D respectively. Incident HTN with cut-off of 140/90 mm Hg was, 1.6%, 2.6%, 6.7%, 12% in categories A, B, C and D respectively. Incidence of incident hypertension in individuals with a baseline SBP between 130-140 mm Hg (Category D) was significantly higher as compared to those with SBP between 120-130 mm Hg (Category B). Conclusion We conclude that biological basis for AHA-2017 definition of hypertension is relatively robust also for low income and resource-limited settings. Evidence from our longitudinal study will be useful for policy makers for harmonizing national guidelines with AHA-2017.