Association of blood pressure and cardiovascular mortality in India: Mumbai cohort study

Abstract

Background: To determine all-cause and circulatory system (cardiovascular)-related mortality in subjects with different grades of hypertension, we performed a prospective study.

Methods: A total of 148,173 individuals aged > or =35 years were recruited in Mumbai, India in years 1991-1997. Clinical history and anthropometric data were obtained and hypertension-categorized using US 7th Joint National Committee guidelines into normal, prehypertension, stage-I, and stage-II. These subjects were followed to ascertain vital status from 1997 to 2003. Multivariate analysis was performed using Cox proportional analyses and adjusted hazard ratios (HRs), 95% confidence intervals (CIs) determined for mortality in various hypertension grades.

Results: At baseline, hypertension was in 47.3% men and 45.7% women, while prehypertension in 40.8% men and 35.9% women. In total, 13,261 persons died during average 5.5 years follow-up of whom 9,259 deaths were matched and coded using International Classification of Diseases-10. Compared to those with normal blood pressure (BP), all cause mortality (HR, 95% CI) was significantly greater in stage-II (men 1.41, 1.31-1.52; women 1.46, 1.30-1.64). Circulatory system deaths were significantly more in stage-II (men 2.05, 1.77-2.39; women 2.06, 1.62-2.61) as well as stage-I (men 1.31, 1.14-1.52; women 1.39, 1.10-1.77). Subjects with stage-II hypertension had greater risk of death from hypertensive heart disease (men 2.77, 1.75-4.40; women 3.04, 1.73-5.35), ischemic heart disease (men 1.87, 1.54-2.28; women 1.85, 1.29-2.65), and cerebrovascular diseases (men 3.50, 2.42-5.05; women 3.09, 1.77-5.39).

Conclusions: In urban Indian subjects, compared to normal BP stage-II hypertension is associated with increased risk of all-cause mortality, while both stage-II and stage-I hypertension with circulatory system-related mortality.