Prognosis criteria of casual systolic and diastolic blood pressure values in a prospective study in India

BACKGROUND: In India, cardiovascular events are often diagnosed at lower blood pressures (BP) than in Western countries, questioning whether the actual World Health Organization cut-off points for hypertension (systolic BP (SBP) >or=140 mm Hg and/or diastolic BP (DBP) >or=90 mm Hg) are appropriate in low resource countries. METHODS: A large population-based cohort study including 167 331 adults aged 35-90 years, living in a rural area, was followed up during a 7-year mean duration for all-cause mortality and cardiovascular disease (CVD) deaths. At baseline, casual BP was measured, and lifestyle was assessed through a questionnaire. Death rates were calculated according to SBP and DBP, and their association was examined in a multivariate analysis, among all subjects, then stratified by sex and age groups. RESULTS: Forty-five per cent of the study subjects had hypertension. The nadir of CVD death rates was observed at 110 mm Hg for casual SBP and 75-80 mm Hg for casual DBP. In the multivariate analysis, SBP from 120 mm Hg and DBP from 90 mm Hg were significantly associated with risks of ischaemic heart disease and stroke. High SBP and DBP values were greater predictors of mortality in the young age group (34-44 years) than in the old age group (65+ years). SBP was a stronger independent predictor of CVD than DBP. CONCLUSIONS: SBP and DBP were associated with CVD mortality at thresholds lower than the current hypertension definition. Measurement limited to SBP alone would be effective in screening for CVD risk in large populations.