Increased variance in blood pressure distribution and changing hypertension prevalence in an urban Indian population.

The objective of the study was to determine trends in age-specific blood pressure (BP) distribution and hypertension prevalence in an urban Indian population. In successive hypertension epidemiological studies (1995 and 2002), randomly selected 2212 subjects (1412 men, 797 women) in the first and 1123 subjects (550 men, 573 women) in the second study were evaluated. BP was measured using World Health Organization guidelines and hypertension diagnosed using the American Joint National Committee-VI report. Age-specific BP levels in the first and the second study were determined and compared. The mean values of systolic and diastolic BP were not significantly different in various age groups in the first and the second studies. There was an increased variance in the second study as denoted by the significant increase in standard deviations and coefficients of variation in systolic as well as diastolic BP levels at age groups > or =50 years in men and > or =40 years in women (P<0.05). The age-adjusted prevalence of hypertension (known or BP > or =140/> or =90 mmHg) in the first study was 29.5% (men) and 33.5% (women), and in the second study was 30.0% (men) and 30.3% (women) (P=NS). In the second as compared to the first study, there was decrease in age-adjusted prevalence of stage I hypertension (men 16.8 vs 24.9%, women 15.4 vs 27.5%), and increase in stage II hypertension (men 11.7 vs 2.8%, women 18.8 vs 3.1%), and combined stage II and III hypertension (men 13.5 vs 4.7%, women 16.7 vs 6.0%) (P<0.01). This change was associated with greater prevalence of obesity in the second study. In conclusion, increased systolic and diastolic BP dispersion over a 7-year period in this urban population is associated with unchanged hypertension prevalence, decline in stage I hypertension and upsurge in more severe grades. Increasing environmental factors, particularly obesity, appear important.