TRENDS IN THE PREVALENCE, AWARENESS, TREATMENT, AND CONTROL OF HYPERTENSION IN THE ADULT US POPULATION - DATA FROM THE HEALTH EXAMINATION SURVEYS, 1960 TO 1991

The objective of this study was to describe secular trends in the dist ribution of blood pressure and prevalence of hypertension in US adults and changes in rates of awareness, treatment, and control of hyperten sion. The study design comprised nationally representative cross-secti onal surveys with both an in-person interview and a medical examinatio n that included blood pressure measurement. Between 6530 and 13 645 ad ults, aged 18 through 74 years, were examined in each of four separate national surveys during 1960-1962, 1971-1974, 1976-1980, and 1985-199 1. Protocols for blood pressure measurement varied significantly acros s the surveys and are presented in detail. Between the first (1971-197 4) and second (1976-1980) National Health and Nutrition Examination Su rveys (NHANES I and NHANES II, respectively), age-adjusted prevalence of hypertension at greater than or equal to 160/95 mm Hg remained stab le at approximately 20%. In NHANES III (1988-1991), it was 14.2%. Age- adjusted prevalence at greater than or equal to 140/90 mm Hg peaked at 36.3% in NHANES I and declined to 20.4% in NHANES III. Age-specific p revalence rates have decreased for every age-sex-race subgroup except for black men aged 50 and older. Age-adjusted mean systolic pressures declined progressively from 131 mm Hg at the NHANES I examination to 1 19 mm Hg at the NHANES III examination. The mean systolic and diastoli c pressures of every sex-race subgroup declined between NHANES II and III (3 to 6 mm Hg systolic, 6 to 9 mm Hg diastolic). During the interv al between NHANES II and III, the threshold for defining hypertension was changed from 160/95 to 140/90 mm Hg. Hypertension awareness has in creased substantially at both thresholds, to 89% and 73% for 160/1995 and 140/90 mm Hg, respectively. Compared with only 16% of all people w ith hypertension being <160/95 mm Hg in 1960-1962 and 1971-1974, 64% o f all people with hypertension now have it controlled to below the 160 /95 mm Hg threshold but only 29% to below 140/90 mm Hg. For people wit h treated hypertension, the rate of control (<140/90 mm Hg) ranges fro m 47% of black men to 60% of white women. Hypertension prevalence in t he United States has declined progressively since 1971, and the distri butions of systolic and diastolic pressures have shifted downward duri ng the approximately 30-year period between 1960-1962 and 1988-1991. V ariation in blood pressure measurement techniques may explain some of the decline in prevalence and the downward shift in distribution. Hype rtension awareness, treatment, and control also have improved tremendo usly during the same period, accounting for much of the shift at the u pper end of the distribution. Despite these favorable trends, many peo ple with hypertension are unaware of their condition, and many more ar e untreated or inadequately treated.