The National High Blood Pressure Education Program (NHBPEP) is approaching its thirtieth anniversary. During the past quarter century the NHBPEP has reported periodically prevalence estimates of hypertension as new data became available. The primary source of data for these estimates has been cross-sectional population studies conducted by the National Center for Health Statistics, Centers for Disease Control and Prevention, the National Health and Nutrition Examination Surveys (NHANES). In determining prevalence, actual blood pressure measures and self-reported information have been used. The earliest program statements defined high blood pressure as ≥160 mm Hg systolic or 95 mm Hg diastolic (160/95), or taking medication for hypertension.1 When clinical trial data reported the benefits of beginning to treat blood pressure at lower levels, the NHBPEP lowered the blood pressure threshold criteria for defining hypertension from 160/95 to 140/90 mm Hg.2 This resulted in more Americans being labeled as hypertensive. Although 140/90 mm Hg or taking medication for hypertension is the current criterion to define hypertension, evidence from many sources indicates that blood pressure is related to the risk of cardiovascular and renal diseases in a continuous manner, even below the 140/90 mm Hg cut-off point. The Third NHANES (NHANES III) is the current and best source of data to estimate hypertension prevalence in the United States. This survey was conducted in two phases. Phase 1 was performed from 1988 through 1991 and phase 2 from 1991 through 1994. Estimates of hypertension prevalence, and the methods used to generate them, have been previously reported for Phase 1, 1988–1991.3 Table 1 shows NHANES III prevalence estimates for the full 1988–1994 period for hypertension according to the following definition: systolic blood pressure ≥140 mm Hg, or diastolic ≥90 mm Hg, or taking medication for hypertension. These estimates are expressed in percent by age and gender for whites, blacks, and all races combined, with a midpoint of November 1991. They are for persons aged 18 and over, excluding persons in the military or in institutions such as prisons and nursing homes. Applying these conventional criteria to NHANES III data yields an estimate of 42.3 million adults who have high blood pressure. Prevalence (%) of hypertension in the united states, 1989–1994 Includes race/ethnic groups not shown separately due to small sample sizes. Prevalence (%) of hypertension in the united states, 1989–1994 Includes race/ethnic groups not shown separately due to small sample sizes. The conventional definition of hypertension excludes those individuals whose only evidence of hypertension was that they were told by a physician or other health professional that they had hypertension. This group includes those who have lowered their blood pressure <140/90 mm Hg by lifestyle changes. In NHANES III, the group of the adult population who were not classified as having hypertension according to the conventional definition, yet who reported having been told by a physician or other health professional two or more times that they had high blood pressure, made up 5.5% of the total adult population, or about 7.7 million individuals. Sixty-four percent of those reported using lifestyle changes to lower their blood pressure. Adding the 7.7 million who were told at least twice by their physician or other health professional that they had hypertension, to the 42.3 million from conventional criteria, yields 50 million adult hypertensives in the United States in the period 1988–1994. The true prevalence of isolated systolic hypertension cannot be determined from NHANES III data alone. This is because 51% of hypertensive persons are currently using medications to treat hypertension, and the blood pressure of the NHANES sample person before treatment is not known. For example, before diagnosis, a patient has elevated systolic and diastolic blood pressures. After being diagnosed and treated, the patient’s blood pressure decreases to the point where the diastolic blood pressure is normal, but the systolic blood pressure is still elevated. Then the patient’s blood pressure is measured during the NHANES examination. By the conventional criterion, he or she would be included in the category of isolated systolic hypertension.
Michael Wolz (2000) studied this question.