The following report was abstracted from the article by VL Burt, et al.: Trends in the prevalence, awareness, treatment, and control of hypertension in the adult US population. Data from the Health Examination Surveys, 1960-1991. Hypertension 1995; 26: 60-69.

DETECTION AND CONTROL OF HYPERTENSION IN THE POPULATION USA EXPERIENCE

Patrick J. Mulrow, Professor of Medicine, Medical University of Ohio, Toledo, Ohio Secretary General, World Hypertension League

Abstract
Trends in prevalence, awareness, treatment, and control of hypertension in the adult US population are reported. The data are from the National Health and Nutrition Examination Surveys (NHANES) carried out in four separate surveys, the last being NHANES III 1988-1991. Age adjusted prevalence of hypertension at ( 160/95 mm Hg declined from 20% to 14%, and at ( 140/90 mm Hg declined from 36.3% to 20.4% in NHANES III. Hypertension awareness increased significantly to as high as 89% for those with blood pressures ( 160/95. For all people with blood pressure ( 160/95 nearly 64% have it controlled below that level, but only 29% have their blood pressure controlled below 140/90. Although the data from these surveys are encouraging, there are still too many people in the USA with uncontrolled hypertension.

Hypertension is a highly prevalent cardiovascular risk factor in the USA with nearly 50 million people having an elevated blood pressure. Data from USA Health Examination Surveys, 1960-1991, described the trends in prevalence, awareness, treatment, and control of hypertension in the adult US population (18-74 years of age).(1) Four separate national surveys were conducted: 1960-62, 1971-74, NHANES I, 1976-80 NHANES II, 1988-91 NHANES III.(2) For the last survey the threshold for defining hypertension was reduced from 160/95 to 140/90. Furthermore, over the years the methodology for measuring blood pressure has changed. In NHANES III, blood pressure was measured on two occasions. The first set of three blood pressures was measured in the subjects' home by a lay interviewer, and the second set by a physician on the mobile examination center. Both recorders underwent a training program for standardization of the blood pressure measurement. Several different sized blood pressure cuffs were used to account for large or obese arms. For systolic pressure the trained observers were instructed to record the first of two consecutive sounds as the systolic blood pressure. The diastolic pressure was the reading 2 mm Hg below where they heard the last sound. The blood pressure was measured while the subject was in the seated position.

Hypertension threshold varied over the years and is defined in earlier surveys as blood pressure of 160/95 mm Hg) or, in the latest survey (1988-91), as 140/90 mm Hg. Current treatment with antihypertensive drugs was also used as a criterion for the presence of hypertension.

Awareness of hypertension is the recognition by the patients that they have high blood pressure by the above definitions. Treatment is defined as the use of antihypertensive drugs at the time of the interview. Control of hypertension is defined as blood pressure 140/90 mm Hg in NHANES III or 160/95 mm Hg in previous surveys while taking antihypertensive drugs.

Results
Age adjusted prevalence of hypertension at 160/95 mm Hg declined from 20% to 14% in 1988-91 survey. Also, age-adjusted prevalence at 140/90 mm Hg declined from 36.3% to 20.4% (Fig. 1 see below). The distribution of blood pressure levels is shown in Figure 2 (see below). Most hypertensives are in Stage 1 (140/90 - 159/99 mm Hg).

Hypertension awareness increased substantially to 89% for 160/95 mm Hg and 73% for 140/90 mm Hg. For all people with hypertension 160/95 mm Hg, 64% now have it controlled below 160/95 mm Hg. However, only 29% have blood pressure controlled below 140/90 mm Hg ( Table 1 in pdf format . The PDF format requires Adobe Acrobat Reader to view, which can be downloaded free from www.adobe.com ).

For those being treated for hypertension the rate of control 140/90 mm Hg ranges from 47% for black men to 60% for white women (Table 1).

The class of drugs used for treatment in the USA has changed considerably from 1986 to 1995.(3) The prescriptions for diuretics have decreased about 20%, while calcium channel blockers and ACE inhibitors have increased five- to sixfold. In 1995 calcium channel blockers were the most prescribed antihypertensive drug.

Since 1971 hypertension prevalence has decreased and the systolic and diastolic pressure levels of the population have also decreased, systolic from 131 to 119 and diastolic from 78 to 73 mm Hg. Variation in blood pressure measurement techniques may account for some of the fall. Although there have been dramatic improvement in awareness and control, there are still many people who are unaware and untreated, or inadequately treated.

Acknowledgment

The author wishes to thank Dr. Edward J. Roccella for his advice and information.

Figure 1 shows the trends in age-adjusted prevalence of hypertension in the US population, ages 18-74 NHANES indicates National Health and Nutrition Examination Survey conducted by the National Center for Health Statistics, Centers for Disease Control and Prevention. The data for figure comes from reference 1, Burt et al., Hypertension 1995: 26:60-69.

Figure 2 is constructed from data in reference 1, Burt et al., Hypertension 1995: 26:60-69. It shows the distribution of blood pressure levels in the US population 18 and older. The blood pressure stages are defined in JNCV: Arch Intern Med 1993: 53:154-183.

References

  1. Burt VL, Cutler JA, Higgins M, Horan MJ, Labarthe D, et al.: Trends in the prevalence, awareness, treatment, and control of hypertension in the adult US population. Data from the Health Examination Surveys, 1960-1991. Hypertension 1995: 26:60-69.
  2. National Center for Health Statistics. Plan and operation of the third National Health and Nutrition Examination survey, 1988-94. Vital Health Stat 1994: 1(32). US Dept of Health and Human Services publication (PHS) 94-1308.
  3. Kaplan NM, Gifford Jr RW: Choice of initial therapy for hypertension. JAMA 1996:275:1577-1580.
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