Prevalence of Hypertension and Controlled Hypertension --- United States, 2005--2008

Nora L. Keenan, PhD1

Kimberly A. Rosendorf, MHS2

1National Center for Chronic Disease Prevention and Health Promotion, CDC

2National Center for Health Statistics, CDC

Corresponding author: Nora L. Keenan, PhD, Division for Heart Disease and Stroke Prevention, 2877 Brandywine Road, MS K-47, Atlanta, GA 30341. Telephone: 770-488-6487; Fax: 770-488-8334; E-mail: nlk0@cdc.gov.

Hypertension is a serious public health challenge in the United States, affecting approximately 30% of adults (1,2) and increasing the risk for heart disease and stroke, the first and third leading causes of death in the United States* (3). Racial/ethnic and socioeconomic disparities in hypertension prevalence in the United States have been documented for decades (4). Non-Hispanic blacks have a higher risk for hypertension and hypertension-related complications (e.g., stroke, diabetes, and chronic kidney disease) than non-Hispanic whites and Mexican Americans (2,4). Between 1999--2000 and 2007--2008, the prevalence of hypertension did not change, but control of hypertension increased among those with hypertension (1,5). Despite considerable improvements in increasing awareness, treatment and control of hypertension, in 2007--2008, approximately half of adults with hypertension did not have their blood pressure under control (1). Because of the fundamental role of hypertension in cardiovascular health, Healthy People 2010 includes national objectives to reduce the proportion of adults aged ≥20 years with hypertension to 14% from a baseline of 26% (objective 12-9) and to increase the proportion of adults aged ≥18 years with hypertension whose blood pressure is under control to 68% from a baseline of 25% (objective 12-10) (6,7).

To estimate age-adjusted hypertension prevalence and control among persons aged ≥18 years, CDC analyzed combined National Health and Nutrition Examination Survey (NHANES) data from two survey periods: 2005--2006 and 2007--2008.† NHANES is a nationally representative survey of the noninstitutionalized U.S. civilian population. Data are collected annually but released in 2-year cycles. NHANES includes a home interview and a physical examination at a mobile examination center where blood pressure is measured. Participants were selected through a complex, multistage sampling probability design. During 2005--2008, the response rate among persons in the sample was 76.4%.§ Data were analyzed for 10,488 participants for whom adequate interview and examination data were collected to determine hypertension status.

Blood pressure is measured by averaging two or three blood pressure readings taken during the physical examination in the NHANES mobile examination center. A detailed description of the procedures for blood pressure measurement in NHANES has been published elsewhere (8). Adults are categorized as having hypertension if they have a systolic blood pressure (SBP) ≥140 mm Hg, have a diastolic blood pressure (DBP) ≥90 mm Hg, or report that they are taking high blood pressure medication (9). Controlled hypertension is defined as SBP <140 mm Hg and DBP <90 mm Hg among persons with hypertension. Pregnant women were excluded from all analyses. Hypertension prevalence and control estimates were analyzed by demographic factors (i.e., sex, age group, race/ethnicity, marital status, education level, foreign-born status, family income,¶ health insurance status,** veteran status, and disability††) and health factors (i.e., diabetes§§ and obesity¶¶).

Statistical analyses accounted for the complex survey design and were age adjusted to the 2000 U.S. standard population. Univariate t-tests were used to assess significant differences between groups. Trend tests were used to evaluate associations with age, education, and income. All significance tests were two-sided, with p<0.05 as the level of statistical significance. For comparison of estimates by variables with more than two categories, adjustments for multiple comparisons were made using the Bonferroni method by dividing 0.05 by the number of comparisons (10).

The overall age-adjusted prevalence of hypertension among persons aged ≥18 years for 2005--2008 was 29.9%. Substantial differences (>10%) in hypertension by age group, race/ethnicity, education, family income, foreign-born status, health insurance status, diabetes, obesity, and disability status were evident during 2005--2008 (Table). Although differences in hypertension prevalence by marital status and sex were also statistically significant, the differences were ≤10%. Hypertension prevalence increased with age and decreased with increasing education and income level. Non-Hispanic blacks had higher levels of hypertension (42.0%) than non-Hispanic whites (28.8%) and Mexican Americans (25.5%). U.S.-born adults had higher levels of hypertension (30.8%) than foreign-born adults (24.9%). Persons with diabetes had a significantly higher prevalence of hypertension than those without diabetes (57.3% versus 28.6%), as did those who were obese compared with those who were not (39.8% versus 25.8%) and those with a disability compared with those with no disability (39.3% versus 29.3%). Adults aged <65 years with public insurance had higher levels of hypertension (32.1%) than those with private insurance (20.2%) and those with no insurance (20.0%).

During 2005--2008, the overall age-adjusted prevalence of hypertension control among persons with hypertension aged ≥18 years was 43.7% (Table). Men, adults aged 18--44 years, Mexican Americans, foreign-born, and persons without health insurance had a lower prevalence of hypertension control than their counterparts. Adults aged 18--44 years (37.5%) had a lower rate of hypertension control than adults aged 45--64 years (48.9%). The proportion of controlled blood pressure was similar among non-Hispanic blacks (41.2%) and non-Hispanic whites (46.5%) but was substantially lower among Mexican Americans (31.8%). Controlled hypertension was also lower among those classified as not obese compared with those who were obese (39.8% versus 47.5%), persons without diabetes compared with those with diabetes (41.7% versus 56.9%), and persons with no disability compared with those with a disability (41.1% versus 54.1%). Controlled hypertension was not associated with education or income.

The findings in this report are subject to at least four limitations. First, NHANES data are restricted to the noninstitutionalized population; thus, results from this study are not generalizable to persons who live in nursing homes or prisons or to military personnel. Second, reliable data were not available for certain racial/ethnic groups or sexual orientation. Only non-Hispanic blacks and Mexican Americans were oversampled; consequently, estimates cannot be calculated for other racial/ethnic populations (e.g., American Indians/Alaska Natives [AI/ANs], Asians/Native Hawaiians/other Pacific Islanders [A/PIs], or other Hispanics). Third, the cross-sectional study design provides a one-time only assessment of blood pressure, even though the blood pressure might be measured multiple times during one visit. This one-time assessment can overestimate or underestimate hypertension prevalence. However, the standardized measurement of blood pressure in a mobile examination center makes NHANES the best source of national data on hypertension. Finally, this study does not examine time trends in disparities to assess progress towards eliminating disparities. Although other studies included time trends, only a limited number of demographic characteristics such as race/ethnicity, age, and sex were examined (1,5).

These findings highlight the need for 1) expanded surveillance efforts to provide more data within populations, particularly for those most at risk for hypertension (i.e., persons with prehypertension, all blacks, and adults aged ≥45 years) and 2) augmented population-based strategies to prevent and control hypertension, particularly for those most at risk for hypertension-related cardiovascular disease (i.e., adults aged ≥65 years, blacks, and persons with hypertension, diabetes, or chronic kidney disease). The American Heart Association recommends such strategies in the Guide for Improving Cardiovascular Health at the Community Level (11), which uses the evidence-based recommendtions for single health behaviors at the community level from The Task Force on Community Preventive Services. Strategies include those related to assessment, education, community organization and partnering, ensuring personal health services, environmental change, and policy change. Specific recommendations include tracking blood pressure levels and identifying groups at high risk for hypertension; raising awareness about the importance of hypertension prevention and control in the prevention of cardiovascular disease and stroke; and promoting healthy lifestyle changes through education in the community, classroom, and work sites with tailored materials to accommodate for limited literacy and for culture and language diversity as well as improved access to healthy foods and places to exercise.

Uncontrolled hypertension contributes to premature death (death before age 75 years) from heart disease and stroke. In 2006, the age-adjusted years of potential life lost (YPLLs) for heart disease per 100,000 population aged <75 years were higher for blacks (1,969 YPLLs) and AI/ANs (1,009) than for whites (986), Hispanics (687), and A/PIs (472) (12). Blacks also had the highest YPLLs for stroke (432), compared with Hispanics (185), AI/ANs (178), A/PIs (164), and whites (158).

To prevent and control hypertension, the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) recommends lifestyle modifications, including maintaining a healthy body weight; adopting a diet rich in fruits, vegetables, and low-fat dairy products with reduced levels of saturated and total fat; reducing sodium intake; participating in regular aerobic physical activity; and limiting alcohol consumption (no more than two drinks per day for men and one drink per day for women). For hypertension control, JNC 7 also provides treatment guidelines for antihypertensive medications (9). One recommendation, reducing salt intake, has considerable potential for preventing and controlling hypertension. On the basis of predictive modeling of the health benefits of reduced salt intake on blood pressure, a populationwide reduction in sodium of 1,200 mg/day can reduce the annual number of new cases of coronary heart disease by 60,000--120,000 cases and stroke by 32,000--66,000 cases (13). The Dietary Guidelines for Americans 2005 used evidence from clinical trials about hypertension and salt sensitivity (14) to recommend that specific groups (e.g., persons with hypertension, all middle-aged and older adults, and blacks) limit sodium intake to 1,500 mg/day (15). The specific groups comprise approximately 70% of the U.S. population (16). On the basis of 2005--2006 NHANES data, the average sodium intake is 3,466 mg/day, and only 9.6% of all adults did not exceed their applicable recommended limit of sodium (17). In 2010, the Institute of Medicine published recommendations for reducing sodium consumption, including a recommendation for mandatory national standards for the sodium content of foods, an interim strategy of voluntary action, and a series of supporting strategies, which includes ensuring and enhancing sodium-related monitoring (18). In one such strategy, New York City, in a partnership of cities, states, and national health organizations, set voluntary benchmarks for lowering the average sodium level in 62 categories of packaged food and 25 categories of restaurant food. Sixteen companies have committed to meeting at least one target for packaged or restaurant food within 2--4 years.***

Another IOM report published in 2010 recommended a population-based policy and systems change approach to prevent and control hypertension rather than interventions designed for individuals directly (19). For example, policy and system changes could help persons with hypertension by ensuring that they are receiving care consistent with current guidelines and receiving effective antihypertensive medication if needed. An action plan for making home blood pressure monitoring (HBPM) a part of routine management of hypertensive patients includes the recommendation that patients be reimbursed for a monitor and that their health care provider be reimbursed for services related to patients using HBPM (20). A systematic review of interventions assessing health risks with feedback to change employees' health reviewed 31 studies that included blood pressure assessment plus health education with or without other interventions (21). The authors concluded that the results were in favor of such interventions.

CDC will continue to monitor progress in achieving Healthy People hypertension-related objectives to provide national data for program planning and as a basis for action when progress is not achieved or worsens. In addition, progress should be monitored within demographic groups most at risk for hypertension and hypertension-related morbidity and mortality, the groups who are also most in need of population-based strategies to reduce sodium in foods.

References

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