Figure. Mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) by sex and age: National Health and Nutrition Examination Survey 1999-2000.
Wang Y, Wang QJ. The Prevalence of Prehypertension and Hypertension Among US Adults According to the New Joint National Committee GuidelinesNew Challenges of the Old Problem. Arch Intern Med. 2004;164(19):2126-2134. doi:10.1001/archinte.164.19.2126
The recently released Seventh Report of the Joint National Committee (JNC) on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure provides a new classification of blood pressure levels. Little is known about the current situation of elevated blood pressure in the United States, according to the new guidelines.
Cross-sectional analysis of national representative data collected from 4805 adults 18 years and older surveyed in the 1999-2000 National Health and Nutrition Examination Survey. We examined the prevalence of prehypertension and hypertension according to the new JNC guidelines, people’s awareness and management of hypertension, and the differences across sociodemographic and body weight groups.
Elevated blood pressure is a serious problem in the United States. Approximately 60% of American adults have prehypertension or hypertension, and some population groups, such as African Americans, older people, low-socioeconomic-status groups, and overweight groups, are disproportionately affected. The prevalence of hypertension has increased by approximately 10 percentage points during the past decade. The awareness and appropriate management of hypertension among hypertensive patients remain low: 31% were not aware of their disease, only two thirds (66%) were told by health professionals to adopt lifestyle modifications or take drugs to control hypertension, and only 31% controlled their hypertension.
With 60% of the population affected, the United States is facing a serious challenge in the prevention and management of prehypertension and hypertension. People’s awareness and control of hypertension remain poor. This study highlights the seriousness of the problem and the importance of promoting lifestyle modifications.
On May 14, 2003, the National High Blood Pressure Education Program Coordinating Committee of the National Heart, Lung, and Blood Institute released the Seventh Report of the Joint National Committee (JNC) on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (the JNC 7 report).1 The new report was developed because, since the last report (JNC 6, released in 1997),2 important new evidence has emerged from observational and clinical trials of hypertension management. The JNC 7 report synthesizes this evidence, and it also specifically simplifies the classification of blood pressure (BP) levels to maximize guideline implementation. According to the new report, normal BP is defined as systolic BP (SBP) less than 120 mm Hg and diastolic BP (DBP) less than 80 mm Hg; a SBP of 120 to 139 mm Hg or a DBP of 80 to 89 mm Hg is defined as prehypertension. The low-end threshold for prehypertension is lower than the previous designation of high-normal BP (ie, SBP/DBP: 130/85, JNC 6) (Table 1). Hypertension is still classified using cutoff points of SBP of 140 mm Hg or higher or DBP of 90 mm Hg or higher. The report emphasizes that even slightly elevated BP increases cardiovascular risk. Beginning at a SBP/DBP of 115/75 mm Hg, the risk of cardiovascular disease doubles with each increment of 20/10 mm Hg. The committee recommends lifestyle modifications for all patients with prehypertension and the addition of drug therapy for prehypertensive patients who have other compelling indicators, including multiple diseases.1
Clearly, these new guidelines have broadened the target population for high BP (HBP) control. However, little is known about the scope of the current HBP problem in the United States. Some studies have suggested that the prevalence of hypertension declined in the 1980s.3- 5 However, available data show that despite the extensive promotion of earlier JNC guidelines, hypertension awareness, treatment, and control in the United States remain poor.3- 8 Most previous studies regarding the national situation with regard to HBP-related problems are based on data collected before the mid-1990s, such as the Third National Health and Nutrition Examination Survey (NHANES III) data collected in 1988-1994. A thorough investigation of the situation according to the new guidelines, using more recent national representative survey data, is thus of great interest to policy makers, health care professionals, and the general public. The latest NHANES, a national representative survey conducted in 1999-2000, collected data on measured BP and questions about detection, management, and treatment of hypertension.9 This provides an excellentopportunityto help understand the current HBP-related problems in the United States. In this article, we report the national prevalence of prehypertension and hypertension defined according to the new JNC guidelines using the 1999-2000 NHANES data. We also study American adults’ awareness, management, and treatment of hypertension. Finally, we examine the differences in all of these factors across sociodemographic groups.
The 1999-2000 NHANES, conducted by the National Center for Health Statistics, Centers for Disease Control and Prevention, is a cross-sectional, nationally representative health examination survey. It covers a nationally representative sample of the US civilian, noninstitutionalized population, which was selected using a complex, stratified, multistage probability cluster sampling design.9 It provides a national estimate for the US population. In this study, 4805 adult men and women 18 years or older with complete data on BP measures were included. Using standardized techniques and equipment, BP was measured on all participants aged 8 years and older either in a mobile examination center (MEC) or during a home examination for participants who were 50 years or older and unable to travel to the MEC. Three and sometimes 4 BP measures were taken by 2 physicians in the MEC setting and 2 health technologists in the home examination setting, all following the latest American Heart Association recommendations on how to determine BP with sphygmomanometers.10 The computer-assisted personal interview method was used in the home examination. More details of the study methods are provided in the NHANES Laboratory/Medical Technologist Procedures Manual.9
Participants were separated into the following 4 groups based on their measured BP (average SBP and DBP, Table 2) and their answers to questions related to hypertension: (1) normal blood pressure: SBP less than 120 mm Hg and DBP less than80 mm Hg; (2) prehypertension (not hypertension): SBP of120mm Hg or higher but lower than 140 mm Hg or DBP of80mm Hg or higher but lower than 90 mm Hg; (3) hypertension: SBP of 140 mm Hg or higher or DBP of 90 mm Hg or higher or taking antihypertensive medication; and (4) prehypertension or hypertension: all those who had prehypertension orhypertension.
The following 2 questions were asked in the survey: (1) “Have you ever been told by a doctor or other health professional that you had hypertension?” and (2) “Were you told on 2 or more different visits that you had hypertension?” If a person answered “yes” to either question, he or should was classified as being aware of his or her hypertension status.
Participants who answered “yes” to at least 1 of a number of questions regarding whether they had ever been told by their physicians or other health care professionals to take prescriptions or adopt lifestyle modifications for controlling for their BP were classified as being told to control for hypertension.
Participants who answered “yes” to any 1 of a number of questions regarding whether they currently take prescriptions or have adopted a certain lifestyle modification were classified as having management of hypertension. Patients who currently take antihypertensive medication were classified as having treatment and if their SBP was less than 140 mm Hg and DBP was less than 90 mm Hg as having their hypertension controlled (ie, control of hypertension).
Based on measured weight and height data collected in the MEC, body mass index (BMI; a measure of weight in kilograms divided by the square of height in meters) was calculated for each participant. Participants were grouped into 3 categories: (1) nonoverweight (BMI less than 25); (2) overweight (BMI of 25 or more but less than 30); and (3) obese (BMI of 30 or higher). Pregnant women were excluded in the analysis stratified by body weight status.
For most age-related comparisons, participants were separated into 3 groups (18-39, 40-59, and ≥60 years) following the recommendation of the National Center for Health Statistics. More groups were not used due to the smaller sample size of the 1999-2000 NHANES compared with previous NHANES surveys.
Based on self-reported information, participants were grouped as non-Hispanic white, non-Hispanic black, Mexican American, and all others.
Income variables have not been released yet. Thus, we chose to use people’s reported education levels (less than high school, high school, more than high school) as the indicator of socioeconomic status.
All analyses took into account the unequal selection probabilities and the complex sample design by using the sampling weights. Our focus is to provide a national estimate of the problems. Standard errors were calculated with SUDAAN software using the jackknife “leave-one-out” procedure (National Center for Health Statistics, 2002). We stratified our analysis by age, sex, ethnicity, education levels, and body weight status. Statistical hypotheses were tested univariately at the.05 level using the 2-tailed t test; however, statistical testing is not emphasized in this study. Data management and statistical analysis were conducted using SAS statistical software (version 8.1; SAS Institute Inc, Cary, NC), and SUDAAN statistical software, version 8.0 (Research Triangle Institute, Research Triangle Park, NC).
The main characteristics of the 1999-2000 NHANES survey participants are provided in Table 2. The women’s mean age was slightly higher than the men’s (44.6 vs 43.3 years). Approximately one third of US adults were overweight and obese, respectively. More than one fifth of the population was current smokers and ever smokers, respectively, and more men than women were smokers. Eighty-two percent of men and 62% of women reported consuming at least 12 drinks of alcoholic beverages per year.
The mean SBP and DBP by sex, ethnicity, age, and education levels are presented in Table 3 and the Figure. Black men and women had higher SBP than the other ethnic groups, and black women had higher DBP than the other ethnic groups. People with higher education appeared to have a lower SBP. Overweight and obese men and women had higher SBP and DBP than their nonoverweight counterparts.
Table 4 presents a high prevalence of prehypertension and hypertension. Approximately 60% of American adults (67% of men and 50% of women) had prehypertension or hypertension and 27% had hypertension. The prevalence of prehypertension was higher among men than women (40% vs 23%), but the prevalence of hypertension was similar, which may be related to a lower awareness of hypertension among men. Furthermore, considerable ethnic-, age-, and education-related differences were observed. Blacks had the highest rate, whereas Mexican Americans had the lowest, and rates increased considerably with age. For example, the prevalence of prehypertension and hypertension increased from 40% among people aged 18 to 39 years to 88% among those 60 years and older; for hypertension, these rates went from 8% to 65%, respectively. Higher-education groups were not as affected by this problem, and the differences were more remarkable in women than in men. The prevalence of prehypertension and hypertension ranged from 54% among people with more than a high school education to 65% among people with less than a high school education, whereas the prevalence of hypertension ranged from 23% to 33%, respectively (25% to 28% in men and 20% to 38% in women). Obesity is an important predictor of prehypertension and hypertension. Approximately 60% of overweight individuals and three fourths (75.5%) of obese participants had prehypertension or prehypertension, whereas the prevalence was only 47% in the nonoverweight group. The difference in the prevalence of hypertension among the 3 groups was more remarkable (27.8%, 42.5%, and 15.3%, respectively). The patterns were similar in men and women, although men had higher provenance than women.
The patterns by sociodemographic characteristics are presented in Table 5, Table 6, Table 7, through Table 8. We first studied the patterns among hypertensive patients (Table 5) and then among both prehypertensive and hypertensive patients (Table 6). Both analyses suggest a serious problem of low awareness and inadequate management of hypertension. Only 69% of hypertensive patients (65% in men vs 72% in women, P = .056) and 38% of prehypertensive and hypertensive patients (31% in men vs 45% in women, P<.001) were aware of their hypertension. Slightly fewer people had been told by physicians or other health care professionals to take medication or make lifestyle modifications to control for hypertension (66% among hypertensive patients vs 35% among prehypertensive and hypertensive patients), and 64% of the hypertensive patients followed the advice. Only 31% of all hypertensive patients, 45% of those hypertensive patients who were aware of their hypertension, and 54% of all those who had taken antihypertensive medication had their hypertension controlled (SBP<140 mm Hg and DBP <90 mm Hg).
As presented in Table 5, our analyses reveal some significant differences across sociodemographic groups in the awareness, management, and treatment of hypertension among hypertensive patients. Men were less likely to take antihypertensive medication than women (53% vs 62%). Compared with white and black hypertensive patients, Mexican Americans were less likely to be aware of their hypertension, to be told to take medication or adopt lifestyle modifications to control for hypertension, or to follow the advice once given. Similarly, all these rates were lower in the younger group (18-39 years) than in the older groups. None of the differences across education groups were significant except for control of hypertension. Overweight and obese hypertensive patients had better awareness, management, treatment, and control of hypertension than patients who were not overweight.
Similar patterns were observed among prehypertensive and hypertensive patients, although more differences were statistically significant (Table 6). Women and older people were more likely to be aware of hypertension, receive instructions for controlling the disease, and follow the advice than their counterparts. Mexican Americans had the worst outcomes, whereas blacks had the best indicators in all these measures. There is a clear trend of increased awareness and better management of hypertension with age.
We also examined the management of hypertension among Americans who were already aware of their condition (Table 7). Approximately 7% of these hypertensive patients did not adopt any lifestyle modifications and 15% did not take antihypertensive medications. The problem was much worse among Mexican Americans (13% and 31%, respectively) and young patients (18% and 49%, respectively). There was no significant difference by body weight status.
Table 8 gives the control of hypertension among patients who took antihypertensive medications. Approximately half (54%) of these patients had their hypertension controlled. Men and participants with higher education fared better than their counterparts. Mexican American men fared the worst among all sex-ethnicity groups. There was no significant difference across different body weight groups.
This study indicates that elevated BP is a serious problem in the United States according to the new JNC guidelines. Approximately 60% of American adults had prehypertension or hypertension, and some population groups, such as African Americans, senior citizens, and low-socioeconomic-status groups, are disproportionately affected. Furthermore, low awareness and inadequate management of hypertension among hypertensive patients deserve great attention. Approximately one third of hypertensive patients were not aware of their hypertension status. Only less than two thirds of the hypertensive patients had adopted lifestyle modifications or taken prescriptions to control their BP, and only 31% had their hypertension controlled.
Consistent with other studies, our analysis shows that obesity is an important predictor of elevated BP: 75.5% of obese individuals had prehypertension or hypertension and 42.5% had hypertension, whereas these figures were only 47.0% and 15.3% among nonoverweight individuals, respectively. Of interest, we found that overweight and obese hypertensive patients had better awareness, management, treatment, and control of hypertension than nonoverweight patients. This is particularly interesting because overweight and obese hypertensive patients were more likely to be diagnosed as having hypertension and receive related lifestyle modification recommendations and medications from their physicians or other health care professionals than nonoverweight patients. There was no significant difference in the management, treatment, and control of hypertension between the overweight or obese and nonoverweight hypertensive patient groups once they were aware of their hypertension.
Another important finding of this study is that the prevalence of hypertension has increased considerably in the United States during the past decade (by 7 percentage points—from 20% to 27%), although previous data show that the prevalence had declined in the 1970s and 1980s. Based on the NHANES I (1971-1974) and NHANES III phase 1 data (1988-1991), Burt et al3 reported that the prevalence of hypertension decreased from 36.3% to 20.4% during the survey period. Using the NHANES III data collected in 1988-1994, Joffres et al4 studied 15 326 US participants (aged 18-74 years) and reported a hypertension prevalence of 20.1%. Although a number of factors might have contributed to the rise, the increase in obesity, in particular, seems to be the major driving force. Recently, based on the NHANES survey data, Flegal et al11 reported that the prevalence of obesity (BMI, ≥30) has increased by 8 percentage points, from 23% in 1988-1994 to 31% in 1999-2000. During this period, the prevalence of overweight (BMI, ≥25) also increased from 56% to 65%. A large number of previous studies have shown that obesity is an important risk factor for hypertension, and there is a strong association between BMI and BP.12 Together, these findings suggest that the potential health benefits from obesity prevention are of considerable public health importance.
It is worth noting that the age differences between the US population included in our study and those of previous NHANES surveys and studies may also have influenced the trends we observed, but our analysis suggests that these differences only explain a small part of the increase. It is possible that the aging of the US population and our inclusion of participants older than 74 years may have resulted in a higher prevalence. Although examination of this trend is not a focus of this study, we reanalyzed the NHANES 1999-2000 data with different age restrictions: (1) the prevalence of hypertension for people aged 20 to 74 years was 25%, and (2) the prevalence among people 20 years and older was 28%, but the age-adjusted prevalence based on the 1990 US population age distribution is 30%, which is 10 percentage points higher than the prevalence (20%) in 1988-1994. The age influence needs to be considered when one compares findings among studies based on different surveys. Other factors, such as changes in people’s lifestyles and the population composition, have probably also affected the trends. Further studies are needed to understand the underlying causes of the trends.
In general, no improvement was observed in people’s awareness, treatment, and control of hypertension between NHANES III and NHANES 1999-2000, although there was a remarkable improvement in the 1980s between NHANES II and NHANES III.3,13 The proportion of hypertensive patients who were aware of their hypertension was 51% (42% in men vs 63% in women) in 1976-1980, 73% (66% in men vs 81% in women) in 1988-1991, and 69% (65% in men vs 72% in women) in 1999-2000. For hypertension treatment, thesefigures were 31% (21% in men vs 43% in women) in 1976-1980, 55% (46% in men vs 65% in women) in 1988-1991, and 58% (53% in men vs 62% in women) in 1999-2000. Regarding the control of hypertension, the 1999-2000 NHANES data show that only 31% (32% in men vs 30% in women) of hypertensive patients had their BP controlled to lower than 140/90 mm Hg, whereas the figure was 29% (22% in men vs 38% in women) in NHANES III.3,13 An improvement was seen among men, but the situation became worse among women.
The relationship between BP and risk of cardiovascular disease events is continuous and consistent.1,14,15 For individuals aged 40 to 70 years, the risk of cardiovascular disease doubles for each increment of20 mm Hg in SBP or 10 mm Hg in DBP across the BP range, starting at 115/75 mm Hg.15 Therefore, preventing prehypertension and hypertension and controlling BP at the target level among hypertensive patients are important public health goals. Patients, clinicians, and other related parties need to work together to achieve the Healthy People 2010 goals for fighting hypertension, which include reducing the prevalence to 16%, increasing to 95% the proportion of hypertensive patients who are taking action (eg, lifestyle modifications) to help control their BP, and increasing the proportion of hypertensive patients whose BP is under control to 50%.16 Our findings with the recent NHANES data indicate that Americans are facing considerable challenges in achieving these goals. As recently commented by several researchers,17- 20 people should not be surprised to see the low levels of awareness, treatment, and control of hypertension considering the many existing barriers, and Americans can do a better job in fighting the hypertension epidemic.
The JNC 7 report recommends lifestyle modifications for all patients with prehypertension (SBP ≥120 mm Hg or DBP ≥80 mm Hg), including losing weight, increasing physical activity,adopting the DASH (Dietary Approaches to Stop Hypertension)eating plan, and moderating alcohol consumption. Patients who reported adoption of these lifestyle modifications were found to be 6 times (odds ratio, 6.0; 95% confidence interval, 4.2-8.6) more likely to have their hypertension controlled.6 These lifestyle modifications have many other benefits in addition to helping control BP; however, only if patients are provided with these recommendations and guidelines by their physicians and other health care professionals and only when they are properly motivated can they overcome the barriers in daily life to establishing and maintaining a healthy lifestyle. Both the general public and health professionals need to be better informed about the new guidelines for the success of the campaign. For prevention to be successful, it is especially important for there to be significant societal changes, including stronger cooperation among national, state, and local government agencies, health organizations, and the food industry.20
In conclusion, this study shows that the United States is facing a serious challenge in the prevention and management of prehypertension and hypertension, since according to the new JNC guidelines 60% of the US population is affected by the condition. However, awareness and control of hypertension in the United States remain poor. Our findings highlight the seriousness of the problem and the importance of promoting appropriate lifestyle modifications. The new guidelines should serve as a wake-up call to reinvigorate the efforts of the general public, clinicians, and public health care professionals to prevent and control HBP in the United States.
Correspondence: Youfa Wang, MD, PhD, Department of Human Nutrition, Mail Code 517, University of Illinois at Chicago, 1919 W Taylor St, Chicago, IL 60612 (firstname.lastname@example.org).
Accepted for Publication: December 16, 2003.
Financial Interest: None.
Funding/Support:This study was supported by the University of Illinois at Chicago, and Dr Y. Wang was also supported by National Institutes of Health grant 1 R01 DK63383-01.