Epidemiology of Uncontrolled Hypertension in the United States
Authors: Thomas J. Wang, Ramachandran S. Vasan
Journal: Circulation (2005)

ypertension is a powerful risk factor for fatal and nonfatal cardiovascular disease events.Data from observational studies indicate that this risk is continuous, without evidence of a threshold, down to blood pressures as low as 115/75 mm Hg. 1 Randomized controlled trials have convincingly shown that treatment of hypertension reduces the risk of stroke, coronary heart disease, congestive heart failure, and mortality. 2,3Because hypertension currently affects 1 in 4 American adults (Ϸ65 million people in 1999 to 2000) 4 and may affect Ͼ90% of individuals during their lifetimes, 5 adequate control of blood pressure is of enormous public health importance.However, recent studies indicate that as many as two thirds of those with hypertension in the United States are either untreated or undertreated. 6Studies based on national data and community cohorts have shed light on the reasons underlying this poor control, but several questions remain unanswered.In this article, we review contemporary data on the epidemiology of uncontrolled hypertension in the United States by ( 1) defining what constitutes "controlled hypertension"; (2) describing the current magnitude of the problem, including temporal trends; (3) summarizing the public health consequences of uncontrolled hypertension; (4) examining the clinical correlates of uncontrolled hypertension and appraising the patient-and physician-related factors related to poor control of blood pressure; and (5) identifying future research directions, including potential interventions to address this problem.In this article, "uncontrolled hypertension" signifies blood pressure that is inadequately treated rather than blood pressure that is resistant to treatment, as might be observed with secondary causes of hypertension such as renal artery stenosis. Definition: What Is Optimal BloodPressure Control?The definition of high blood pressure has changed over time and differs between guidelines proposed by expert bodies.Variation in the definition of hypertension influences the number of people classified as having uncontrolled hypertension 7 and may contribute to uncertainty among clinicians (Table 1). 8The 1977 report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC) regarded a blood pressure Ն160/ 95 mm Hg as elevated, although treatment recommendations were based primarily on the diastolic blood pressure. 9The 1980 JNC report defined hypertension based on a diastolic blood pressure threshold alone (90 mm Hg). 10 In 1984, this definition was changed again, to a blood pressure Ն140/ 90 mm Hg. 11 In JNC VI (1997), a lower threshold of 130/85 mm Hg was recommended for individuals with diabetes mellitus. 12JNC VII lowered this target for individuals with diabetes or chronic kidney disease, to 130/80 mm Hg, 3 bringing this threshold in agreement with recommendations of the American Diabetes Association and the National Kidney Foundation. 13,14However, the National Committee for Quality Assurance (NCQA), an organization that issues periodic "report cards" for managed care organizations, continues to use a cut point of 140/90 mm Hg in both diabetic and nondiabetic patients. 15 Individuals with evidence of target organ damage such as left ventricular hypertrophy or who have experienced clinical sequelae such as heart failure are at particularly high risk of cardiovascular events, and use of lower blood pressure thresholds for these individuals was endorsed by JNC VI. 12 The European Society of Hypertension/European Society of Cardiology guidelines also recommend that treatment thresholds account for baseline cardiovascular risk, 16 similar to the approach based on absolute risk contained in the National Cholesterol Education Program (NCEP) guidelines. 17However, in an effort to simplify treatment guidelines, the JNC VII report recommends use of an alternate blood pressure threshold only for patients with diabetes or chronic kidney disease. 3 Magnitude of the ProblemData on the prevalence of controlled and uncontrolled hypertension are available from national cross-sectional surveys, epidemiological investigations, community studies, health maintenance organizations, and reports of physician office practices (Table 2). 6,18 -42 From the Framingham Heart Study, Framingham, Mass (T.