The treatment of hypertension is the most common reason for office visits of non-pregnant adults to physicians in the United States and for use of prescription drugs . The national health and nutrition examination survey (NHANES) conducted from 2005 through 2008 estimated that approximately 29 to 31 percent of adults in the United States have hypertension . This translates into 58 to 65 million hypertensives in the adult population in the United States .
The number of patients with hypertension is likely to grow as the population ages, since either isolated systolic hypertension or combined systolic and diastolic hypertension occurs in the majority of persons older than 65 years (figure 1) . The rising incidence of obesity will also increase the number of hypertensive individuals . (See "Treatment of hypertension in the elderly patient, particularly isolated systolic hypertension".)
Despite the prevalence of hypertension and its associated complications, control of the disease is far from adequate. Data from the 2005-2008 NHANES survey show that only 46 to 51 percent of persons with hypertension have their blood pressure under control, defined as a level below 140/90 mmHg (table 1) .
There are numerous potential reasons for low rates of blood pressure control, including poor access to health care and medications and lack of adherence with long-term therapy for a condition that is usually asymptomatic . The latter may be particularly true when the therapy may interfere with the patient's quality of life and when its immediate benefits may not be obvious to the patient. Thus, hypertension will likely remain the most common risk factor for heart attack and stroke . (See "Patient adherence and the treatment of hypertension".)
This topic provides a broad overview of the definitions, pathogenesis, complications, diagnosis, evaluation, and management of hypertension. Detailed discussions of all of these issues are found separately. The reader is directed, when necessary, to more detailed discussions of these issues in other topics.