Hypertension Doubles Risk of Stroke, but "Prehypertension" Is Not a Stroke Risk Factor
Hypertension is a major risk factor for all types of stroke, and control of hypertension is known to markedly reduce the risk of stroke. Several studies presented at the American Stroke Association's 29th International Stroke Conference addressed the magnitude of stroke risk associated with hypertension, and in people who are at increased risk of progression to high blood pressure (prehypertensive).
Researchers from Boston University School of Medicine (Boston, Massachusetts) announced that men and women with normal blood pressure as defined by JNC 7 criteria (< 120/80 mm Hg) have only half the lifetime risk of stroke compared with people with hypertension. Sudha Seshadri, MD, and colleagues based their calculations on data from 4883 participants in the original Framingham Heart Study cohort who survived stroke-free to age 55 years. These participants were then followed at 2-year intervals for up to 40 years or until they had a first stroke, developed Alzheimer's disease, or died. During this time, a total of 859 strokes occurred, 86% of which were ischemic. Women aged 55 years or older had a lifetime stroke risk of 21% compared with 17% in men of the same age. These risks remained relatively stable until age 85 years. The risk of stroke increased with increasing baseline blood pressure in men and women.
According to the results of an analysis of participants in the First National Health and Nutrition Examination Survey (NHANES I) or the Epidemiologic Follow-up Study (NHEFS), people who were defined as having "prehypertension" according to the new JNC 7 category for blood pressures within the range 120-139/80-90 mm Hg do not appear to be at increased risk of stroke or myocardial infarction (MI). Yousef Mohammad, MD (Ohio State University, Columbus) and investigators at the University of Medicine and Dentistry of New Jersey (Newark) and the National Institute of Neurological Disease and Stroke (Bethesda, Maryland), evaluated the association of prehypertension and hypertension (≥140/90 mm Hg) with the incidence of ischemic stroke (IS), intracerebral hemorrhage (ICH), and MI in 6081 adults. During a mean follow-up period of 16 years, 267 strokes and 890 MIs were recorded in these subjects. After adjustment for differences in age, gender, smoking, serum cholesterol, diabetes mellitus, and body mass index, the risk of cardiovascular disease was found to be increased by 50% in people with hypertension, but was not increased in people who were prehypertensive. The risk of IS and MI was almost doubled in people with hypertension, but again, not increased in prehypertensive individuals. Dr Mohammad and his colleagues called for more studies to identify "the anticipated benefits of identifying and intervening in persons with prehypertension." The new "prehypertension" category of JNC 7 has been widely criticized as having created a new "disease," with consequent anxiety for the public.
Medscape Cardiology. 2004;8(1) © 2004 Medscape
Cite this: Hypertension, But not "Prehypertension," Increases Stroke Risk -- and Should Combination Therapy Include a Calcium Antagonist? - Medscape - Mar 17, 2004.