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Declining Risk and Incidence of Clinical Stroke

Age-adjusted incidence of first stroke has decreased during the past 50 years.

Stroke is the third leading cause of death and the number-one etiology of long-term neurologic disability in the U.S. Researchers prospectively examined the Framingham Study cohorts during three intervals (1950–1977, 1978–1989, and 1990–2004) to ascertain trends in stroke incidence, severity, 30-day mortality, and risk. The authors defined clinical stroke as "rapidly developing signs of focal neurologic disturbance of presumed vascular etiology, lasting more than 24 hours."

The age-adjusted incidence of first stroke per 1000 person-years decreased in each of the three intervals both in men (7.6, 6.2, and 5.3, respectively) and in women (6.2, 5.8, and 5.1). The 10-year risk at age 65 decreased significantly in men (from 19.5% to 14.5%) but not in women (from 18.0% to 16.1%). Similarly, 30-day mortality decreased significantly in men (from 23% to 14%) but not in women (from 21% to 20%). Assessment of risk factors at age 65 demonstrated significant reductions in mean systolic blood pressure, total cholesterol, prevalence of hypertension, and prevalence of current smoking as well as an increase in the proportion of persons receiving antihypertensive treatment. However, the prevalence of atrial fibrillation in men and the mean body-mass index in both sexes increased. Overall, the Framingham Stroke Risk Profile, a validated instrument, improved significantly for both men and women. The proportion of strokes that were moderate or severe did not change significantly in men or women.

Comment: The good news is that the annual incidence of clinical stroke has declined during the past 50-plus years for men and women, as has the 10-year risk for stroke for people aged 65. The bad news is that stroke severity has not declined and that 30-day mortality has dropped only in men. The latter finding could be due to older age at stroke onset and greater stroke severity in women. The need for primary prevention continues.

— John A. Marx, MD, FAAEM, FACEP

Published in Journal Watch Emergency Medicine February 2, 2007

Citation(s):

Carandang R et al. Trends in incidence, lifetime risk, severity, and 30-day mortality of stroke over the past 50 years. JAMA 2006 Dec 27; 296:2939-46.

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