Oct. 11, 2012— -- Stroke may be shifting from a disease of the elderly to a midlife health concern, according to a new study.
The study of roughly 1.3 million American adults found the rate of first stroke among patients age 20 to 54 jumped from 12.9 percent in 1993 and 1994 to 18.6 percent in 2005, according to study author Dr. Brett Kissela of the University of Cincinnati in Ohio, and colleagues.
Those findings were published online in the journal Neurology.
Kissela and colleagues said the uptick in "young" stroke over that decade may reflect a changing prevalence of stroke risk factors, including hypertension, diabetes, and smoking in younger patients.
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Over the course of the study, stroke incidence declined overall in white patients ages 55 and older and in black patients ages 65 and older. But these declines were offset by increases in black and white patient first stroke incidence among patients age 20 to 44 and age 20 to 54.
In the entire group -- ages 20 to 54 -- incidence among blacks went from 83 to 128 per 100,000 and for whites the incidence almost doubled from 26 per 100,000 to 48 per 100,000 from 1993/1994 to 2005.
The majority of strokes in the younger population were caused by infarcts. The proportion of first strokes caused by infarcts rose over the study period from 56.8 percent to 65.7 percent in patients ages 20 to 44, but that increase was not statistically significant.
The authors said that among patients in this age group hypertension and smoking increased during the decade studied, but there was a slight decrease in obesity from 1999, the first year this measure was obtained, to 2005 -- from 48.1 percent of the population to 43.8 percent.
Compared with data from the National Health and Nutrition Examination Survey in 1999/2000 and 2005/2006 among patients in same age range, prevalence rates were higher for all leading risk factors, though high cholesterol was more prevalent nationally.
The authors noted that -- as would be expected -- "the prevalence of stroke risk factors, including hypertension, diabetes, [coronary heart disease] and current smoking are all elevated in the younger stroke population compared with the population survey."
They added that the reasons for the incidence trends were not clear, but that it was "possible that the trend toward younger stroke is related to changing risk factor prevalence," which did not match data seen in NHANES.
In an accompanying editorial, the "progressive adoption of MRI as a diagnostic tool during the study period" may account for the increased count of incident strokes among younger populations, wrote Drs. Mitchell Elkind and Sally Sultan, both of Columbia University in New York, N.Y.
The editorialists also noted that stroke mechanisms differ in the younger population, where "obesity and diabetes are on the rise in young adults and are more common in black patients and other race/ethnicity groups compared with white patients."
The authors said the study was limited by methodologic drift, incomplete case ascertainment, and self-reported prevalence data, as well as the observational design.