SAN ANTONIO — Not only is the average age of stroke patients getting significantly younger, but the proportion of young stroke patients—those younger than 45 years—is going up significantly, according to a population-based study of more than 1 million people over a 12-year period.
The average age at the time of stroke dropped from 71.3 years in 1993-1994 to 70.9 years in 1999 to 68.4 years in 2005, Dr. Brett Kissela reported at the annual International Stroke Conference. Over the same period, the percentage of stroke patients younger than 45 years went up, from 4.5% in 1993-1994 to 5.5% in 1999 and to 7.3% in 2005. (See table for rates.)
“In the converse, in the oldest age groups … there were statistically significant declines in incidence rates,” said Dr. Kissela, professor of neurology at the University of Cincinnati.
Dr. Kissela and his coinvestigators examined data from the Greater Cincinnati/Northern Kentucky stroke study, which includes 1.3 million people in five counties. The region is representative of the United States in terms of age, median income, educational level, and percentage of blacks in the population.
The investigators identified patients retrospectively by using ICD-9 discharge diagnosis codes and symptom-based screening of admission logs. Potential stroke cases were identified in local hospitals, hospital-based clinics, or coroner's offices. In addition, there was a sampling of nursing homes and physician offices.
The medical record abstract for each potential case was reviewed by a study physician to determine whether to include it as a stroke, identify the subtype of stroke, and review imaging if necessary and available.
The same clinical case definition was used for comparisons across study periods. Stroke was defined as a focal neurologic deficit referable to a vascular territory and lasting longer than 24 hours. For the incidence rates, the numerator was the number of incident cases and the denominator was the at-risk population. The at-risk population was calculated using U.S. Census population data for 1980, 1990, and 2000.
There were 1,907 strokes in 1993-1994, 1,955 in 1999, and 1,888 in 2005. In each period, more than half (55%-58%) of the individuals who had a stroke were women. Blacks accounted for 18%-20% of the population, Dr. Kissela said at the conference, sponsored by the American Heart Association.
One possible explanation for increasing strokes among younger age groups might be an increase in hemorrhagic strokes. However, when the researchers looked at this, they found that ischemic strokes outnumbered hemorrhagic strokes (intracranial and subarachnoid hemorrhage) in those aged younger than 45 years in all three time periods, and even seemed to increase in 2005.
They looked at the prevalence of risk factors using data from population-based telephone surveys of the region that were linked to the three study periods and were performed in 1995, 2000, and 2001.
Among those aged 20-44, both diabetes and coronary heart disease significantly increased between 1995 and 2005. The prevalence of diabetes increased from 0% to 5% and CHD increased from 0.4% to 7%. There were similar trends for hypertension and high cholesterol, although these were not significant. In contrast, there were no significant changes in these risk factors among those aged 45-54 years.
The study is funded by the National Institute of Neurological Disorders and Stroke. Dr. Kissela reported that he and his coinvestigators have no relevant financial relationships.
Ischemic strokes outnumbered hemorrhagic strokes in those aged younger than 45.
Source DR. KISSELA
Source Elsevier Global Medical News