Cause of Stroke Recurrence Is Multifactorial

BACKGROUND AND PURPOSE: This article examines stroke recurrence and whether the subtype of the initial stroke influences the risk and subtypes of further strokes. The proportion of recurrences attributable to conventional risk factors is quantified. METHODS: From January 1995 to August 2000, all first-in-a-lifetime strokes (n=1626) were identified and prospectively followed up in a defined multiethnic inner city population of 234 533. Twelve overlapping referral sources and face-to-face follow-up at 3 months and 1 and 3 years were used to attain complete registration of stroke recurrence. Index and recurrent stroke were classified according to the Oxford Community Stroke Project classification. RESULTS: In 2744 person-years of follow-up, 153 recurrences were observed. At 5 years, the cumulative risk of first stroke recurrence was 16.6% (95% CI, 13.5 to 20.4), and the combined risk of death or stroke recurrence was 65.3% (95% CI, 61.9 to 68.6). Ethnicity and subtype of index stroke were not associated with stroke recurrence. A change in subtype between index and recurrent stroke occurred in 45.5% (95% CI, 35.8 to 55.2) of cases and was most frequent among index lacunar strokes and primary intracerebral hemorrhages. In multivariable analyses, diabetes mellitus and atrial fibrillation were associated with both stroke recurrence and recurrence-free survival. In the stroke population, 9.1% (95% CI, -2.0 to 20.2) of recurrences were attributable to diabetes and 4.9% (95% CI, -7.3 to 17.2) to atrial fibrillation during the first year after the index stroke. CONCLUSIONS: The cause of stroke recurrence is multifactorial, and the subtypes of index and recurrent strokes are often not identical. Most recurrences remain unexplained by conventional risk factors.