Abstract 139: Trends in Ischemic Stroke Subtype Over a 17-Year Period

Abstract

Introduction: Overall US stroke incidence rates have declined. Prior analysis of the Cincinnati region has demonstrated more thorough diagnostic workups coinciding with decreased proportion of cryptogenic and increased proportion of cardioembolic strokes over time in those patients presenting to the ED. We now examine trends in population-based incidence rates of stroke subtypes. Methods: Within the Greater Cincinnati/Northern Kentucky catchment area of 1.3 million, all strokes were ascertained between July 1993 and June 1994 and in 1999, 2005 and 2010. Incidence rates per 100,000, age-, race- and sex-adjusted to the 2000 US population, and associated 95% confidence intervals were calculated. Changes in stroke-subtype proportions over time were examined using a general linear model. Results: There were a total of 6859 incident ischemic strokes (1709 in 1993/94, 1778 in 1999, 1681 in 2005, and 1691 in 2010; age ≥20 years), of which 1290 (18.8%) were black and 3846 (56.1%) female. The Table shows subtype-adjusted incident rates by study period. Incidence rates of both small- and large-vessel etiology showed no significant change over time. Incidence rates of both cardioembolic and other known etiology increased significantly over time, whereas incidence rates of unknown subtype decreased significantly. Conclusions: In our large, biracial population-based cohort, while overall stroke incidence rates have been stable or declining over the last 17 years, trends for individual stroke subtypes have varied. Consistent with our prior analyses, more strokes have been attributed to cardioembolic etiology, whereas strokes attributable to small-vessel and large-vessel etiology have remained stable. The increase in cardioembolic strokes may be due to age and/or prolonged cardiac monitoring. Future analysis of age-adjusted rates for atrial fibrillation over time is warranted.