Abstract 1207: Recent Trends in Stroke Hospitalization, 1998–2007
While age-adjusted stroke mortality has declined in recent decades in the U.S., less is known about trends in stroke hospitalization, which may provide important insight into the effectiveness of primary and secondary prevention efforts. We examined trends in stroke from 1998 –2007 among adults aged ≥35 years in a large and diverse integrated health care delivery system with over 3.2 million members. Hospitalized stroke was identified by ICD-9 dismissal diagnosis codes of 430 – 438. Age-standardized attack rates were calculated for each year by the direct method using the overall study population as the reference. Trends were analyzed by Poisson regression. Attack rates were calculated separately for ischemic strokes (ICD-9 433– 434 and 436), subarachnoid hemorrhage (SAH) (ICD-9 430) and intracerebral hemorrhage (ICH) (ICD-9 431– 432). Between 1998 –2007, there were 68,788 hospitalizations for stroke (44,840 ischemic, 8,535 ICH, 2,479 SAH), of which 50% occurred in men and 38% in persons aged ≥75 years. The attack rate of stroke hospitalization was relatively stable over the 10 year period. In 1998, the rate (95% CI) was 45.6 (45.2, 45.9) per 10,000 persons and in 2007 the rate was 47.1 (46.7, 47.4) per 10,000 persons (p for trend=0.80). Annual age-adjusted rates of ischemic stroke and ICH were consistently higher among men than women but rates of SAH were lower among men than women. For ischemic stroke, hospitalization rates decreased an average of 1.2% per year (95% CI, −1.8, −0.6%) among men and 0.8% per year (−2.0, 0.3%) among women. SAH hospitalization rates were stable, whereas the hospitalization rates for ICH decreased an average of 1.9% per year (95% CI, −3.2, −0.5%), among men and 1.0% per year (−3.0, 1.0%) among women. Significant declines in average annual percent change in ischemic stroke were observed among Whites and Asians and (−1.3% and −1.1%, respectively; both p<0.05) and in ICH among Whites only (−1.7%; p=0.02). These data, demonstrating race and sex differences in decline of ischemic stroke and ICH hospitalizations since 1998, suggest that all segments of the population have not uniformly benefited from prevention efforts. It will be important to explore the contribution of individual level factors on these trends and their role in stroke mortality.