Trends in the hospitalization of ischemic stroke in the United States, 1998-2007

Background The late 1990s/early 2000s was a time of change in both the prevention and acute care of ischemic stroke, with primary prevention driven by increased utilization of antihypertensive, antiplatelet, anticoagulation, and lipid-lowering agents. Aim To examine whether ischemic stroke hospitalization rates and outcomes in the United States have changed. Method We retrospectively identified 894 169 hospitalizations with a primary diagnosis of ischemic stroke from 1 January 1998 through to 31 December 2007 in the Nationwide Inpatient Sample, the largest all-payer healthcare database in the United States. Annual, national case estimates were combined with US Census data to derive age-adjusted and age-specific population hospitalization rates. Temporal trends were tested using linear regression. Results From 1998 through 2007, there were an estimated 4 382 336 ischemic stroke hospitalizations in the United States. Overall, the age-adjusted rate of ischemic stroke hospitalization decreased from 184 to 128 per 100 000 (P < 0.0001). Age-specific rates decreased among those 55+ years old (P < 0.0001), but increased among those 25-34 and 35-44 years old (P < 0.001 and P < 0.0001, respectively). Rates among those < 25 and 45-54 years old were unchanged. In-hospital mortality decreased from 7.0% (standard error 0.1) to 5.4% (standard error 0.1) (P < 0.0001). Case proportion at the highest quintile of hospitals by annual caseload increased from 54.0% (standard error 2.1) to 61.8% (standard error 2.0) (P < 0.0001). Mean adjusted hospitalization costs increased from $9273 (standard deviation 199) to $10 524 (standard deviation 77) (P < 0.0001). Conclusion In 1998 through to 2007, the overall rate of ischemic stroke hospitalization in the United States decreased. However, rates among young adults increased. In-hospital mortality rates decreased over the study period.