Declining US Stroke Hospitalization since 1997: National Hospital Discharge Survey, 1988–2004

Abstract

Background and Purpose: While age-adjusted stroke mortality in the United States has declined consistently during the last century, trends in stroke incidence and hospitalization are less known. This study examines trends in stroke hospitalization from 1988 to 2004. Methods: Stroke hospitalizations were estimated from the annual National Hospital Discharge Survey, 1988–2004. Stroke was defined as a first-listed diagnosis of ICD-9-CM (International Classification of Diseases, 9th Revision, Clinical Modification) code 430–434 or 436–438. Trends in hospitalization rates were compared for groups defined by selected patient characteristics. Results: Stroke hospitalizations totaled 603,000 in 1988, peaked at 833,000 in 1997, then declined to 726,000 in 2004, a figure still higher than in 1988. Age-adjusted stroke hospitalization rates for men (per 100,000 population) increased from 287 in 1988 to 352 in 1997, but declined to 265 in 2004, and for women, rates were 252, 293 and 223 in the corresponding years. The majority of stroke hospitalizations in 2004 occurred at ages ≧65 years (69% in men and 78% in women). Decline in rates after 1997 occurred at ages 65–74 and ≧75 years. In 2004, 64% of strokes were classified as ischemic, 16% as hemorrhagic and 16% as ill-defined. Decline in hospitalization rates after 1997 were observed for ischemic and ill-defined, but not for hemorrhagic stroke. Between 1988 and 2004, the reporting of hypertension, diabetes and coronary heart disease as secondary diagnoses among stroke hospitalizations increased. Conclusions: Decline in stroke hospitalizations since 1997 was observed among men and women >65 years, who suffered ischemic or ill-defined stroke. Although long-term observation is needed to confirm this finding, the decline in stroke hospitalizations after 1997 suggests treatment of hypertension may have resulted in stroke prevention.