Improved survival of stroke patients during the 1980s: The Minnesota stroke survey

Background and Purpose: The underlying reasons for the decline in stroke mortality in the United States are not well understood and have been the subject of ongoing debate. This study was undertaken to determine whether survival of hospitalized stroke patients has changed during the 1980s, thereby contributing to the decline in stroke mortality during that period. Methods: For the years 1980, 1985, and 1990, we obtained listings of discharge diagnoses from hospitals in the Minneapolis-St Paul metropolitan area and identified all hospitalizations with a discharge diagnosis code of acute cerebrovascular disease according to the International Classification of Diseases, 9th Revision. A 50% random sample of men and women aged 30 to 74 years was selected in each survey for detailed medical record abstraction. Standardized sets of criteria for stroke were then used to validate acute stroke events throughout the 1980s. Each of the three period cohorts of hospitalized stroke patients (1980, 1985, and 1990) was followed for at least 2 years for all-cause mortality end point. Results: A total of 1853 patients met minimal criteria for acute stroke: 564 patients in 1980, 598 patients in 1985, and 691 patients in 1990. Controlling for age, the odds of death within 2 years after stroke were approximately 40% lower in 1990 than in 1980. The relative odds of 2-year death in 1990 (versus 1980) were 0.65 (95% confidence interval, 0.47 to 0.89) and 0.60 (95% confidence interval, 0.42 to 0.85) for men and women, respectively. The improved survival was evident in the short term (28 days) as well as for stroke patients who survived that period. Analysis according to stroke subtype revealed that improved survival of ischemic stroke and specifically of stroke with no apparent cardioembolic source largely accounted for the overall trend. The prognosis of stroke patients who were admitted in a comatose state has not changed during that decade. Conclusions: Despite the absence of any clear major advances in acute stroke therapy, survival of stroke patients substantially improved during the 1980s. The underlying reasons for this unexpected yet remarkable trend remain uncertain but may include improved supportive and rehabilitative care of stroke victims as well as a change in the natural history of the disease.