Stroke rates during the 1980s. The Minnesota Stroke Survey

Abstract

Background and purpose: The decline in stroke mortality it the United States may have resulted from declining incidence improved survival of stroke patients, or both. We previously reported that stroke patients who were 30 to 74 years old and were treated in Minneapolis/St Paul hospitals in 1990 survived longer than did their counterparts in 1980. In the present study, we examined trends in the rate of hospitalized stroke in Minneapolis/ St Paul between 1980 and 1990.

Methods: For 1980, 1985, and 1990, we obtained lists of discharge codes (International Classification of Diseases, 9th revision) from Minneapolis/St Paul hospitals, identified hospitalizations for acute cerebrovascular disease, and randomly selected 50% of the cases for medical record abstraction. We counted stroke events in five different ways, which were based on discharge codes as well as diagnostic criteria, and computed age adjusted stroke rates for each year. Stroke mortality in the population was computed for 1960 through 1994.

Results: Among men, all five measures of hospitalized stroke attack rate indicated a decline between 1980 and 1985, which ranged from 5% to > 20%. Among women, there was a sharp contrast between trends that relied on discharge codes and trends that relied on diagnostic criteria: the former indicated a decline (4% to 19%), whereas the latter indicated some increase. For the second half of the 1980s, most measures of stroke attack rate in men, all measures of stroke attack rate in women, and measures of stroke incidence in both sexes did not indicate a decline in stroke occurrence in the population. Mortality from stroke among 30- to 74-year-old residents of Minneapolis/St Paul, which declined rapidly during the 1970s and early 1980s, declined slowly, if at all, during the second half of the 1980s and early 1990s.

Conclusions: The incidence of stroke may have declined among 30- to 74-year-old residents of Minneapolis/St Paul in the early 1980s. However, we found little indication of such a trend between 1985 and 1990, a period of slow decline or no decline in stroke mortality in that population.