Trends in survival of hospitalized stroke patients between 1970 and 1985. The Minnesota Heart Survey

Abstract

Background and purpose: Age-adjusted stroke mortality rates declined approximately 50% between 1970 and 1990 in both the United States and Minnesota, but the reasons for this decline are not clear. This report examines possible improvements in short- and long-term survival of hospitalized definite stroke patients in the Minneapolis-St Paul (the Twin Cities) metropolitan area during this period.

Methods: Fifty percent random samples of patients discharged with an acute stroke diagnosis from area hospitals were selected in 1970 (n = 1200), 1980 (n = 1040), and 1985 (n = 896). Trained nurses abstracted pertinent clinical data from the hospital charts. By standardized clinical criteria similar to World Health Organization criteria (without computed tomography data), 376, 442, and 453 definite strokes were established for 1970, 1980, and 1985, respectively.

Results: Age- and sex-adjusted 28-day case fatality of definite stroke improved significantly from 1970 to 1985; the odds ratio (OR) of death within 28 days in 1985 (versus 1970) patients was 0.55 (95% confidence interval [CI], [0.39, 0.77]). Substantial improvements in 28-day mortality were observed both from 1970 to 1980 and from 1980 to 1985, although the latter change was not statistically significant. Further adjustment for predictors of early stroke mortality (such as level of consciousness) somewhat attenuated these results. Age- and sex-adjusted 5-year survival of definite stroke also improved significantly from 1970 to 1985 (OR, 0.72; 95% CI, [0.54, 0.96]), although the improvement was restricted to the 1970 to 1980 time period (OR, 0.76; 95% CI, [0.57, 1.01]). None of the survival trends differed significantly between men and women.

Conclusions: There were marked improvements in survival from 1970 to 1985 among hospitalized stroke patients in the Twin Cities. These improvements occurred almost exclusively in the acute hospitalization phase. Although the advent of computed tomography and improvements in hospital record-keeping during this period prevent an unequivocal conclusion, improved medical care and decreased severity of stroke probably contributed to gains in survival.