Time trends in long-term survival after stroke: the Northern Sweden Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) study, 1985-1994.

Abstract

Stroke mortality rates and case fatality of stroke have declined since the beginning of the 1970s in Sweden, but the incidence of stroke has been stable. The aim of this study was to analyze trends in long-term survival after stroke. Within the framework of the population-based WHO Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) Project, all acute stroke events were recorded in the age group 25 to 74 years in northern Sweden during the period 1985 to 1994. All first-ever stroke patients were followed for information on vital status (minimum follow-up time was 1 year). Survival time was related to time period of stroke onset, stroke diagnosis, and concomitant diseases. Survival times for a total of 6819 first-ever stroke patients (4057 men and 2762 women) were analyzed. Age-adjusted odds ratio for death within 1 year after stroke was 0.70 (95% confidence interval [CI], 0.55 to 0.88) in the period 1993 to 1994 as compared with the period 1985 to 1986 in men and 0.69 (95% CI, 0.53 to 0.90) in women. Corresponding odds ratios were 0.73 in men and 0.70 in women among those who survived the first 28 days. Similar improvements were seen for 3- and 5-year survival. Improvements in survival over time were most marked among patients with ischemic stroke. There was no improvement in survival over time among patients with the most severe deficits at onset. Gradually improved survival, both short and long term, was observed during the 10-year study period. The improvements are not explained by changes in known confounding prognostic factors.