Stroke is the fourth leading cause of death in the United States and a major contributor to disability. In the last few decades, efforts have been focused on modifying vascular risk factors in order to prevent stroke as well as on the development of acute stroke therapies that aim to decrease morbidity and mortality. In a large, population-based study, Koton and colleagues (2014) endeavored to determine whether these efforts have led to changes in stroke incidence and mortality over time.
The authors examined trends from the Atherosclerosis Risk in Communities (ARIC) cohort between 1987 and 2011. This prospective cohort study of >15,000 people (>282,000 person-years) took place in four different communities in the United States. Participants underwent a baseline interview and physical examination followed by periodic exams, phone interviews, and active surveillance of discharge data from local hospitals.
A total of 14,357 patients were included in this study after exclusion of those with a history of stroke (n = 779) at the beginning of the study and others with missing data points regarding vascular risk factors. The mean age at baseline was 54.1 years, and 55% of the participants were women. Over the time course of the study, which had a median length of follow-up of 22.5 years, the use of cholesterol-lowering medications increased and smoking rates decreased, but there was an increase in the proportion of patients with diabetes and hypertension.
A total of 929 patients had an incidence of ischemic stroke, and 140 had an incident hemorrhagic stroke during the study period. Incidence rates were 3.73 [95% confidence interval (CI), 3.51–3.96] per 1000 person-years for total stroke, 3.29 (95% CI, 3.08–3.50) per 1000 person-years for ischemic stroke, and 0.49 (95% CI, 0.41–0.57) per 1000 person-years for hemorrhagic stroke. Stroke incidence was found to decrease over time in both white and black participants (incidence rate ratio for both groups, 0.76; 95% CI, 0.66–0.87; absolute decrease of 0.93 per 1000 person-years), although this decrease was found only in those older than 65 years. This decreased incidence was similar across sexes as well.
Mortality after hemorrhagic stroke was higher than that following ischemic stroke. Like incidence, mortality after stroke was found to significantly decrease over time (hazard ratio, 0.80; 95% CI, 0.66–0.98; absolute decrease of 8.09 per 100 strokes per 10-year period). This mortality decrease was similar across race and sex but was mainly driven by a decrease in those younger than 65 years. Use of cholesterol-lowering medications was associated with a decreased mortality, and diabetes and current smoking were associated with an increased mortality.
This important population-based study suggests that we are making some strides in the quest to decrease stroke incidence and mortality, a major public health concern. Rates of stroke remain higher in blacks and men, but this study demonstrates progress across all patient populations. Decreases in incidence and mortality likely reflect, respectively, better risk factor modification and improved stroke treatment. While there remains a long way to go in stroke prevention and therapy, these encouraging results suggest we are on the right track, and clinicians should be urged to discuss stroke risk and recognition with all of their patients.
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