Aspirin Use and Incident Stroke in the Cardiovascular Health Study

Abstract

Background and Purpose-Randomized clinical trials testing aspirin in relatively low-risk, middle-aged people have consistently shown small increases in stroke associated with aspirin use. We analyzed the relationship between the regular use of aspirin and incident ischemic and hemorrhagic stroke among people aged 65 years or older participating in the Cardiovascular Health Study. Methods-We conducted a multivariate analysis of incident stroke rates in a prospectively assessed, observational cohort of 5011 elderly people followed for a mean of 4.2 years. Results-Participants had a mean age of 72 years, and 58% were women. Twenty-three percent used aspirin frequently, and 17% used aspirin infrequently at study entry. Frequent aspirin use was associated with an increased rate of ischemic stroke compared with nonusers (relative riskϭ1.6; 95% confidence interval [CI], 1.2 to 2.2; Pϭ0.001). After adjustment for other stroke risk factors, women who used aspirin frequently or infrequently at study entry had a 1.8-fold (95% CI, 1.2 to 2.8) and 1.6-fold (95% CI, 0.9 to 3.0) increased risk of ischemic stroke, respectively (PϽ0.01, test for trend), compared with nonusers. In men, aspirin use was not statistically significantly associated with stroke risk. Findings were similar when aspirin use in the years before the incident stroke was used in the modeling. Aspirin use at entry was also associated with a 4-fold (95% CI, 1.6 to 10.0) increase in risk of hemorrhagic stroke for both infrequent and frequent users of aspirin (Pϭ0.003). Conclusions-Aspirin use was associated with increased risks of ischemic stroke in women and hemorrhagic stroke overall in this elderly cohort, after adjustment for other stroke predictors. The possibility exists of confounding by reasons for aspirin use rather than cause and effect. Whether regular aspirin use increases stroke risk for elderly people without cardiovascular disease can only be determined by randomized clinical trials. (Stroke. 1998;29:887-894.)

Antiplatelet Therapy in Acute Cerebral Ischemia

“…It is also of interest that several studies employing the prophylactic use of aspirin for stroke prevention in "low-risk" patients have reported either no benefit or an increase in stroke incidence. 27,28 These studies correlate well with earlier clinical observations that aspirin possesses antifibrinolytic 29 and/or thrombogenic 30 effect(s).…”

Aspirin in Alzheimer’s Disease

“…To rank the estimated risk of ICH in the AD population, we compared it with the results of a recent metaanalysis by the Antithrombotic Trialists' Collaboration (ATT) on aspirin in primary prevention (95 000 individuals; 660 000 person years; mean age, 56 years) and secondary prevention (17 000 individuals; 43 000 person years; mean age, 58 years) of vascular disease 7 and the Cardiovascular Health Study (CHS), an observational cohort study on aspirin therapy in a specifically elderly population (5011 individuals; mean age, 72 years). 8 The mean age in the EVA trial is 76 years; the median age in the AD2000 trial is 74 years. Both advanced age and AD seem to increase the risk of ICH in patients using aspirin (Figure).…”

“…Probability values of Ͻ0.05 indicate statistical significance. To compare the results with a recent metaanalysis on aspirin therapy 7 and an observational cohort study on aspirin therapy in a specifically elderly population, 8 we calculated the number of events per 1000 patient years.…”

Stroke and Its Prevention in Chronic Kidney Disease

“…Combined analysis of these two trials found a 32% (SD Ϯ8%) reduction in sustaining a nonfatal MI and a 13% (SD Ϯ 6%) reduction in combined vascular events but a statistically NS increase for nonfatal stroke of 18% (SD Ϯ13%) (69). One additional study (70) suggested that in low-risk patients, aspirin may actually be harmful. In that study, in which a cohort of 5011 elderly people from the Cardiovascular Health Study were followed for 4.2 yr, women had an increased risk for ischemic stroke and both men and women had an increased risk for hemorrhagic stroke.…”