Daily aspirin does not significantly reduce the risk of a first fatal or nonfatal stroke in older patients with vascular risk factors. Shinichiro Uchiyama, MD, PhD, International University of Health and Welfare, Sanno Hospital and Sanno Medical Center, Tokyo, Japan, presented an analysis of the effect of aspirin for primary prevention of stroke in the Japanese Primary Prevention Project (JPPP) [Ikeda Y et al. JAMA. 2014].

The effect of aspirin on the primary prevention of stroke varies among clinical trials conducted in Western countries, and no data have been available on the effect of aspirin in an Asian population, which is at higher risk of intracranial hemorrhage than a white population.

JPPP included 14 464 Japanese patients aged 60 to 85 years (mean age, 70 years) who presented with hypertension, dyslipidemia, or diabetes [Ikeda Y et al. JAMA. 2014]. Patients were randomized 1to 1 to receive aspirin 100 mg once daily or no aspirin, in addition to ongoing medications. Follow-up was a median of 5.02 years, with a maximum follow-up of 6.5 years.

The primary end point was a composite of death from cardiovascular causes (myocardial infarction, stroke, and other cardiovascular causes), nonfatal stroke (ischemic or hemorrhagic, including undefined cerebrovascular events), and nonfatal myocardial infarction.

The main results of JPPP showed no significant effect of aspirin on the primary composite end point (HR, 0.94; 95% CI, 0.77 to 1.15; P = .54). The prevalence of risk factors in the aspirin and no aspirin groups at baseline are shown in Table 1.

In the analysis, the number of fatal and nonfatal strokes was 128 in each group. In analyzing the data further however, the type of stroke that occurred did vary, depending on the use or non-use of aspirin. Ischemic stroke was less frequent in the aspirin vs no aspirin group (85 vs 102), but hemorrhagic stroke was more common in the aspirin group (38 vs 23). Additionally, the number of transient ischemic attacks (TIAs) was nearly half that in the aspirin vs no aspirin group (19 vs 34).

The cumulative rate of any stroke or TIA at 5 years was not different between the groups (adjusted HR, 0.927; 95% CI, 0.741 to 1.60; P = .509). The cumulative rate of any stroke at 5 years was also not significantly different (adjusted HR, 1.011:95% CI, 0.791 to 1.291; P = .932).

The rate of ischemic stroke was lower in the aspirin vs no aspirin group, although this difference failed to achieve significance (adjusted HR, 0.842; 95% CI, 0.631 to 1.123; P = .240).

Cerebral hemorrhage was almost twice as common in the aspirin vs no aspirin group (28 vs 15, respectively), while the rates of subarachnoid hemorrhage, subdural hematoma, and other hemorrhage were comparable. The cumulative rate of intracranial hemorrhage was not significantly different between the groups (adjusted HR, 1.463; 95% CI, 0.956 to 2.237; P = .078). Significant risk factors for cerebrovascular events are listed in Table 2.

The rate of any stroke or TIA was not significantly different between patients randomized to aspirin or no aspirin in the low-risk or the high-risk groups based on a stroke risk score.