The Ticlopidine Aspirin Stroke Study (TASS) suggested that, compared with whites, blacks might benefit preferentially from ticlopidine therapy. Given this suggestive data and the high stroke burden in blacks, Gorelick and colleagues designed the African American Anti-platelet Stroke Prevention Study (AAASPS) to determine the role of aspirin compared with ticlopidine in preventing recurrent stroke and cardiovascular events.
Patients were randomized in a 1:1 ratio to aspirin or ticlopidine with the hypothesis that, in a black population, 500 mg per day of ticlopidine would be more effective in preventing recurrent stroke, myocardial infarction (MI), or vascular death than 650 mg per day of aspirin. Study participants with a recent history of ischemic stroke were followed for up to two years after randomization.
Of the 1,809 participants, 902 patients were in the ticlopidine group, and 907 were in the aspirin group. Because of futility analyses suggesting a less than 1 percent chance that patients taking ticlopidine would have better outcomes than patients taking aspirin, the study continued to completion in unblended fashion, with patients opting to continue or return to care in their community.
Of the 245 primary outcomes (the composite of recurrent stroke, MI, or vascular death), 133 occurred in the ticlopidine group and 112 in the aspirin group, with no statistically significant difference between the two. Although a slight excess of strokes in the ticlopidine group was not statistically significant, Kaplan-Meier curves indicated a trend toward a statistically significant difference in time to fatal or nonfatal stroke favoring the aspirin group. Overall, the two-year primary event rate was 19.7 percent among the patients taking ticlopidine compared with 16.3 percent in the patients taking aspirin.
Ticlopidine has been shown to be effective in preventing stroke, with a marginally significant difference in the prevention of recurrent stroke or death from any cause compared with aspirin. In this trial, ticlopidine did not reduce the composite outcome of recurrent stroke, MI, or vascular death. A trend toward statistically significant fatal or nonfatal stroke reduction favored the aspirin group, and analyses suggested a 40 to 50 percent likelihood that aspirin would be significantly better in preventing this outcome if the trial continued to completion. Slightly more adverse effects occurred in the ticlopidine group.
The authors conclude that aspirin is a reasonable first choice in preventing noncardioembolic stroke in black patients.