VANCOUVER, BC—Clopidogrel was more effective at decreasing further strokes in non-cardioembolic ischemic stroke patients if they were active smokers. The finding comes from a new study presented at the 68th AAN Annual Meeting.

Previous data have suggested that smoking is associated with an enhanced clopidogrel effect vs. aspirin in patients after a myocardial infarction, though this study is the first to test whether the paradoxical benefit exists in patients with non-cardioembolic ischemic stroke. 

Study authors from the Xuanwu Hospital Capital Medical University evaluated a total of 1,910 non-cardioembolic ischemic stroke patients in a single-center retrospective study that compared treatment with clopidogrel vs. aspirin. The study patients were discharged from the hospital between 2013 and 2014 and were followed for 12 months. The primary outcome was a composite of ischemic stroke, myocardial infarction and all-cause-death; the secondary outcome was ischemic strokes alone.

Of the study cohort, 844 were categorized as non-smokers and 1,066 were active smokers—defined as smoking at least half a pack of cigarettes per day.

Rates of the primary outcome (ischemic stroke, myocardial infarction, all-cause-death) were lower in the clopidogrel group compared to the aspirin group (12 [3.7%] vs. 50 [7.3%], adjusted odds ratio [OR] 0.58, 95% CI: 0.31–1.07; P=0.28). The enhanced effect of clopidogrel in smokers compared to aspirin was further demonstrated among non-smokers in regards to the primary outcome (7 [2.6%] vs. 14 [2.4%], adjusted OR 0.100, 95% CI: 0.39–2.53; P=1.00).

The difference between the study groups was also similar when analyzed for ischemic stroke alone, with lower rates observed among smokers in the clopidogrel vs. aspirin group (12 [3.1%] vs. 34 [5.0%], adjusted OR 0.60, 95% CI: 0.31–1.18; P=0.14). Among non-smokers, however, the difference was less apparent between the clopidogrel vs. aspirin groups (P=0.77).

Ischemic stroke patients who were active smokers “derived a slight yet non-statistically significant benefit from clopidogrel compared to aspirin for vascular risk reduction,” concluded lead author of the study, Dr. Qian Zhang. The authors added that more studies of larger cohorts are needed to further investigate the association between smoking and the effects of clopidogrel.