Background & Purpose: Recent studies have suggested a “smoker’s paradox,” referring to higher recanalization rates and better outcomes after IV thrombolytic therapy for ischemic stroke in smokers compared to nonsmokers. Our goal was to evaluate whether this paradox exists for both IV and endovascular therapies (ET) in our population.
Methods: We retrospectively evaluated consecutive AIS patients (March 2014-April 2015) admitted to our comprehensive stroke center. Patients were stratified by treatment: IV tPA, ET, or neither. The primary endpoint was the modified Rankin scale (mRS) at discharge (“favorable outcome” score 0- 2) analyzed by logistic regression adjusted for demographic factors and admission NIHSS score. Successful reperfusion after ET was classified as Thrombolysis in Cerebral Infarction (TICI) scores of 2b or greater on immediate angiographic imaging.
Results: Of 765 patients, 29 % were smokers (n= 222) including 63 % white (Table). Among smokers, 15% received tPA and 3% of patients received ET. Among nonsmokers 14% received tPA and 6% received ET. There was no difference in favorable outcome between smokers and nonsmokers in patients treated with tPA (60.6% vs. 52.6%; P= 0.43) or ET (26% vs. 40.0%; P= 0.325). There was no difference between smokers and nonsmokers in re-canalization after ET (70.6 % vs. 70.0%; P= 0.62). In patients without tPA or ET treatment, favorable outcome was more frequent in smokers compared to nonsmokers (66.5% vs. 47.8 %; P< 0.001). In a regression model adjusted for admission NIHSS, age, gender, and race, the prevalence of good outcome in smokers was 18% more than nonsmokers. (PR 1.177; 95% CI: 1.021 - 1.409).
Conclusions: Our study did not support presence of the “Smoker’s Paradox” in AIS patients who receive IV or ET therapy. A rigorous adjustment for risk factors is likely to eliminate the paradoxical finding of more frequent favorable outcome in smokers who have not received tPA or ET.