Impact of Stroke Severity on the Smoking Paradox in Patients Treated with Intravenous Thrombolysis.

Objective: To our knowledge, no previous studies have investigated the impact of stroke severity on the smoking paradox after intravenous thrombolysis (IVT). We aimed to explore the contribution of stroke severity to the association between smoking and stroke prognosis after IVT.

Methods: We enrolled consecutive patients who received IVT within 4.5 hours from stroke onset. A logistic regression model was used to estimate the unadjusted and adjusted odds ratios (ORs) with their 95% confidence intervals (CIs) for poor functional outcome and mortality at 3 months.

Results: Among patients with moderate stroke, smokers experienced a lower risk of 3-month poor outcomes than non-smokers (33.0% vs. 44.4%, unadjusted OR: 0.616; 95% CI: 0.402-0.945). However, among those with severe stroke, smokers had a higher risk of 3-month poor outcomes than non-smokers (81.6% vs. 55.9%, unadjusted OR: 3.496; 95% CI: 1.207-10.127). After adjustment, the negative correlation between smoking and 3-month poor outcome following IVT lost statistical significance in patients with moderate stroke (OR: 0.677 [95% CI: 0.418-1.097]). However, smoking remained a risk factor for 3-month poor outcomes in patients with severe stroke (OR: 4.216 [95% CI: 1.236-14.385]). We also observed a significant interaction between smoking and stroke severity with regard to the risk of poor functional outcomes (p=0.023). However, no such interaction influenced mortality (p=0.901).

Conclusion: Stroke severity affects the association between smoking and 3-month clinical functional outcomes following IVT.