Influence of differences in case mix on the better outcome of smokers after intravenous thrombolysis for acute cerebral ischemia.

BACKGROUND/AIMS: Thrombolysis for myocardial infarction is more effective in smokers. Our aim was to determine whether smokers treated by intravenous (i.v.) rt-PA for acute cerebral ischemia have better outcomes.

METHOD

Comparison of smokers and non-smokers for baseline characteristics and month-3 outcome in patients treated by i.v. rt-PA for cerebral ischemia in Lille, France, and Belgrade, Serbia. The primary outcome was a modified Rankin scale (mRS) 0-1 or similar to the pre-stroke mRS. Secondary outcomes were an mRS 0-2 and death.

RESULTS

We included 459 patients (255 men; median age 65 years, interquartile range 52-76; 135 smokers). Smokers were younger (median 53 vs. 70 years, p < 0.0001) and had less severe strokes (median NIHSS 10 vs. 14, p < 0.0001). At month 3, they were more likely to have an mRS 0-1 [odds ratio (OR) 1.75; 95% confidence interval (CI) 1.17-2.62], or an mRS 0-2 (OR 2.90; 95% CI 1.86-4.52) and less likely to be dead (OR 0.28; 95% CI 0.13-0.61). Smoking was not independently associated with outcome after adjustment for case mix [adjusted OR ((adj)OR) 0.86; 95% CI 0.52-1.43].

CONCLUSION

Smoking does not independently influence the outcome in patients treated by rt-PA for cerebral ischemia. The better outcome in smokers is the consequence of differences in case mix.