Smoking is not associated with recurrence and retreatment of intracranial aneurysms after endovascular coiling
Authors: Brinjikji Waleed , Lingineni Ravi K. , Gu Chris N. , Lanzino Giuseppe , Cloft Harry J. , Ulsh Lauren , Koeller Kristen , Kallmes David F. 
Published: November 2014

OBJECT
Tobacco smoking is one of the most important risk factors for the formation of intracranial aneurysms and for aneurysmal subarachnoid hemorrhages. Smoking has also been suggested to contribute to the recurrence of aneurysms after endovascular coiling. To improve the understanding of the impact of smoking on long-term outcomes after coil embolization of intracranial aneurysms, the authors studied a consecutive contemporary series of patients treated at their institution. The aims of this study were to determine whether smoking is an independent risk factor for aneurysm recurrence and retreatment after endovascular coiling.

METHODS
All patients who had received an intrasaccular coil embolization of an intracranial aneurysm, who had undergone a follow-up imaging exam at least 6 months later, and whose smoking history had been recorded from January 2005 through December 2012 were included in this study. Patients were stratified according to smoking status into 3 groups: 1) never a smoker, 2) current smoker (smoked at the time of treatment), and 3) former smoker (quit smoking before treatment). The 2 primary outcomes studied were aneurysm recurrence and aneurysm retreatment after treatment for endovascular aneurysms. Kruskal-Wallis and chi-square tests were used to test statistical significance of differences in the rates of aneurysm recurrence, retreatment, or of both among the 3 groups. A multivariate logistic regression analysis controlling for smoking status and for several characteristics of the aneurysm was also performed.

RESULTS
In total, 384 patients with a combined total of 411 aneurysms were included in this study. The aneurysm recurrence rate was not significantly associated with smoking: both former smokers (OR 1.00, 95% CI 0.61–1.65; p = 0.99) and current smokers (OR 0.58, 95% CI 0.31–1.09; p = 0.09) had odds of recurrence that were similar to those who were never smokers. Former smokers (OR 0.78, 95% CI 0.46–1.35; p = 0.38) had odds of retreatment similar to those of never smokers, and current smokers had a lower odds of undergoing retreatment (OR 0.44, 95% CI 0.21–0.91; p = 0.03) than never smokers. Moreover, an analysis adjusting for aneurysm rupture, diameter, and initial occlusion showed that former smokers (OR 0.65, 95% CI 0.33–1.28; p = 0.21) and current smokers (OR 1.04, 95% CI 0.60–1.81; p = 0.88) had odds of aneurysm recurrence similar to those who were never smokers. Adjusting the analysis for aneurysm rupture, diameter, and occlusion showed that both former smokers (OR 0.49, 95% CI 0.23–1.05; p = 0.07) and current smokers (OR 0.82, 95% CI 0.46–1.46; p = 0.50) had odds of retreatment similar to those of patients who were never smokers.

CONCLUSIONS
The results show that smoking was not an independent risk factor for aneurysm recurrence and aneurysm retreatment among patients receiving endovascular treatment for intracranial aneurysms at the authors' institution. Nonetheless, patients with intracranial aneurysms should continue to be counseled about the risks of tobacco smoking.