Illicit drug use as a predictor of smoking cessation treatment outcome

Evidence from cross-sectional survey data suggests a negative association between illicit drug use and smoking cessation. In a prospective clinical cohort, we examined whether illicit drug users were less successful than other smokers when making an attempt to stop smoking.

A total of 100 smokers attending a tobacco dependence clinic were studied. Pretreatment questionnaire measures of illicit drug use, demographics, health history, and tobacco smoking were taken. Treatment consisted of seven weekly behavioral support sessions plus nicotine replacement therapy or bupropion. Short-term outcome was assessed at the end of the treatment by self-report and carbon monoxide (CO) verification.

A total of 24 smokers (24%) had used illicit drugs during the previous 30 days. Drug users were less likely to stop smoking than were nonusers. The difference in CO-verified success rates was 26.1% (29.2% vs. 55.3%, 95% CI = 4.8%-47.4%), and the odds ratio was 0.33 (95% CI = 0.12-0.89). Adjustment for group differences on all the measured background and treatment characteristics affected this result only marginally.

Illicit drug use appears to have a significant detrimental effect on the success of an attempt to stop smoking. This effect is not explained by differences between drug users and nonusers on established prognostic factors. These first results in a prospective sample support findings from a large U.S. population survey of smoking cessation rates in drug users and nonusers. If these results are corroborated, clinicians treating smokers should consider developing new protocols to improve outcomes in smokers using illicit drugs.