Past major depression and smoking cessation outcome: A systematic review and meta-analysis update

Aims: To update our prior meta-analysis that showed past major depression (MD+) to be unrelated to smoking cessation outcome. Methods: Eligible trials included 14 from our original review and 28 identified through an updated systematic review (2000-2009). We coded for assessment of past MD, exclusion for recent MD episode (MDE; ≤6 months versus no exclusion), duration/modality of cognitive behavioral treatment (CBT; face-to-face versus self-help) and other factors. To minimize influence of experimental treatments that may selectively benefit MD+ smokers we analyzed placebo/lowest intensity control arms only. Study-specific ORs for the effect of past MD on short-term (≤3 months) and long-term (≥6 months) abstinence were estimated and combined using random effects. Two-way interaction models of past MD with study methodology and treatment factors were used to evaluate hypothesized moderators of the past MD-abstinence association. Results: MD+ smokers had 17% lower odds of short-term abstinence (n=35, OR=0.83, 95% CI=0.72-0.95, P=0.009) and 19% lower odds of long-term abstinence (n=38, OR=0.81, 95% CI=0.67-0.97, P=0.023) than MD- smokers after excluding the sole study of varenicline because of its antidepressant properties. The association between past MD and abstinence was affected by methodological (recent MDE exclusion, type of MD assessment) and treatment (CBT modality) factors. Conclusions: Past major depression has a modest adverse effect on abstinence during and after smoking cessation treatment. An increased focus on the identification of effective treatments or treatment adaptations that eliminate this disparity in smoking cessation for MD+ smokers is needed.