Systematic review and meta-analysis of the impact of depression on subsequent smoking cessation in patients with chronic respiratory conditions.

OBJECTIVE To systematically review the impact of depression on subsequent smoking cessation in prospective studies of chronic respiratory patients. METHOD A systematic search of electronic databases (MEDLINE, PsycINFO, CINAHL) was conducted to identify prospective studies of chronic respiratory patients that measured depression at baseline and smoking status at follow-up, dating from 1st January 1990 to 21st February 2014. The standardized mean difference (SMD) and 95% confidence interval (CI) for the association between baseline depressive symptoms and subsequent smoking cessation was estimated from available data using random effects meta-analysis. RESULTS A total of 1314 citations were retrieved and 197 articles were further evaluated by two reviewers. Seven articles provided sufficient data to estimate the association between depressive symptoms and subsequent smoking cessation. Those with elevated depressive symptoms were significantly less likely to quit smoking at follow-up than those not reporting elevated depressive symptoms (SMD=-.31, 95% CI -.43 to -.19; I(2)=0%, P=.506). CONCLUSIONS The association between depression and subsequent smoking was poorly reported or omitted in most studies. However, the available evidence suggests that depression decreases the likelihood that patients with chronic respiratory conditions will quit smoking. Future research is needed to determine how best to manage depression and smoking cessation in this population.