Systematic review and meta-analysis of the impact of depression on subsequent smoking cessation in patients with coronary heart disease: 1990-2013

Objective: Smoking cessation is crucial for patients with coronary heart disease (CHD), yet depression may impede cessation success. We systematically reviewed the longitudinal association between depression and subsequent smoking cessation in individuals with CHD in order to quantify this effect. Methods: Electronic databases (PsychInfo, PubMed, CINAHL) were searched for prospective studies of CHD patients which measured depression at baseline (scales, diagnostic interview or antidepressant prescription) and reported smoking continuation/cessation at follow-up. Inclusive dates were 1st January 1990 to 22nd May 2013. Standardized mean differences (SMD) and associated 95% confidence interval (CI) were estimated using random effects meta-analysis. Sensitivity analysis explored the impact of limiting meta-analysis to studies using different depression measures (validated scales, diagnostic interviews, antidepressant prescription), different durations of follow-up, or higher quality studies. Results: From 1451 citations retrieved, 28 relevant articles were identified. Meta-analysis of all available data from 20 unique datasets found that depressed CHD patients were significantly less likely to quit smoking at follow-up (SMD=-.39, 95% CI -.50 to -.29; I2=51.2%, p=.005). Estimates remained largely unchanged for each sensitivity analysis, except for two studies that used antidepressants, which showed a much larger effect (SMD=-.94, -1.38 to -.51; I2=57.7%, p=.124). Conclusions: CHD patients with depressive symptoms are significantly less likely to quit smoking than their non-depressed counterparts. This may have implications for cardiovascular prognosis, and CHD smokers may require aggressive depression treatment to enhance their chances of quitting.