Abstract: Forty-nine RCTs were included of which 33 trials investigated smoking cessation interventions with specific mood management components for depression. In smokers with current depression, meta-analysis showed a significant positive effect for adding psychosocial mood management to a standard smoking cessation intervention when compared with standard smoking cessation intervention alone (11 trials, N = 1844, RR 1.47, 95% CI 1.13 to 1.92). In smokers with past depression we found a similar effect (13 trials, N = 1496, RR 1.41, 95% CI 1.13 to 1.77). Meta-analysis resulted in a positive effect, although not significant, for adding bupropion compared with placebo in smokers with current depression (5 trials, N = 410, RR 1.37, 95% CI 0.83 to 2.27). There were not enough trial data to evaluate the effectiveness of fluoxetine and paroxetine for smokers with current depression. Bupropion (4 trials, N = 404, RR 2.04, 95% CI 1.31 to 3.18) might significantly increase long-term cessation among smokers with past depression when compared with placebo, but the evidence for bupropion is relatively weak due to the small number of studies and the post hoc subgroups for all the studies. There were not enough trial data to evaluate the effectiveness of fluoxetine, nortriptyline, paroxetine, selegiline, and sertraline in smokers with past depression. Twenty-three of the 49 trials investigated smoking cessation interventions without specific components for depression. There was heterogeneity between the trials which compared psychosocial interventions with standard smoking cessation counselling for both smokers with current and past depression. Therefore, we did not estimate a pooled effect. One trial compared nicotine replacement therapy (NRT) versus placebo in smokers with current depression and found a positive, although not significant, effect (N = 196, RR 2.64, 95% CI 0.93 to 7.45). Meta-analysis also found a positive, although not significant, effect for NRT versus placebo in smokers with past depression (3 trials, N = 432, RR 1.17, 95% CI 0.85 to 1.60). Three trials compared other pharmacotherapy versus placebo and six trials compared other interventions in smokers with current or past depression. Due to heterogeneity between the interventions of the included trials we did not estimate pooled effects. Evidence suggests that adding a psychosocial mood management component to a standard smoking cessation intervention increases long-term cessation rates in smokers with both current and past depression when compared with the standard intervention alone. Pooled results from four trials suggest that use of bupropion may increase long-term cessation in smokers with past depression. There was no evidence found for the use of bupropion in smokers with current depression. There was not enough evidence to evaluate the effectiveness of the other antidepressants in smokers with current or past depression. There was also not enough evidence to evaluate the group of trials that investigated interventions without specific mood management components for depression, including NRT and psychosocial interventions.

Plain-language summary: In this review, treatments were divided into those with or without specific attention to handling depression. We found that smoking cessation treatments with specific attention to handling depression helped smokers who suffered from depression to quit. Psychosocial 'mood management' interventions, where participants learn how to handle depressive symptoms with psychological techniques, were effective in those with current depression and with a history of it. Bupropion, an antidepressant medication to help quit smoking, has been shown to be effective for smoking cessation in healthy smokers. Our findings show that bupropion may benefit smokers with a history of depression as well. However, this was not found for those with current depression. There was a lack of evidence for the effectiveness of other antidepressants to help smokers with a history of depression to quit. There was also not enough evidence for the use of antidepressants in smokers with current depression. Although treatments without specific attention to handling depression, such as nicotine replacement therapy and standard psychosocial smoking cessation interventions, have been shown to help other groups of people to quit smoking, there was not enough evidence to show that they were helpful in people with a history of or with current depression.