Association of depression and smoking cessation: outcomes of an 18-year retrospective cohort study.

Background: Depression is frequently associated with unsuccessful smoking cessation.

Objective: In this study, we investigated the impact of depression history on smoking cessation success in a clinical setting.

Methods: This retrospective study included 726 patients who visited our smoking cessation clinic between January 1, 2001, and December 31, 2018. Kaplan-Meier analyses and Cox proportional hazards regression models were used to perform univariate and multivariate analyses of smoking cessation success factors.

Results: Among the 726 patients, 76 had a history of depression and demonstrated significantly lower 12-week quit rate compared to those without (33.6% vs. 69.6%, p < .001). Multivariate Cox analysis revealed a significant association between abstinence rate and history of depression (hazard ratio 2.251, 95% CI 1.505-3.315, p < .001), history of schizophrenia (hazard ratio 2.716, 95% CI 1.427-4.840, p = .003), and Fagerström Nicotine Dependence Test scores (hazard ratio 1.519, 95% CI 1.053-2.197, p = .025).

Conclusions: Our findings suggested that a history of depression is a significant prognostic factor for smoking cessation, underscoring the need for targeted interventions for patients with a history of depression. The findings of this study are subject to potential selection bias due to recruitment from a single hospital, which may limit the generalizability of our results. This study highlights the necessity for novel, specialized smoking cessation therapies to support patients with a history of depression in their cessation journey.