Effect of Smoking on Mortality in Individuals With Chronic Obstructive Pulmonary Disease (COPD) in the United States

Background: Chronic Obstructive Pulmonary Disease (COPD) remains a significant public health challenge and a leading cause of mortality in the United States. Whereas the detrimental impact of smoking on COPD progression is well documented, the specific effects of smoking status on mortality risk among adults with COPD require further elucidation. Thus, this study investigates the relationship between smoking status (current smoker, former smoker, non-smoker) and mortality risk among patients diagnosed with COPD. Methods: We analyzed data from the National Health Interview Survey (NHIS), which was linked to mortality data from the National Death Index (NDI). Survival probabilities were estimated by using the Kaplan-Meier method, and the associations between smoking status and mortality risk were quantified by using hazard ratios (HR) and 95% CIs derived from univariate and multivariate Cox proportional hazards regression models. In the multivariate models, we adjusted for sex, age, marital status, heart condition, drinking status, body mass index, and health status. Results: The multivariate model revealed a significantly higher mortality risk for former smokers (HR 1.619, 95% CI 1.198-2.188) and current smokers (HR 1.894, 95% CI 1.386-2.590) compared with non-smokers. Marital status significantly modified the smoking status-mortality relationship in adults with COPD (P = .01), with single/never married former smokers exhibiting the highest mortality risk (HR 3.711, 95% CI 1.130-12.187). Conclusions: Both current and former smoking statuses are associated with an increased mortality risk in adults with COPD. These findings underscore the critical impact of smoking on mortality risk among adults with COPD and highlight the significant modifying effect of marital status.