Association between tobacco smoking and the need for respiratory support and mortality in patients hospitalized with pneumonia

Objective To explore the impacts of smoking on the need for respiratory support and mortality in patients hospitalized with pneumonia. Methods A total of 24 367 patients hospitalized with pneumonia from 2009 to 2017 in the China Kadoorie Biobank, were included. Smoking status was self-reported, and data regarding respiratory support during hospitalization and mortality during follow-up were obtained from medical claims and death registries, respectively. OR, HR, and 95%CI were calculated and adjusted for potential confounders using logistic regression models and Cox proportional hazards regression models, respectively. Results Among males, current smokers or those who quit smoking due to illness had higher risks of requiring respiratory support (OR=1.15, 95%CI: 1.03-1.29), 1-year mortality (HR=1.66, 95%CI: 1.32-2.08), and 5-year mortality (HR=1.32, 95%CI: 1.13-1.54) following pneumonia hospitalization compared to nonsmokers. Male smokers who started smoking at a younger age or with longer smoking duration had the highest mortality risks (trend test both P<0.05). Female current smokers or those who quit smoking due to illness had higher risks of 1-year mortality (HR=1.62, 95%CI: 1.17-2.23) and 5-year mortality (HR=1.33, 95%CI: 1.06-1.67). We found no statistically significant difference in 90-day mortality between current smokers/those who quit smoking due to illness and nonsmokers. Conclusions Smoking was associated with higher risks of requiring respiratory support and mortality in patients hospitalized with pneumonia, especially among males and heavy smokers. These findings highlight the need for targeted strategies to promote smoking cessation in patients hospitalized with pneumonia.