Impact of Smoking on the Mortality of Hospitalized Patients With COVID-19, Iran: A Cross-sectional Study

Background: There are inconsistent data about the association of smoking with the prognosis of hospitalized patients with COVID-19. This inconsistency is so huge that some investigators have suggested some protective roles for smoking against COVID-19 disease.  Objective: This study was designed to investigate the association of smoking with mortality in hospitalized patients with COVID-19. Methods: This cross-sectional study was conducted on 493 adult patients with COVID-19 disease. Other underlying diseases, clinical and laboratory findings, and mortality rates were compared between smoking and non-smoking patients using univariate and multivariate analyses. Results:  The prevalence of current smoking among hospitalized patients was 6.1%. Clinical complaints and disease severity at admission were similar between smokers and non-smokers. Leukocyte count and blood sugar were higher in smokers compared to non-smokers (P=0.003, P=0.018, respectively). The rate of ICU admission and days of hospitalization were comparable between smokers and non-smokers. However, smokers had a significantly higher mortality rate than non-smokers (36.7% vs 13.8%, respectively, P=0.001). After adjusting for significantly different variables in univariate analysis, smoking was associated with a 3.78 times higher mortality rate (OR=3.78, 95% CI: 1.48-9.67, P=0.005). Conclusion: Smoking is an independent predictor of mortality in hospitalized patients with COVID-19.