Impact of Smoking on mortality of hospitalized patients with COVID-19: a cross sectional study in Iran

Objectives: There are inconsistent data about the association of smoking with prognosis in hospitalized patients with COVID-19. This inconsistency is so huge that some investigators hypothesized some protective roles of smoking against COVID-19 disease. This study has been 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: Prevalence of current smoking among hospitalized patients was 6.1%. Clinical complaints and disease severity at admission were similar between smokers and non-smokers. Leukocytes count and blood sugar were higher in smokers compared to non-smokers (p=0.003, p=0.018, respectively). Rate of ICU admission and days of hospitalization were not different between smokers and non-smokers. However, smokers had a significantly higher mortality rate compared to non-smokers (36.7% vs 13.8%, respectively, p=0.001). After adjusting for significantly different variables in univariate analysis, smoking was associated with 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.