Smoking status related to Covid-19 mortality and disease severity in a veteran population

Introduction: Cigarette smoking is associated with development of significant comorbidities. Patients with underlying comorbidities have been found to have worse outcomes associated with Coronavirus Disease 2019 (Covid-19). This study evaluated 30-day mortality in Covid-19 positive patients based on smoking status. Methods: This retrospective study of veterans nationwide examined Covid-19 positive inpatients between March 2020 and January 2021. Bivariate analysis compared patients based on smoking history. Propensity score matching adjusted for age, gender, race, ethnicity, Charlson comorbidity index (0-5 and 6-19) and dexamethasone use was performed. A multivariable logistic regression with backwards elimination and Cox Proportional Hazards Ratio was utilized to determine odds of 30-day mortality. Results: The study cohort consisted of 25,958 unique Covid-19 positive inpatients. There was a total of 2,995 current smokers, 12,169 former smokers, and 8,392 non-smokers. Death was experienced by 13.5% (n = 3503) of the cohort within 30 days. Former smokers (OR 1.15; 95% CI, 1.05-1.27) (HR 1.13; 95% CI, 1.03-1.23) had higher risk of 30-day mortality compared with non-smokers. Former smokers had a higher risk of death compared to current smokers (HR 1.16 95% CI 1.02-1.33). The odds of death for current vs. non-smokers did not significantly differ. Conclusion: Compared to veteran non-smokers with Covid-19, former, but not current smokers with Covid-19 had a significantly higher risk of 30-day mortality.