The impact of smoking on COVID-19-related mortality: a Brazilian national cohort study

•This study revealed a substantial impact of smoking on COVID-19 outcomes.•Smokers have higher mortality and intensive care unit admission rates than never-smokers.•Smoking was a significant independent risk factor for severe COVID-19 outcomes. Current evidence suggests the potential heightened vulnerability of smokers to severe coronavirus disease (COVID-19) outcomes. This study aimed to analyze the clinical outcomes and mortality related to tobacco use in a cohort of hospitalized Brazilian COVID-19 patients. This retrospective cohort study analyzed adults hospitalized for COVID-19 in Brazil using the SIVEP-Gripe database (official data reported by public and private healthcare facilities for monitoring severe acute respiratory syndrome cases in Brazil). The inclusion criteria were patients over 18 years of age with a positive RT-qPCR test for SARS-CoV-2. The analysis focused on in-hospital mortality, considering smoking as an exposure variable, and included covariates such as age, gender, and comorbidities. Smoking history was collected from the self-reported field in the database. Statistical analyses included descriptive statistics, crude Odds Ratios, and multivariable binary logistic regression. This study included 2,124,285 COVID-19 patients, among whom 44,774 (2.1 %) were smokers. The average age of the smokers was higher than that of the never-smokers (65.3 years vs. 59.7 years). The clinical outcomes revealed that smokers had higher rates of intensive care unit admission (51.6 % vs. 37.2 % for never-smokers), invasive ventilatory support (31.5 % vs. 20.2 % for never-smokers), and higher mortality (42.7 % vs. 31.8 % for never smokers). In the multivariable analysis, smokers demonstrated a heightened risk of death (aOR 1.23; 95 % CI 1.19–1.25). This large populational-based cohort study confirms the current evidence and underscore the critical importance of recognizing smoking as a substantial risk factor for adverse outcomes in COVID-19 patients.