Tobacco Smoking And Severity Of Covid-19: Experience From A Hospital-Based Prospective Cohort Study In Lyon, France

Information gathered so far from published studies attest the existence of a complex relationship between tobacco smoking and the severity of COVID-19. We investigated the association between smoking habits and the severity of COVID-19 in patients hospitalized in university-affiliated hospitals in Lyon, France. Baseline sociodemographic, clinical and biological characteristics of adult COVID-19 hospitalized patients presenting from the community were prospectively collected and analyzed. Tobacco exposure was documented at admission. Characteristics of patients hospitalized in medical wards to those admitted or transferred to intensive care units (ICUs) were compared using Mann-Whitney and X-2 or Fisher's exact test. A composite endpoint including admission or transfer to ICU or death was created as a proxy for severe outcome. Adjusted odds ratio (aOR) and 95% confidence interval (95% CI) were calculated to identify variables independently associated with a severe outcome. Of the 645 patients with documented information on smoking habits, 62.6% were never-smokers, 32.1% ex-smokers, and 5.3% active smokers. Past tobacco use was independently associated with an increased risk of severe outcome (aOR: 1.71; 95% CI: 1.12-2.63), whereas a nonsignificant protective trend was found for active smoking. The results suggest that past smoking is associated with enhanced risk of progressing toward severe COVID-19 disease in hospitalized patients.