Association between smoking status and death from COVID-19 in South Korea: A nationwide cohort study

INTRODUCTION: This study examined the association between smoking status and death from COVID-19. METHODS: This study used nationwide cohort data collected from the Korean National Health Insurance Service, linking to information on all individuals who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The smoking status of subjects who participated twice in national health screenings between 2015 and 2018 was measured. This study investigated death from COVID-19 among those who tested positive from 1 January to 30 May 2020. RESULTS: This study included 4259 patients who tested positive for SARS-CoV-2 in Korea. After adjusting for all potential confounding factors, current smokers (adjusted odds ratio, AOR=3.75; 95% CI: 1.23–11.36) and recent quitters (AOR=3.74; 95% CI: 1.12–12.53) were associated with an increased risk of death from COVID-19 compared to never smokers. Compared with current smokers, long-term quitters (AOR=0.33; 95% CI: 0.11–0.95) and never smokers (AOR=0.27; 95% CI: 0.09–0.81) were associated with a reduced risk of death from COVID-19. CONCLUSIONS: Smoking was associated with an increased risk of death among patients with COVID-19. Given the lower possibility of death in long-term quitters with COVID-19, continuous smoking cessation among smokers or recent quitters is needed.