Abstract
Background: Conflicting evidence has emerged regarding the relevance of smoking on risk of COVID-19 and its severity.
Methods: We undertook large-scale observational and Mendelian randomisation (MR) analyses using UK Biobank. Most recent smoking status was determined from primary care records (70.8%) and UK Biobank questionnaire data (29.2%). COVID-19 outcomes were derived from Public Health England SARS-CoV-2 testing data, hospital admissions data, and death certificates (until 18 August 2020). Logistic regression was used to estimate associations between smoking status and confirmed SARS-CoV-2 infection, COVID-19-related hospitalisation, and COVID-19-related death. Inverse variance-weighted MR analyses using established genetic instruments for smoking initiation and smoking heaviness were undertaken (reported per SD increase).
Results: There were 421 469 eligible participants, 1649 confirmed infections, 968 COVID-19-related hospitalisations and 444 COVID-19-related deaths. Compared with never-smokers, current smokers had higher risks of hospitalisation (OR 1.80, 95% CI 1.26 to 2.29) and mortality (smoking 1-9/day: OR 2.14, 95% CI 0.87 to 5.24; 10-19/day: OR 5.91, 95% CI 3.66 to 9.54; 20+/day: OR 6.11, 95% CI 3.59 to 10.42). In MR analyses of 281 105 White British participants, genetically predicted propensity to initiate smoking was associated with higher risks of infection (OR 1.45, 95% CI 1.10 to 1.91) and hospitalisation (OR 1.60, 95% CI 1.13 to 2.27). Genetically predicted higher number of cigarettes smoked per day was associated with higher risks of all outcomes (infection OR 2.51, 95% CI 1.20 to 5.24; hospitalisation OR 5.08, 95% CI 2.04 to 12.66; and death OR 10.02, 95% CI 2.53 to 39.72).
Interpretation: Congruent results from two analytical approaches support a causal effect of smoking on risk of severe COVID-19.
Keywords: COVID-19; clinical epidemiology; tobacco control.
【저자키워드】 COVID-19, clinical epidemiology, tobacco control., 【초록키워드】 primary care, Mortality, severe COVID-19, SARS-COV-2 infection, UK biobank, severity, Infection, risk, outcome, smoking, infections, death, Hospital admission, hospitalisation, smoking status, association, Evidence, Analysis, deaths, Support, smoker, Participants, higher risk, 95% CI, randomisation, white, Eligible participants, COVID-19-related death, questionnaire data, Public Health England, MOST, approach, risk of COVID-19, inverse, predicted, was used, reported, per day, was determined, 1.26, genetic instrument, MR analysis, SARS-CoV-2 testing data, 【제목키워드】 UK biobank, Cohort, randomisation,