Journal article
Smoking and COVID-19 outcomes: an observational and Mendelian randomisation study using the UK Biobank cohort
- Abstract:
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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.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, 677.1KB, Terms of use)
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- Publisher copy:
- 10.1136/thoraxjnl-2021-217080
Authors
- Publisher:
- BMJ
- Journal:
- Thorax More from this journal
- Volume:
- 77
- Issue:
- 1
- Pages:
- 65-73
- Publication date:
- 2021-09-27
- Acceptance date:
- 2021-06-14
- DOI:
- EISSN:
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1468-3296
- ISSN:
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0040-6376
- Language:
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English
- Keywords:
- Pubs id:
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1196112
- Local pid:
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pubs:1196112
- Deposit date:
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2021-09-28
Terms of use
- Copyright holder:
- Clift et al.
- Copyright date:
- 2021
- Rights statement:
- © Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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