Smoking and COVID-19 outcomes: an observational and Mendelian randomized study using the UK Biobank cohort 

Clift AK, von Ende A, Tan PS, et al. Smoking and COVID-19 results: an observational and Mendelian randomized study using the UK Biobank cohort by Thorax First published online: September 27, 2021. doi: 10.1136 / thoraxjnl-2021- 217080

Commentary

This study reveals conflicting evidence from previous studies investigating the association of smoking on the risk and severity of COVID-19.

UKBiobank was used to conduct a large observational, Mendelian randomized (MR) analysis.

This resulted in 421,469 eligible participants, 1649 confirmed infections, 968 COVID-19 related hospitalizations, and 444 COVID-19 related deaths.

And compared with never smokers, current smokers reported a higher risk of hospitalization and death, 5.91, 95% CI 3.66-9.54; 20+ /day, 6.11, 95% CI 3.59-10.42.

In an MR analysis of 281,105 Caucasian participants, a genetically predicted propensity to start smoking was associated with a higher risk of infection, hospitalization.

The higher the genetically predicted number of cigarettes smoked per day, the higher the risk of all outcomes seemed to be.