Smokers are 60% to 80% more likely to be admitted to hospital with Covid-19 and also more likely to die from the disease, the data suggests.
TO study, which combined genetic and observational data on smoking and Covid-19 to strengthen the evidence base, contradicts research published at the start of the pandemic suggesting that smoking could help protect against the virus. This was later withdrawn after some of the article’s authors were found to have financial ties to the tobacco industry.
Other studies on whether smoking is associated with a higher chance of a more serious Covid-19 infection have produced inconsistent results.
One problem is that most of these studies have been observational, making it difficult to establish whether smoking is the cause of increased risk, or whether there is another blame, such as smokers more likely to come from a lower socioeconomic background.
Oxford University’s Dr Ashley Clift and colleagues relied on GP health records, Covid-19 test results, hospital admissions data, and death certificates to identify associations between the Smoking and Covid-19 severity from January to August 2020 in 421,469 UK Biobank participants. study, all of which had also been previously analyzed for their genetic makeup.
Compared to those who had never smoked, current smokers were 80% more likely to be admitted to the hospital and significantly more likely to die from Covid-19 if they became infected.
To investigate, Clift and her team used a technique called Mendelian randomization, which uses genetic variants as surrogates for a particular risk factor, in this case genetic variants that help determine whether someone is more likely to smoke or smoke heavily, to gain more. tests. for a causal relationship.
Although the contribution of each of these variants is small and it is not necessarily understood why they increase a person’s chances of being a smoker, they avoid many of the limitations of observational studies and therefore help to provide a clearer picture. whether there is a biological link between smoking and Covid-19.
“The study adds to our confidence that tobacco smoking does not protect against Covid-19, as its Mendelian randomization analyzes are less susceptible to confusion than previous observational studies,” wrote Dr. Anthony Laverty and Professor Christopher Millett of the Imperial College London in a linked publisher published in Thorax magazine.
Mendelian randomisation analysis also supported the link between smoking and worse Covid-19 outcomes, and found that a genetic predisposition to smoking was associated with a 45% increased risk of infection and a 60% increased risk of hospital admission for Covid-19.
A genetic predisposition to heavy smoking was associated with more than double the risk of infection; a five-fold increase in the risk of hospital admission; and a 10-fold increase in the risk of death from the virus, the team found.
Clift said: “Our results strongly suggest that smoking is related to your risk of getting severe Covid, and just as smoking affects your risk of heart disease, different cancers and all those other conditions that we know smoking is related to, it appears to be. same for Covid. So now could be as good a time as any to quit and quit smoking. “