In a new study, researchers found that cumulative cigarette smoke exposure is a big risk factor for hospital admission and death from COVID-19.
The research was conducted by a team from Cleveland Clinic Lerner College of Medicine.
In the study, the team evaluated the link between cumulative smoking exposure, as measured by pack-years, and the outcomes for 7,102 patients who tested positive for COVID-19.
The researchers found that 84.8% were never smokers, 2.4% were current smokers, and 12.8% were former smokers.
There was a dose-response association between pack-years and adverse COVID-19 outcomes.
Patients who smoked for more than 30 pack-years having 2.25 times higher risks of hospitalization and 1.89 times higher risks of dying following a COVID-19 diagnosis versus never smokers.
Similar risks were seen for both current and former smokers.
The team says that smoking is imperfectly classified in patient electronic medical records, and former smokers are potentially classified as never smokers, while pack-years may be under-recorded.
But this misclassification is likely to bias the present results and underestimate the link between cigarette smoking and adverse COVID-19 outcomes.
One author of the study is Katherine E. Lowe.
The study is published in JAMA Internal Medicine.
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