Study Shows a Dose-Response Association Between Cigarette Pack-Years, Adverse COVID-19 Outcomes

January 26, 2021

By Denise Baez

Cumulative exposure to cigarette smoke is an independent risk factor for hospital admission and death from coronavirus disease 2019 (COVID-19), according to a study published in JAMA Internal Medicine.

In a study of 7,102 patients who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between March 8, 2020, and August 25, 2020, those who smoked >30 pack-years (n = 341) had a 2.25 times higher odds of hospitalisation compared with never smokers (n = 6,020), after adjusting for age, race, and gender.

In addition, patients who smoked >30 pack-years were 1.69 times more likely to require admission to the intensive care unit (ICU) and 1.89 times more likely to die following a COVID-19 diagnosis compared with never smokers.

Compared with never smokers, those who smoked 10 to 30 pack-years were 1.41 times more likely to require hospitalisation, 1.55 times more likely to be admitted to the ICU, and 1.47 times more likely to die.

“The findings showed a dose-response association between pack-years and adverse COVID-19 outcomes,” wrote Joe Zein, MD, Cleveland Clinic, Cleveland, Ohio, and colleagues, noting that the association is likely mediated in part by comorbidities.

Among patients who smoked >30 pack-years, 85.5% had hypertension, 47.2% had chronic obstructive pulmonary disease or emphysema, 43.1% had diabetes, 43.1% had coronary heart disease, 32.3% had heart failure, 30.8% had cancer or a history of cancer, and 22.9% had asthma. Among never smokers, these rates were 37.6%, 2.6%, 16.7%, 7%, 5.8%, 9.7%, and 15.7%. Never smokers had a mean age of 47.8 years compared with 71 years in those who smoked >30 pack-years.

“The results of this study suggest that cumulative exposure to cigarette smoke is an independent risk factor for hospital admission and death from COVID-19,” the authors concluded. “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. However, this misclassification is likely to bias the present results toward the null, which would underestimate the association of cigarette smoking on adverse COVID-19 outcomes.”


SOURCE: JAMA Internal Medicine