Increased cumulative exposure to cigarette smoke is an independent risk factor for hospital admission and death from coronavirus disease 2019 (COVID-19), according to the results of a cohort study published in JAMA Internal Medicine that identified a dose-response relationship between pack-years and adverse COVID-19 outcomes. A significantly greater risk for hospitalization or death was identified in patients who smoked more than 30 pack-years.

There are limited data suggesting that smoking status may be associated with poor outcomes with COVID-19; the aim of the study was to determine if smoking exposure influences COVID-19-related hospitalization and mortality.

The study evaluated data from 7102 patients in the Cleveland Clinic health system’s COVID-19 registry who tested positive for SARS-CoV-2 within between March 8, 2020 and August 25, 2020. Most patients (84.8%) had no smoking history, 2.4% were current smokers, and 12.8% were former smokers. Patients who were current or former smokers were stratified according to cumulative smoking history: 0 to 10 pack-years, 10 to 30 pack-years, and more than 30 pack-years.

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Smokers had a heightened risk for hospitalization from COVID-19 that increased in a dose-response manner. When adjusted for age, race, and gender, the odds of hospitalization were 0.99 (95% CI, 0.76-1.30) for 0 to 10 pack-years, 1.41 (95% CI, 1.12-1.78) for 10 to 30 pack-years, and 2.25 (95% CI, 1.76-2.88) for more than 30 pack-years.

However, after adjustment for age, race, gender, medication, and comorbidity, a significantly higher risk for hospitalization remained only for patients with a more than 30 pack-year smoking history (odds ratio [OR], 2.19; 1.52-3.14).

The risk for intensive care unit (ICU) admission and death demonstrated similar dose-response relativity to increasing pack-years. When adjusted for age, race, and gender, the odds for ICU admission were 1.19 (95% CI, 0.75-1.89) for 0 to 10 pack-years, 1.55 (95% CI, 1.09-2.21) for 10 to 30 pack-years, and 1.69 (95% CI, 1.23-2.35) for more than 30 pack-years. For death, the odds were 1.66 (95% CI, 0.98-2.83), 1.47 (95% CI, 0.96-2.27), and 1.89 (95% CI, 1.29-2.76) for 0 to 10, 10 to 30, and more than 30 pack-years, respectively.

The risk for ICU admission or death was not significant for any pack-year group compared with never smokers when adjusted for medication and comorbidities.

“This single central registry of patients who tested positive for COVID-19 that increased cumulative smoking was associated with higher risk of hospitalization and mortality from COVID-19 in a dose-dependent manner,” the study authors concluded.

Disclosures: One of the study authors disclosed financial relationships with the pharmaceutical industry and/or the medical device industry. For a full list of disclosures, please refer to the original study.


Lowe KE, Zein J, Hatipoğlu U, Attaway A. Association of smoking and cumulative pack-year exposure with COVID-19 outcomes in the Cleveland Clinic COVID-19 Registry. JAMA Intern Med. Published online ahead of print January 25, 2021. doi:10.1001/jamainternmed.2020.8360