Smoking is Associated with COVID-19 Progression: A Meta-Analysis

Objective

To determine the association between smoking and progression of COVID-19.

Design

A meta-analysis of 12 published papers.

Data Source

PubMed database was searched on April 6, 2020.

Eligibility criteria and data analysis

We included studies reporting smoking behavior of COVID-19 patients and progression of disease. Search terms included “smoking”, “smoker*”, “characteristics”, “risk factors”, “outcomes”, and “COVID-19”, “COVID”, “coronavirus”, “sar cov-2”, “sar cov 2”. There were no language limitations. One author extracted information for each study, screened the abstract or the full text, with questions resolved through discussion among both authors. A random effects meta-analysis was applied.

Main Outcome Measures

The study outcome was progression of COVID-19 among people who already had the disease.

Results

We identified 12 papers with a total of 9,025 COVID-19 patients, 878 (9.7%) with severe disease and 495 with a history of smoking (5.5%). The meta-analysis showed a significant association between smoking and progression of COVID-19 (OR 2.25, 95% CI 1.49-3.39, p=0.001). Limitations in the 12 papers suggest that the actual risk of smoking may be higher.

Conclusions

Smoking is a risk factor for progression of COVID-19, with smokers having higher odds of COVID-19 progression than never smokers. Physicians and public health professionals should collect data on smoking as part of clinical management and add smoking cessation to the list of practices to blunt the COVID-19 pandemic.

What is already known on this topic

• Smoking increases risk and severity of pulmonary infections because of damage to upper airways and a decrease in pulmonary immune function.

What this study adds

• Smoking is associated with COVID-19 severity.

• Smoking history should be part of clinical management of COVID-19 patients and cessation should be added to the list of practices to blunt the COVID-19 pandemic.