Smoking is Associated with Doubling of COVID-19 Progression Risk

There are a lot of reasons to expect that smoking would make COVID-19 worse.  Kade Patanavanich and I have completed a meta-analysis of 12 papers that present evidence on disease progression among people who have been diagnosed with COVID, 10 from China, 1 from Korea, and 1 from the USA.  We found that the odds of disease progression were more than doubled.

These papers all have limitations, most notably the fact that they are almost certainly missing a lot of smokers in their patient histories. This limitation will lead to the risk being underestimated.

The paper reporting these results is now under peer review.  Consistent with the urgency of the situation and the general policies of a growing number of journals that pre-prints of papers be made available during the peer review process, we have posted our manuscript to the medRxiv preprint server here.

Here is the abstract:

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.

The full citation is:  Roengrudee Patanavanich, Stanton A Glantz Smoking is Associated with COVID-19 Progression: A Meta-Analysis.  doi: https://doi.org/10.1101/2020.04.13.20063669