Smokers at higher risk of COVID-19 death, particularly in low and middle income countries

Roengrudee Patanavanich, Tanatorn Siripoon, Salin Amponnavarat and I just published “Active smokers are at higher risk of COVID-19 death: A systematic review and meta-analysis” that finds that, among people diagnosed with COVID-19 both current and former smokers are at increased risk of death from COVID-19. This paper takes advantage of the growing number of studies to better separate former smokers from never smokers than was possible in earlier meta-analyses.

This paper also refines our earlier meta-analysis to find that the risks of death are higher among younger former but not current smokers. It also finds higher COVID risks associated with smoking in low and middle income countries.

Here is the abstract:

Introduction: Current evidence indicates that smoking worsens COVID-19 outcomes. However, when studies restricted their analyses to current smokers, the risks for COVID-19 severity and death are inconsistent. This meta-analysis explored the association between current smoking and the risk for mortality based on the studies that reported all three categories of smoking (current, former, and never smokers) to overcome the limitation of the previous meta-analyses which former smokers might have been classified as non-smokers.

Methods: We searched PubMed and Embase up to 1 January 2021. We included studies reporting all three categories of smoking behaviors of COVID-19 patients and mortality outcomes. A random-effects meta-analysis and meta-regression were used to examine relationships in the data. 

Results: A total of 34 articles with 35,193 COVID-19 patients was included. The meta-analysis confirmed the association between current smoking (OR 1.26, 95% CI: 1.01-1.58) and former smoking (OR 1.76, 95% CI: 1.53-2.03) with COVID-19 mortality. We also found that the risk for COVID-19 death in current smokers does not vary by age, but significantly drops by age in former smokers. Moreover, current smokers in non-high-income countries have higher risks of COVID-19 death compared with high-income countries (OR 3.11, 95% CI: 2.04-4.72 vs. OR 1.14, 95% CI: 0.91-1.43; p=0.015).   

Conclusions: Current and former smokers are at higher risk of dying from COVID-19. Tobacco control should be strengthened to encourage current smokers to quit and prevent the initiation of smoking. Public health professionals should take the COVID-19 pandemic as an opportunity to promote smoking prevention and cession.

Implications: This study makes an important contribution to the existing literature by distinguishing between current and former smoking and their separate effects on COVID-19 mortality. We also explore the effects by age of patients and country income level. Findings from this study provide empirical evidence against misinformation about the relationship between smoking and COVID-19 mortality.

The full citation is: Patanavanich R, Siripoon T, Amponnavarat S, Glantz SA. Active smokers are at higher risk of COVID-19 death: A systematic review and meta-analysis. Nicotine Tob Res. 2022 Apr 1:ntac085. doi: 10.1093/ntr/ntac085. Epub ahead of print. PMID: 35363877. It is available here.

Published by Stanton Glantz

Stanton Glantz is a retired Professor of Medicine who served on the University of California San Francisco faculty for 45 years. He conducts research on tobacco and cannabis control and cardiovascular disease/

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