COPD worsens COVID-19, especially among smokers

The coronavirus disease 2019 (COVID-19) worsens outcomes in patients with chronic obstructive pulmonary disease (COPD), especially in current smokers, according to a new meta-analysis.

“Despite the low prevalence of COPD and smoking in COVID-19 cases, this result emphasizes attention to effective preventive measures to support reducing the burden of COVID-19 in these vulnerable populations. This has the potential to improve outcomes for patients and lessen the burden on health services,” researchers said.

Accessing the databases of Medline and Google Scholar, researchers retrieved 15 studies that satisfied the selection criteria, yielding a cumulative total of 2,473 confirmed COVID-19 patients. Most of the studies were retrospective in design and conducted in China; only one study was from the United States. The overall risk of bias was low. [PLoS One 2020;15:e0233147]

COPD appeared to be a rare comorbidity, with only 58 COVID-19 patients receiving the diagnosis, yielding a prevalence rate of 2.3 percent.

However, COPD appeared to worsen COVID-19 severity. Seven of the included studies contributed 35 COPD patients, of whom 63 percent (n=22) had severe COVID-19, while only 37 percent had nonsevere infections. The resulting risk estimate was statistically significant.

Moreover, two studies with 10 COPD patients showed that COVID-19 mortality rate was 60 percent in those with the comorbidity, as opposed to 55 percent in those without.

“To the best of our knowledge, this is the first systematic review and meta-analysis to develop an informed understanding of the prevalence, severity and mortality of COPD patients diagnosed with COVID-19,” the researchers said.

“Although the COPD prevalence was not high in the included confirmed COVID-19 cases, COVID-19 causes a substantial burden on COPD patients with increased disease severity,” which is in consonance with other results in preprints. [medRxiv 2020;doi: 10.1101/2020.02.25.20027664]

The researchers also evaluated the potential effects of smoking. In eight studies with 221 confirmed COVID-19 patients, the overall pooled prevalence of current smoking was 9 percent. Severe complications were common among current (22.30 percent) and former (46 percent) smokers.

However, risk analysis found that the likelihood of developing severe COVID-19 complications was 45-percent higher in current smokers than in never- and former smokers. There was also a 38.5-percent excess in mortality risk among current smokers.

“The impact of smoking history on vulnerability to COVID-19 has been explored, but there is limited data on the contribution of tobacco smoking to the spread of and poor outcome in COVID-19,” the researchers said, pointing out evidence from other respiratory virus which suggests that smoking may worsen outcomes and intensify transmission. [Am J Respir Cell Mol Biol 2009;41:189-198]

“We strongly advocate public awareness campaigns concentrating on ways to achieve smoking cessation among smokers, and it is possible that an improvement in cessation rates will help to reduce the spread of SARS-CoV-2,” they added. “Future studies should investigate the mechanisms between COPD, smoking and COVID-19 infection.”