Alqahtani JS, Oyelade T, Aldhahir AM et al.
PLoS ONE 2020 15(5): e0233147. https://doi.org/10.1371/journal.pone.0233147
There is a debate about the influence of smoking on morbidity and mortality associated with infection with COVID-19. The authors searched electronic databases from inception to March 24, 2020 extracting data by two independent authors in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Study quality was assessed using a modified version of the Newcastle-Ottawa Scale. They conducted a meta-analysis using a random-effects model to calculate pooled prevalence rates and 95% confidence intervals (95%CI).
123 abstracts were screened and 61 full-text manuscripts were reviewed with 15 studies meeting the inclusion criteria, which included a total of 2473 confirmed COVID-19 patients. The crude case fatality rate of COVID-19 was 7.4%. The pooled prevalence rates of COPD patients and smokers in COVID-19 cases were 2% (95% CI, 1%–3%) and 9% (95% CI, 4%–14%) respectively. COPD patients were at a higher risk of more severe disease (risk of severity = 63%, (22/35) compared to patients without COPD 33.4% (409/1224) [calculated RR, 1.88 (95% CI, 1.4–2.4)]. This was associated with higher mortality (60%). 22% (31/139) of current smokers and 46% (13/28) of ex-smokers had severe complications. The calculated RR showed that current smokers were 1.45 times more likely [95% CI: 1.03–2.04] to have severe complications compared to former and never smokers. Current smokers also had a higher mortality rate of 38.5%
The authors conclude that COVID-19 infection was associated with substantial severity and mortality rates in COPD. Compared to former and never smokers, current smokers were at greater risk of severe complications and higher mortality rate.