Smoking and Risk of Negative Outcomes Among COVID-19 Patients: A Systematic Review and Meta-Analysis

Abstract

Background/Aims: COVID-19 has major effects on the clinical, humanistic, and economic outcomes among patients, particularly having severe symptoms or death. Smoking has been reported as one of the factors that increases severity and mortality rate among COVID-19 patients. However, the effect of smoking on such medical outcomes is still controversial. This study aims to conduct a systematic review and a meta-analysis (SR/MA) of the association between smoking and negative outcomes among COVID-19 patients. Method: Electronic databases, including PubMed, EMBASE, Cochrane Library, Science Direct, Google Scholar, were systematically searched, from the start of the database until 20 May 2020, for relevant published articles on smoking and COVID-19. All relevant studies were screened using a set of inclusion and exclusion criteria. The Newcastle–Ottawa Scale was used to assess the methodological quality of eligible articles. Random meta-analyses were conducted to estimate the odds ratio [OR] with 95% confidence interval [95%CI]. Publication bias was assessed using the funnel plot, Begg's test and Egger's test. All steps of SR/MA in this study were in line with PRISMA statement. The study protocol was registered with PROSPERO (CRD42020186638). Findings: A total of 510 studies were retrieved and reviewed and a final thirteen studies were included for meta-analysis. Both current smoking and former smoking can significantly increase the risk of disease severity (OR 1·51; 95% CI 1·06-2·15, p= 0·023, and OR 3·73; 95%CI 2·56-5·42, p Interpretations: Our meta-analysis demonstrated that smoking significantly increases the risk of disease severity and tend to increase the risk of death. Further prospective studies exploring the underlying mechanisms of this association is warranted. Funding Support This research project was supported by Unit of Excellence on Clinical Outcomes Research and IntegratioN (UNICORN), University of Phayao [Grant Number: UoE62003].Declaration of Interests: The authors declare that they have no competing interests.Ethics Approval Statement: Not applicable.