Preprint Review Version 1 Preserved in Portico This version is not peer-reviewed

What is Happening with Smokers and COVID-19? A Systematic Review and a Meta-Analysis

Version 1 : Received: 30 April 2020 / Approved: 30 April 2020 / Online: 30 April 2020 (17:01:38 CEST)

A peer-reviewed article of this Preprint also exists.

González-Rubio, J.; Navarro-López, C.; López-Nájera, E.; López-Nájera, A.; Jiménez-Díaz, L.; Navarro-López, J.D.; Nájera, A. A Systematic Review and Meta-Analysis of Hospitalised Current Smokers and COVID-19. Int. J. Environ. Res. Public Health 2020, 17, 7394. González-Rubio, J.; Navarro-López, C.; López-Nájera, E.; López-Nájera, A.; Jiménez-Díaz, L.; Navarro-López, J.D.; Nájera, A. A Systematic Review and Meta-Analysis of Hospitalised Current Smokers and COVID-19. Int. J. Environ. Res. Public Health 2020, 17, 7394.

Journal reference: Int. J. Environ. Res. Public Health 2020, 17, 7394
DOI: 10.3390/ijerph17207394

Abstract

SARS-CoV-2 is a new coronavirus that has caused a worldwide pandemic. It produces severe acute respiratory disease (COVID-19), which is fatal in many cases, characterised by cytokine release syndrome (CRS). According to the World Health Organization (WHO), those who smoke are likely to be more vulnerable to infection. Here, in order to clarify the epidemiologic relationship between smoking and COVID-19, we present a systematic literature review until 28 April 2020 and a meta-analysis. It includes 18 recent COVID-19 clinical and epidemiological studies based on smoking patient status from 720 initial studies in China, USA, and Italy. The percentage of hospitalised current smokers was 7.7% (95%CI: 6.9-8.4) in China, 2.3% (95%CI: 1.7-2.9) in the USA and 7.6% (95%CI: 4.2-11.0) in Italy. These percentages were compared to the smoking prevalence of each country and statistically significant differences were found in them all (p <0.0001). By means of the meta-analysis, we offer epidemiological evidence showing that smokers were statistically less likely to be hospitalised (OR=0.18, 95%CI: 0.14-0.23, p<0.01). CRS and exacerbated inflammatory response are associated with aggravation of hospitalise patients. In this scenario, we hypothesise that nicotine, not smoking, could ameliorate the cytokine storm and severe related inflammatory response through the cholinergic-mediated anti-inflammatory pathway.

Subject Areas

cholinergic anti-inflammatory pathway; novel coronavirus; SARS-CoV-2; COVID-19; meta-analysis; Cytokine Release Syndrome; nicotine; smokers

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