Correlation between prevalence of tobacco smoking and risk and severity of COVID-19 at the national level in the European Union: an ecological study

  1. Adrián González-Marrón
  2. Jose M Martínez-Sánchez

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Abstract

The Angiotensin-converting enzyme 2 (ACE2) protein is the receptor for different coronaviruses, including Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus disease 2019 (COVID-19). Previous studies suggested the hypothesis that nicotine could downregulate the expression of the ACE2. Due to the high level of nicotine intake, the objective of this preliminary study was to assess, at the ecological level, the correlation between tobacco smoking and the attack rate and severity of COVID-19 in the European Union (EU). We have found that there is a statistically significant negative correlation between the age-standardized prevalence of tobacco smoking and the attack rate of COVID-19 in member states of the EU [Spearman’s correlation coefficient = −0.476 (95% confidence interval −0.117, −0.725) (p-value = 0.012)], meaning that in member states with a higher age-standardized prevalence of tobacco smoking the attack rate of COVID-19 has been so far lower. Further research is needed to understand the possible effect of nicotine exposure in the expression of the ACE2 protein.

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  1. ScreenIT

    SciScore for 10.1101/2020.04.28.20083352: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: Thank you for sharing your code and data.

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    This study contains some limitations, which should be addressed. Firstly, this is an ecological study, meaning that conclusions at the individual level should not be drawn. Also, data are still preliminary due to the outbreak being still ongoing and adjustment for confounders was not possible (public health measures such as lockdowns, population density of the member states, etc.). Besides, quality and accuracy of numbers on COVID-19 cases and deaths may vary between member states due to differences in capacities in national surveillance systems and definitions of case and death. In conclusion, with data available as of April 14th 2020, and at the ecological level, in the member states of the EU with higher rates of smoking, the attack rate of COVID-19 has been lower. In this sense, further research is needed to understand the possible effect of nicotine exposure in the expression of the ACE2 protein, and eventually in the outcomes of COVID-19.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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  2. Version published to 10.1101/2020.04.28.20083352 on medRxiv