Clinical trial NCT04915781: Tobacco Use and COVID-19 Incidence in the Finnish General Population
Official title: Tobacco Use and Incidence of SARS-CoV-2 Infection in the Finnish General Population
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: SARS-CoV-2 Infection
Covid19
Keywords: Tobacco use
SARS-CoV-2
COVID-19
Epidemiology
Cohort Studies
Incidence
Lead sponsor: Finnish Institute for Health and Welfare
Sponsor class: OTHER_GOV
Collaborators: name: Karolinska Institutet
name: Norwegian Institute of Public Health
First posted: 2021-06-07
Enrollment: 60872
Sex: ALL
Minimum age (years): 20
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: PROBABILITY_SAMPLE
Study population: Permanent residents in Finland aged 20 and over who participated in the FinSote surveys in 2018, 2019 and 2020. These are general population samples representative of the Finnish population. The sampling frame was the Population Register (in 2020 the Digital and Population Data Services Agency, created after the merge between the Population Register of Statistics Finland and local register offices), which includes all individuals residing permanently in Finland, including conscripts and people living in institutions.

Brief summary: This is an observational study of participants in three general population health surveys (FinSote 2018, 2019, 2020) who are followed up until the incidence of SARS-CoV-2 infection or end of follow-up. The primary objective is to examine the association between tobacco use and the risk of SARS-CoV-2 infection in a general population sample in Finland.

Detailed description: Tobacco use, as a leading risk factor of death and disability due to respiratory diseases, was expected to increase the risk of SARS-CoV-2 infection and COVID-19 deaths. Earlier epidemiological studies, however, showed that smokers were underrepresented among patients hospitalized due to COVID-19. The most recent meta-analysis has confirmed these early findings, showing that current smokers had lower risk of SARS-CoV-2 infection than never smokers (Relative risk 0.71, 95% Credible interval 0.61; 0.82). A majority of these studies are based on samples of hospitalized patients, tested population or specific population groups, which might not represent the general population. In addition, data on tobacco use has been primarily collected from electronic health records or retrospectively and therefore prone to misclassification and information bias.

A message of a protective effect of tobacco use could undermine public health efforts to curb its use and reduce the perception of harm in the general population. Studies with general population samples and prospective data collection are thus urgently needed.

The aim of the study is to examine the association between tobacco use and the risk of SARS-CoV-2 infection. We will explore several forms of tobacco use (smoking, moist smokeless tobacco and e-cigarettes) and investigate whether introducing a potential collider bias by adjusting for mediating risk factors (alcohol use, physical activity and obesity) could have explained earlier results. We will use data from a prospective cohort study of nationally representative health surveys in Finland linked to SARS-CoV-2 incidence data, which is less subject to collider and recall bias than previous case-control studies.

Eligibility criteria: Inclusion Criteria:

* Permanent residents of Finland
* Registered in the Population Register at the moment of sampling
* Aged 20 and over
* Participated in the FinSote surveys in 2018, 2019 or 2020

Exclusion Criteria:

* Temporary residents in Finland or tourists
* Age less than 20 years old
* Did not participate in FinSote surveys in 2018, 2019 and 2020

Primary outcomes:
measure: Incidence of SARS-CoV-2 infection
timeFrame: Baseline until SARS-CoV-2 infection or April 30, 2021
Secondary outcomes:
Other outcomes:
Locations:
city: Helsinki
country: Finland
facility: Finland
Study officials:
affiliation: Finnish Institute for Health and Welfare
name: Sakari Karvonen, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Simons D, Shahab L, Brown J, Perski O. The association of smoking status with SARS-CoV-2 infection, hospitalization and mortality from COVID-19: a living rapid evidence review with Bayesian meta-analyses (version 7). Addiction. 2021 Jun;116(6):1319-1368. doi: 10.1111/add.15276. Epub 2020 Nov 17.
citation: Bar-Zeev Y. Commentary on Simons et al. Public health implications of the suggested association between nicotine, smoking and infection with SARS-CoV-2. Addiction. 2021 Jun;116(6):1369-1370. doi: 10.1111/add.15356. Epub 2020 Dec 25. No abstract available.
citation: Griffith GJ, Morris TT, Tudball MJ, Herbert A, Mancano G, Pike L, Sharp GC, Sterne J, Palmer TM, Davey Smith G, Tilling K, Zuccolo L, Davies NM, Hemani G. Collider bias undermines our understanding of COVID-19 disease risk and severity. Nat Commun. 2020 Nov 12;11(1):5749. doi: 10.1038/s41467-020-19478-2.
citation: Haddad C, Bou Malhab S, Sacre H, Salameh P. Smoking and COVID-19: A Scoping Review. Tob Use Insights. 2021 Feb 15;14:1179173X21994612. doi: 10.1177/1179173X21994612. eCollection 2021.
citation: Tattan-Birch H, Marsden J, West R, Gage SH. Assessing and addressing collider bias in addiction research: the curious case of smoking and COVID-19. Addiction. 2021 May;116(5):982-984. doi: 10.1111/add.15348. Epub 2021 Jan 20. No abstract available.
citation: van Westen-Lagerweij NA, Meijer E, Meeuwsen EG, Chavannes NH, Willemsen MC, Croes EA. Are smokers protected against SARS-CoV-2 infection (COVID-19)? The origins of the myth. NPJ Prim Care Respir Med. 2021 Feb 26;31(1):10. doi: 10.1038/s41533-021-00223-1.
citation: Vardavas CI, Nikitara K. COVID-19 and smoking: A systematic review of the evidence. Tob Induc Dis. 2020 Mar 20;18:20. doi: 10.18332/tid/119324. eCollection 2020.
citation: Jimenez-Ruiz CA, Lopez-Padilla D, Alonso-Arroyo A, Aleixandre-Benavent R, Solano-Reina S, de Granda-Orive JI. [COVID-19 and Smoking: A Systematic Review and Meta-Analysis of the Evidence]. Arch Bronconeumol. 2021 Jan;57:21-34. doi: 10.1016/j.arbres.2020.06.024. Epub 2020 Jul 25. Spanish.