Covid19NCT04896918
Tobacco Use and the Risk of COVID-19
An observational study of Covid19, run by Karolinska Institutet.
Trial summary
Contrasting hypotheses, including that of a protective role of nicotine, have been generated concerning the association between smoking and the occurrence of COVID-19 infection. The question has attracted a lively scientific and public debate. Read more about this study
- Who is it for?
- Ages 23 years and older
- Conditions the study is for
- Covid19
- What is being tested?
- Tobacco use
- Type of treatment
- Lifestyle or therapy programme
- How many people
- 450,000 participants
- Where
- No sites listed yet
- Study dates
- 1 Oct 2015to 31 Dec 2023
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 23 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult clients of the public dental clinics in Stockholm Region (Sweden) in the period between October 2015 and January 2020.
Who may be able to join
- Being a client of the public dental clinics in the region of Stockholm (Sweden) between October 2015 and January 2020
- Being age 23 years or older
- Having tobacco use habits recorded in at least one visit
Who cannot join
- Not having a Swedish personal identity number
- Resident in assisted elderly dwelling
About this study
Official title: Smoking, Snus Use and the Risk of COVID-19 in a Cohort of Adult Client of Public Dentistry Clinics: is There a Causal Association?
Contrasting hypotheses, including that of a protective role of nicotine, have been generated concerning the association between smoking and the occurrence of COVID-19 infection. The question has attracted a lively scientific and public debate. However, the studies conducted so far are based on clinical samples, with a majority of hospital case series, thus most likely suffering from bias due to selection.
The investigators propose to conduct an analysis of the potential causal association between smoking or the use of the Swedish smokeless tobacco snus and the occurrence of COVID-19 using data from a newly identified retrospective cohort in Sweden. Information on tobacco use will be extracted by public dental clinic records in Stockholm Region between October 2015 and January 2020. Information on diagnoses of COVID-19 will be obtained through record linkage with health care registers of inpatient and outpatient care during the period February 2020-August 2021. Socio-demographic information will be accrued from the register of the total population in Stockholm Region (Statistics Sweden). The risk of COVID-19 for tobacco users compared to non-tobacco users will be calculated as a measure of association adjusting for potential confounders.
Read the detailed description
Background The role of tobacco use in the incidence and in the prognosis of the Severe acute respiratory syndrome-Cov2 disease (COVID-19 pandemic) has raised much international interest, due to contrasting findings reported so far in the scientific literature. On one side smoking may increase the risk of adverse outcomes in clinically overt COVID-19 requiring hospital admission. Several cross-sectional studies (case series) indicated a higher risk of negative disease progression among smokers compared to non-smokers in cases hospitalized with severe symptoms of the disease. On the other side, studies also suggest also that smoking is associated with a decreased risk of hospital admission with a diagnosis of COVID-19, or a decreased risk of occurrence of the disease in the community. These studies have noted 4 to 5 times lower proportions of smokers among patients hospitalized for COVID-19 compared with the underlying source population. A metanalysis of hospital case series confirmed this gap.
Given the public health importance of tobacco use as a risk factor for morbidity and mortality, it is urgent to provide both the scientific and the broad lay community with sound information from large population studies, something that the World Health Organization has also recommended.
Aim The present study aims to elucidate the potential causal association between tobacco use (smoking and snus) and COVID-19 using a population-based cohort study.
Methods In Sweden, the public dental clinics collect information at each visit on lifestyle and co-morbidities with relevance for oral health (health declaration), with a uniform instrument in use from October 2015. Smoking and snus use are ascertained as past use, current use and categories of intensity of current use. During February 2020 the usual routine activity of the clinics was disrupted by the pandemic, and the so-called oral health check-up was discontinued. About 450 000 adult clients of the public dentistry in Stockholm Region were identified in the period October 2015 to January 2020. Among these about 120000 were assessed within 7 months from the onset of the pandemic, therefore represent recent experiences. The investigators expect about 9% to be smokers and about 11% to be snus users. With the help of the national personal numbers assigned to every resident in Sweden at birth or at immigration, the investigators will link the reports of smoking among these clients with diagnoses of COVID-19 and other comorbidities registered in the regional database of inpatient and outpatient health care. The information in the dental clinic registers will be linked to the total population of the region of Stockholm, in order to extract socio-demographic information.
Statistical analysis plan The investigators will examine the role of tobacco use on the risk of the following events: any diagnosis of COVID-19, hospitalization, receiving intensive care, and death because of COVID-19 using generalized linear models, with and without possible confounders (age, gender, country of birth, type of employment, education and cohabitation), and within subgroups to identify potential effect modification (age group, gender [in analyses of snus use], assumed infection risk associated to occupation, pandemic period, and strategies of virologic testing, very restricted in the first 3 months, available on individual request thereafter).
- Conditions
- Covid19
- Being tested
- Tobacco use
- Keywords
- Tobacco, Snus, COVID-19
- Medical subject headings
- COVID-19
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Tobacco useBehavioural
| Study group | Role | What they receive |
|---|---|---|
| Cohort of adult client of public dental clinics in Region Stockholm | Tobacco use (cigarette smoking and/or snus use) will be considered as exposure. Information on tobacco use will be extracted by public dental clinic records in Stockholm Region (October 2015-January 2020). Any diagnosis of COVID-19, hospitalization, receiving intensive care, and death because of COVID-19 will be examined as outcomes. Diagnoses of COVID-19 will be obtained through record linkage with health care registers of inpatient and outpatient care (February 2020-August 2021). Receives: Behavioral: Tobacco use |
What is being measured
The primary outcome is the main question the study is designed to answer.
Diagnosis of COVID-19
Incident diagnoses of COVID-19, whether symptomatic or not, corresponding to a positive virologic test (PCR)
Measured: 18 months from the index case of the pandemic in Sweden
Hospital admission for COVID-19
Rates of hospital admission due to COVID-19 reported in the hospital register
Measured: 18 months from the index case of the pandemic in Sweden
Intensive unit care because of a diagnosis of COVID-19
Rates of admission to Intensive care units (IU) with a diagnosis of COVID-19 reported in the hospital register
Measured: 18 months from the index case of the pandemic in Sweden
Death for COVID-19
COVID-19 death rates where COVID-19 is mentioned as cause of death reported in the death register
Measured: 18 months from the index case of the pandemic in Sweden
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 May 2021
- Study start1 Oct 2015
- Primary completion31 Dec 2023
- Study completion31 Dec 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (6)Papers the sponsor has linked to this study.
- Other trials for Covid19Studies of the same condition, open and under way.
- More trials run by Karolinska InstitutetThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Retrospective
- Enrolment
- 450,000 participants (actual)
Sponsor and investigators
- Lead sponsor
- Karolinska Institutet
- Sponsor type
- University, hospital or other
- Collaborators
- Region Stockholm, Norforsk, Norwegian Institute of Public Health, Finnish Institute for Health and Welfare
- Responsible party
- Principal investigator, Maria Rosaria Galanti, Karolinska Institutet
- Investigators
- Maria Rosaria Galanti, PhD, Principal investigator, Karolinska Institutet
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04896918
- Sponsor's protocol ID
- 4-1457/2021
- Status last verified
- Mar 2024
- First submitted
- 20 May 2021
- Last updated
- 6 Mar 2024
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Guan WJ, Ni ZY, Hu Y, Liang WH, Ou CQ, He JX, Liu L, Shan H, Lei CL, Hui DSC, Du B, Li LJ, Zeng G, Yuen KY, Chen RC, Tang CL, Wang T, Chen PY, Xiang J, Li SY, Wang JL, Liang ZJ, Peng YX, Wei L, Liu Y, Hu YH, Peng P, Wang JM, Liu JY, Chen Z, Li G, Zheng ZJ, Qiu SQ, Luo J, Ye CJ, Zhu SY, Zhong NS; China Medical Treatment Expert Group for Covid-19. Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med. 2020 Apr 30;382(18):1708-1720. doi: 10.1056/NEJMoa2002032. Epub 2020 Feb 28.
PubMed 32109013Zhou F, Yu T, Du R, Fan G, Liu Y, Liu Z, Xiang J, Wang Y, Song B, Gu X, Guan L, Wei Y, Li H, Wu X, Xu J, Tu S, Zhang Y, Chen H, Cao B. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. Lancet. 2020 Mar 28;395(10229):1054-1062. doi: 10.1016/S0140-6736(20)30566-3. Epub 2020 Mar 11.
PubMed 32171076Zhang JJ, Dong X, Cao YY, Yuan YD, Yang YB, Yan YQ, Akdis CA, Gao YD. Clinical characteristics of 140 patients infected with SARS-CoV-2 in Wuhan, China. Allergy. 2020 Jul;75(7):1730-1741. doi: 10.1111/all.14238. Epub 2020 Feb 27.
PubMed 32077115Dreher M, Kersten A, Bickenbach J, Balfanz P, Hartmann B, Cornelissen C, Daher A, Stohr R, Kleines M, Lemmen SW, Brokmann JC, Muller T, Muller-Wieland D, Marx G, Marx N. The Characteristics of 50 Hospitalized COVID-19 Patients With and Without ARDS. Dtsch Arztebl Int. 2020 Apr 17;117(16):271-278. doi: 10.3238/arztebl.2020.0271.
PubMed 32519944Rossato M, Russo L, Mazzocut S, Di Vincenzo A, Fioretto P, Vettor R. Current smoking is not associated with COVID-19. Eur Respir J. 2020 Jun 4;55(6):2001290. doi: 10.1183/13993003.01290-2020. Print 2020 Jun.
PubMed 32350106Farsalinos K, Barbouni A, Niaura R. Systematic review of the prevalence of current smoking among hospitalized COVID-19 patients in China: could nicotine be a therapeutic option? Intern Emerg Med. 2020 Aug;15(5):845-852. doi: 10.1007/s11739-020-02355-7. Epub 2020 May 9.
PubMed 32385628
Study at a glance
From the registry record, last updated by the sponsor on 6 Mar 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Smoking, Snus Use and the Risk of COVID-19 in a Cohort of Adult Client of Public Dentistry Clinics: is There a Causal Association?
- ClinicalTrials.gov ID
- NCT04896918
- Acronym / sponsor ID
- 4-1457/2021
- Conditions
- Covid19
- Keywords
- Tobacco, Snus, COVID-19
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 450,000 participants (actual)
- Lead sponsor
- Karolinska InstitutetUniversity, hospital or other
- Collaborators
- Region Stockholm, Norforsk, Norwegian Institute of Public Health, Finnish Institute for Health and Welfare
- Study start
- 1 Oct 2015 (actual)
- Primary completion
- 31 Dec 2023 (actual)
- Study completion
- 31 Dec 2023 (actual)
- First posted
- 21 May 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Contrasting hypotheses, including that of a protective role of nicotine, have been generated concerning the association between smoking and the occurrence of COVID-19 infection. The question has attracted a lively scientific and public debate. However, the studies conducted so far are based on clinical samples, with a majority of hospital case series, thus most likely suffering from bias due to selection.
The investigators propose to conduct an analysis of the potential causal association between smoking or the use of the Swedish smokeless tobacco snus and the occurrence of COVID-19 using data from a newly identified retrospective cohort in Sweden. Information on tobacco use will be extracted by public dental clinic records in Stockholm Region between October 2015 and January 2020. Information on diagnoses of COVID-19 will be obtained through record linkage with health care registers of inpatient and outpatient care during the period February 2020-August 2021. Socio-demographic information will be accrued from the register of the total population in Stockholm Region (Statistics Sweden). The risk of COVID-19 for tobacco users compared to non-tobacco users will be calculated as a measure of association adjusting for potential confounders.
Detailed description
Background The role of tobacco use in the incidence and in the prognosis of the Severe acute respiratory syndrome-Cov2 disease (COVID-19 pandemic) has raised much international interest, due to contrasting findings reported so far in the scientific literature. On one side smoking may increase the risk of adverse outcomes in clinically overt COVID-19 requiring hospital admission. Several cross-sectional studies (case series) indicated a higher risk of negative disease progression among smokers compared to non-smokers in cases hospitalized with severe symptoms of the disease. On the other side, studies also suggest also that smoking is associated with a decreased risk of hospital admission with a diagnosis of COVID-19, or a decreased risk of occurrence of the disease in the community. These studies have noted 4 to 5 times lower proportions of smokers among patients hospitalized for COVID-19 compared with the underlying source population. A metanalysis of hospital case series confirmed this gap.
Given the public health importance of tobacco use as a risk factor for morbidity and mortality, it is urgent to provide both the scientific and the broad lay community with sound information from large population studies, something that the World Health Organization has also recommended.
Aim The present study aims to elucidate the potential causal association between tobacco use (smoking and snus) and COVID-19 using a population-based cohort study.
Methods In Sweden, the public dental clinics collect information at each visit on lifestyle and co-morbidities with relevance for oral health (health declaration), with a uniform instrument in use from October 2015. Smoking and snus use are ascertained as past use, current use and categories of intensity of current use. During February 2020 the usual routine activity of the clinics was disrupted by the pandemic, and the so-called oral health check-up was discontinued. About 450 000 adult clients of the public dentistry in Stockholm Region were identified in the period October 2015 to January 2020. Among these about 120000 were assessed within 7 months from the onset of the pandemic, therefore represent recent experiences. The investigators expect about 9% to be smokers and about 11% to be snus users. With the help of the national personal numbers assigned to every resident in Sweden at birth or at immigration, the investigators will link the reports of smoking among these clients with diagnoses of COVID-19 and other comorbidities registered in the regional database of inpatient and outpatient health care. The information in the dental clinic registers will be linked to the total population of the region of Stockholm, in order to extract socio-demographic information.
Statistical analysis plan The investigators will examine the role of tobacco use on the risk of the following events: any diagnosis of COVID-19, hospitalization, receiving intensive care, and death because of COVID-19 using generalized linear models, with and without possible confounders (age, gender, country of birth, type of employment, education and cohabitation), and within subgroups to identify potential effect modification (age group, gender [in analyses of snus use], assumed infection risk associated to occupation, pandemic period, and strategies of virologic testing, very restricted in the first 3 months, available on individual request thereafter).
Study design
- Observational model
- Cohort
- Time perspective
- Retrospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Cohort of adult client of public dental clinics in Region Stockholm | – | Behavioral: Tobacco useTobacco use (cigarette smoking and/or snus use) will be considered as exposure. Information on tobacco use will be extracted by public dental clinic records in Stockholm Region (October 2015-January 2020). Any diagnosis of COVID-19, hospitalization, receiving intensive care, and death because of COVID-19 will be examined as outcomes. Diagnoses of COVID-19 will be obtained through record linkage with health care registers of inpatient and outpatient care (February 2020-August 2021). |
Who may qualify
- Ages
- 23 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult clients of the public dental clinics in Stockholm Region (Sweden) in the period between October 2015 and January 2020.
Key inclusion criteria (3 listed)
- Being a client of the public dental clinics in the region of Stockholm (Sweden) between October 2015 and January 2020
- Being age 23 years or older
- Having tobacco use habits recorded in at least one visit
Key exclusion criteria (2 listed)
- Not having a Swedish personal identity number
- Resident in assisted elderly dwelling
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Tobacco use | Behavioural | Cohort of adult client of public dental clinics in Region Stockholm |
Primary outcome
Diagnosis of COVID-19
Time frame: 18 months from the index case of the pandemic in Sweden
Incident diagnoses of COVID-19, whether symptomatic or not, corresponding to a positive virologic test (PCR)
Hospital admission for COVID-19
Time frame: 18 months from the index case of the pandemic in Sweden
Rates of hospital admission due to COVID-19 reported in the hospital register
Intensive unit care because of a diagnosis of COVID-19
Time frame: 18 months from the index case of the pandemic in Sweden
Rates of admission to Intensive care units (IU) with a diagnosis of COVID-19 reported in the hospital register
Death for COVID-19
Time frame: 18 months from the index case of the pandemic in Sweden
COVID-19 death rates where COVID-19 is mentioned as cause of death reported in the death register
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Mar 2024.
- Background: PubMed 32109013Guan WJ, Ni ZY, Hu Y, Liang WH, Ou CQ, He JX, Liu L, Shan H, Lei CL, Hui DSC, Du B, Li LJ, Zeng G, Yuen KY, Chen RC, Tang CL, Wang T, Chen PY, Xiang J, Li SY, Wang JL, Liang ZJ, Peng YX, Wei L, Liu Y, Hu YH, Peng P, Wang JM, Liu JY, Chen Z, Li G, Zheng ZJ, Qiu SQ, Luo J, Ye CJ, Zhu SY, Zhong NS; China Medical Treatment Expert Group for Covid-19. Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med. 2020 Apr 30;382(18):1708-1720. doi: 10.1056/NEJMoa2002032. Epub 2020 Feb 28.
- Background: PubMed 32171076Zhou F, Yu T, Du R, Fan G, Liu Y, Liu Z, Xiang J, Wang Y, Song B, Gu X, Guan L, Wei Y, Li H, Wu X, Xu J, Tu S, Zhang Y, Chen H, Cao B. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. Lancet. 2020 Mar 28;395(10229):1054-1062. doi: 10.1016/S0140-6736(20)30566-3. Epub 2020 Mar 11.
- Background: PubMed 32077115Zhang JJ, Dong X, Cao YY, Yuan YD, Yang YB, Yan YQ, Akdis CA, Gao YD. Clinical characteristics of 140 patients infected with SARS-CoV-2 in Wuhan, China. Allergy. 2020 Jul;75(7):1730-1741. doi: 10.1111/all.14238. Epub 2020 Feb 27.
- Background: PubMed 32519944Dreher M, Kersten A, Bickenbach J, Balfanz P, Hartmann B, Cornelissen C, Daher A, Stohr R, Kleines M, Lemmen SW, Brokmann JC, Muller T, Muller-Wieland D, Marx G, Marx N. The Characteristics of 50 Hospitalized COVID-19 Patients With and Without ARDS. Dtsch Arztebl Int. 2020 Apr 17;117(16):271-278. doi: 10.3238/arztebl.2020.0271.
- Background: PubMed 32350106Rossato M, Russo L, Mazzocut S, Di Vincenzo A, Fioretto P, Vettor R. Current smoking is not associated with COVID-19. Eur Respir J. 2020 Jun 4;55(6):2001290. doi: 10.1183/13993003.01290-2020. Print 2020 Jun.
- Background: PubMed 32385628Farsalinos K, Barbouni A, Niaura R. Systematic review of the prevalence of current smoking among hospitalized COVID-19 patients in China: could nicotine be a therapeutic option? Intern Emerg Med. 2020 Aug;15(5):845-852. doi: 10.1007/s11739-020-02355-7. Epub 2020 May 9.
- Related InfoLink provided by the sponsor.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Maria Rosaria Galanti, PhD principal investigator
Karolinska Institutet
Questions about this trial
What is this clinical trial studying?
An observational study of Covid19, run by Karolinska Institutet.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 6 Mar 2024. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Diagnosis of COVID-19 (time frame: 18 months from the index case of the pandemic in Sweden). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04896918, which also lists 6 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Mar 2024.