Assessment and Indirect Adjustment for Confounding by Smoking in Cohort Studies Using Relative Hazards Models
Open accessAbstract
Workers' smoking histories are not measured in many occupational cohort studies. Here we discuss the use of negative control outcomes to detect and adjust for confounding in analyses that lack information on smoking. We clarify the assumptions necessary to detect confounding by smoking and the additional assumptions necessary to indirectly adjust for such bias. We illustrate these methods using data from 2 studies of radiation and lung cancer: the Colorado Plateau cohort study (1950-2005) of underground uranium miners (in which smoking was measured) and a French cohort study (1950-2004) of nuclear industry workers (in which smoking was unmeasured). A cause-specific relative hazards model is proposed for estimation of indirectly adjusted associations. Among the miners, the proposed method suggests no confounding by smoking of the association between radon and lung cancer--a conclusion supported by adjustment for measured smoking. Among the nuclear workers, the proposed method suggests substantial confounding by smoking of the association between radiation and lung cancer. Indirect adjustment for confounding by smoking resulted in an 18% decrease in the adjusted estimated hazard ratio, yet this cannot be verified because smoking was unmeasured. Assumptions underlying this method are described, and a cause-specific proportional hazards model that allows easy implementation using standard software is presented.
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In that situation, the difference of the negative control results from the null can be used as an indicator of the extent of bias in the original study.
“In that situation, the difference of the negative control results from the null can be used as an indicator of the extent of bias in the original study.41,42”
From Triangulation in aetiological epidemiology (2017) · cites this paper as [41]
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- Authors
- Richardson, D. B., Laurier, D., Schubauer-Berigan, M. K., Tchetgen, E. T., & Cole, S. R.
- Affiliations
- University of North Carolina at Chapel Hill (US)
- Corresponding author
- Richardson, D. B.
- Venue
- American Journal of Epidemiology
- Publisher
- Oxford University Press (OUP)
- Published
- 2014-09-21
- Volume
- 180
- Issue
- 9
- Pages
- 933-940
- ISSN
- 0002-9262 (ISSN-L)
- 1476-6256
- PMC
- PMC4375397
- OpenAlex
- W2122091203
- Cited by
- 51
- References
- 27
- Citations by year
- 2026: 1 · 2025: 7 · 2024: 4 · 2023: 6 · 2022: 5 · 2021: 5 · 2020: 5 · 2019: 3 · 2018: 1 · 2017: 7 · 2016: 2 · 2015: 5
- FWCI
- 4.93
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- American Journal of Epidemiology (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Carolina Digital Repository (University of North Carolina at Chapel Hill) (submittedVersion)
- HAL (submittedVersion)
- UNC Libraries
- Funders
- Areva
- Harvard University
- European Commission
- Electricité de France
- University of North Carolina at Chapel Hill
- Fifth Framework Programme
- National Institute of Allergy and Infectious Diseases (R01AI104459)
- National Institute of Environmental Health Sciences (R01ES020337)
- National Institute for Occupational Safety and Health
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
- Health Sciences › Medicine › Oncology › Global Cancer Incidence and Screening
- Keywords
- smoking confounding, indirect adjustment, negative control outcomes, smoking history, occupational cohort studies, radon exposure, lung cancer, uranium miners, nuclear workers, radiation exposure, unmeasured confounding
- MeSH terms
- Epidemiologic Methods, Humans, Lung Neoplasms, Mining, Neoplasms, Radiation-Induced, Retrospective Studies, Smoking, Social Class, Uranium, Cohort Studies, Confounding Factors, Epidemiologic, Proportional Hazards Models, Occupational Exposure
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