Methodological issues regarding confounding and exposure misclassification in epidemiological studies of occupational exposures

American Journal of Industrial Medicine - Tập 50 Số 3 - Trang 199-207 - 2007
Aaron Blair1, Patricia A. Stewart2, Jay H. Lubin2, Francesco Forastiere3
1Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, Maryland 20892, USA.
2Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, Maryland
3Department of Epidemiology, ASL Roma E, Via Santa Costanza 53, Roma, Italy

Tóm tắt

AbstractBackgroundConfounding and exposure misclassification are issues that concern epidemiologists because of their potential to bias results of studies and complicate interpretations. In occupational epidemiology both are routinely raised to argue that an observed result is either a false positive or a false negative finding. Although it is important to consider the potential for limitations of epidemiologic investigations, judgment regarding their importance should be based on their actual likelihood of occurrence.MethodsThis paper is based on our experience in epidemiologic analyses and a brief review of the literature regarding confounding and exposure misclassification.ResultsExamples of substantial confounding are rare in occupational epidemiology. In fact, even for studies of occupational exposures and lung cancer, tobacco‐adjusted relative risks rarely differ appreciably from the unadjusted estimates. This is surprising because it seems the perfect situation for confounding to occur. Yet, despite the lack of evidence that confounding is a common problem, nearly every epidemiologic paper includes a lengthy discussion on uncontrolled or residual confounding. On the other hand, exposure misclassification probably occurs in all studies. The only question is, how much? The direction and magnitude of nondifferential exposure misclassification (the type most likely to occur in cohort studies) on estimates of relative risks can be largely predicted given knowledge on the degree of misclassification, that is, relatively small amounts of misclassification can bias relative risks substantially towards the null. The literature, however, is full of discussions implying that misclassification of exposure is an explanation for a positive finding.ConclusionsThese comments are not to suggest that all potential limitations for epidemiologic studies should not be considered and evaluated. We do believe, however, that the likelihood of occurrence and the direction and magnitude of the effect should be more carefully and realistically considered when making judgments about study design or data interpretation. Am. J. Ind. Med. 50: 199–207, 2007. © 2006 Wiley‐Liss, Inc.

Từ khóa


Tài liệu tham khảo

10.1093/ije/22.Supplement_2.S83

10.1016/S1047-2797(00)90000-0

Axelson O, 1978, Aspects on confounding in occupational health epidemiology, Scand J Work Environ Health, 10, 325

Axelson O, 1985, Dealing with the exposure variable in occupational and environmental epidemiology, Scand J Soc Med, 18, 147, 10.1177/140349488501300404

10.1021/bk-1992-0542.ch014

10.1093/ije/26.3.635

Blair A, 1985, Comparison of crude and smoking‐adjusted standardized mortality rates, J Occup Med, 27, 881

Blair A, 1995, A philosophy for dealing with hypothesized uncontrolled confounding in epidemiological investigations, Med Lav, 86, 106

Blair A, 1998, Mortality of industrial workers exposed to acrylonitrile, Scand J Work Environ Health, 24, 25

10.1002/ajim.4700130103

Breslow NE, 1980, The analysis of case‐control studies, 338

10.1093/oxfordjournals.aje.a010218

10.1093/aje/145.8.680

10.1093/acprof:oso/9780195092424.001.0001

10.1093/oxfordjournals.aje.a112408

10.1093/oxfordjournals.aje.a115716

10.1093/annhyg/meg059

10.1002/ajim.4700130108

10.1093/ije/dyi060

Kriebel D, 2004, Quantitative evaluation of the effects of uncontrolled confounding by alcohol and tobacco in occupational cancer studies, Int J Epidemiol, 13, 1

10.1097/00004032-199104000-00002

Levin L, 1988, Occupation and lung cancer in Shanghai: A case‐control study, Brit J Ind Med, 45, 450

Levitt SD, 2005, Freakonomics: A rogue economist explores the hidden side of everything, 242

10.1093/oxfordjournals.aje.a010243

10.1093/annhyg/39.3.291

10.1136/oem.2004.015941

Rothman JK, 1998, Modern epidemiology

10.1093/oxfordjournals.aje.a115210

10.1097/00043764-198808000-00004

10.1002/ajim.4700130105

10.1093/carcin/9.7.1159

10.1093/jnci/91.9.779

10.1002/ajim.4700130104

10.5271/sjweh.509

10.1093/annhyg/meg060

10.1093/oxfordjournals.aje.a114049

10.1080/00039896.1982.10667586

Thông tin
Thông tin xuất bản

American Journal of Industrial Medicine

Tập 50 Số 3

199-207

Thông tin tác giả