Expired CME Article

Understanding and Identifying Bias and Confounding in the Medical Literature

Authors: Joe L. Hsu, MD, MPH, Dipanjan Banerjee, MD, Ware G. Kuschner, MD

Abstract

Bias and confounding are types of error that may be encountered in the collection, analysis, or interpretation of research data. Bias and confounding may result in erroneous research conclusions with adverse consequences for patients and health care providers. In this article, we provide clinician-friendly descriptions and examples of bias (including surveillance, information, selection, lead, length, and publication) and confounding. The purpose of the article is to help clinicians to recognize two important sources of error in research and in turn to help clinicians to assess the validity and generalizability of a research report.

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References

1. Greenberg RS, Daniels SR, Flanders WD, et al. Medical Epidemiology. Stamford, CT, Appleton and Lange, 1996, ed 2.
 
2. Greenland S, Morgenstern H. Confounding in health care research. Annu Rev Public Health 2001;22:189–212.
 
3. Rothman KJ. Modern Epidemiology. Boston, MA, Toronto, Canada, Little, Brown and Company, 1986.
 
4. Jajosky P. Sarcoidosis diagnoses among U.S. military personnel: trends and ship assignment associations. Am J Prev Med 1998;14:176–183.
 
5. Centers for Disease Control and Prevention (CDC). Sarcoidosis among U.S. navy enlisted men, 1965–1993. MMWR Morb Mortal Wkly Rep 1997;46:539–543.
 
6. Thun MJ, Sinks T. Understanding cancer clusters. CA Cancer J Clin 2004;54:273–280.
 
7. Rothman KJ. Clustering of disease [editorial]. Am J Public Health 1987;77:13–15.
 
8. International Early Lung Cancer Action Program Investigators; Henschke CI, Yankelevitz DF, Libby DM, et al. Survival of patients with stage I lung cancer detected on CT screening. N Engl J Med 2006;355:1763–1771.
 
9. Bach PB, Jett JR, Pastorino U, et al. Computed tomography screening and lung cancer outcomes. JAMA 2007;297:953–961.
 
10. Wilde J. A 10 year follow-up of semi-annual screening for early detection of lung cancer in the Erfurt County, GDR. Eur Respir J 1989;2:656–662.
 
11. Mazzone P, Obuchowski N, Mekhail T, et al. Lung cancer screening: is it time for a change in policy? Cleve Clin J Med 2007;74:441–448.
 
12. Grimes DA, Schulz KF. Bias and causal associations in observational research. Lancet 2002;359:248–252.
 
13. Sica GT. Bias in research studies. Radiology 2006;238:780–789.
 
14. Arrighi HM, Hertz-Picciotto I. The evolving concept of the healthy worker survivor effect. Epidemiology 1994;5:189–196.
 
15. Gluud LL. Bias in clinical intervention research. Am J Epidemiol 2006;163:493–501.
 
16. Sterne JAC, Egger M. Funnel plots for detecting bias in meta-analysis: guidelines on the choice of axis. J Clin Epidemiol 2004;54:1046–1055.
 
17. Naylor CD. Meta-analysis and the meta-epidemiology of clinical research [editorial]. BMJ 1997;315:617–619.
 
18. Bagshaw SM, Ghali WA. Acetylcysteine for the prevention of contrast-induced nephropathy after interventional angiography: a systematic review and meta-analysis. BMC Med 2004;2:38.
 
19. ISIS-4: a randomized factorial trial assessing early oral captopril, oral mononitrate, and intravenous magnesium in 58,050 patients with suspected acute myocardial infarction. ISIS-4 (Fourth International Study of Infarct Survival) Collaborative Group. Lancet 1995;345:669–685.
 
20. Weinstein JN, Tosteson TD, Lurie JD, et al. Surgical versus nonoperative treatment for lumbar disc herniation the spine patient outcomes research trial (SPORT): a randomized clinical trial. JAMA 2006;296:2441–2450.