Introduction to Confounding

  • Bryan Kestenbaum

Learning Objectives

  1. 1.

    Confounding is an important limitation of observational studies.

  2. 2.

    Confounding alters the interpretation of study results, obscuring whether the exposure is a cause of the outcome.

  3. 3.
    A confounder is classically defined as a factor that is:
    1. a.

      associated with the exposure,

    2. b.

      associated with the outcome, and

    3. c.

      not in the causal pathway of association.

  4. 4.

    Study data are used to judge whether a potential confounder is associated with the exposure and the outcome.

  5. 5.

    Biological and clinical knowledge are used to judge whether a potential confounder is in the causal pathway of association.

  6. 6.

    Confounding-by-indication occurs when the specific indication for a medication confounds the association between the use of that medication and the study outcome.



Potential Confounder Loop Diuretic Causal Pathway Mast Cell Degranulation Acute Bronchitis 
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  1. 38.
    Hu FB, Stampfer MJ, Manson JE, et al. Dietary fat intake and the risk of coronary heart disease in women. N Engl J Med. Nov 20 1997;337(21):1491–1499.CrossRefPubMedGoogle Scholar
  2. 39.
    Psaty BM, Koepsell TD, Lin D, et al. Assessment and control for confounding by indication in observational studies. J Am Geriatr Soc. Jun 1999;47(6):749–754.PubMedGoogle Scholar
  3. 40.
    Mehta RL, Pascual MT, Soroko S, Chertow GM. Diuretics, mortality, and nonrecovery of renal function in acute renal failure. JAMA. Nov 27 2002;288(20):2547–2553.CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.University of WashingtonSeattleUSA

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