How to control confounding effects by statistical analysis

Mohamad Amin Pourhoseingholi, Ahmad Reza Baghestani, Mohsen Vahedi, Mohamad Amin Pourhoseingholi, Ahmad Reza Baghestani, Mohsen Vahedi

Abstract

A Confounder is a variable whose presence affects the variables being studied so that the results do not reflect the actual relationship. There are various ways to exclude or control confounding variables including Randomization, Restriction and Matching. But all these methods are applicable at the time of study design. When experimental designs are premature, impractical, or impossible, researchers must rely on statistical methods to adjust for potentially confounding effects. These Statistical models (especially regression models) are flexible to eliminate the effects of confounders.

Keywords: Adjustment; Confounders; Statistical models.

References

    1. Elwood JM, editor. Causal Relationships in Medicine. Oxford: Oxford University Press; 1988. p. 332.
    1. Agresti A, editor. An introduction to categorical data analysis. New Jersey: Wiley; 2007. p. 51.
    1. Mayrent SL, editor. Epidemiology in Medicine. New York: Lippincott Williams & Wilkins; 1987.
    1. Christenfeld NJ, Sloan RP, Carroll D, Greenland S. Risk factors, confounding, and the illusion of statistical control. Psychosom Med. 2004;66:868–75.
    1. Maldonado G, Greenland S. Simulation study of cofounder-selection strategies. Compares a number of data based strategies for selecting variables to include in regression models when the aim is to control confounding. Am J Epidemiol. 1993;138:923–36.
    1. Wunsch G. Confounding and control. Demographic Research. 2007;16:97–120.
    1. Greenland S. Quantifying biases in causal models: classical confounding vs. collider-stratification bias. Epidemiology. 2003;14:300–6.
    1. Cole SR, Hernan MA. Fallibility is estimating direct effects. Int J Epidemiol. 2002;31:163–65.
    1. Greenland S, Brumback BA. An overview of relations among causal modelling methods. Int J Epidemiol. 2002;31:1030–37.
    1. Blair A, Stewart P, Lubin JH, Forastiere F. Methodological issues regarding confounding and exposure misclassification in epidemiological studies of occupational exposures. Am J Ind Med. 2007;50:199–207.
    1. McNamee R. Confounding and confounders. Contrasts competing definitions of a confounder, including those based on data and those based on notions of comparability. Occup Environ Med. 2003;60:227–34.
    1. Greenland S, Morgenstern H. Confounding in health research. Annu Rev Public Health. 2001;22:189–212.
    1. Greenland S, Pearl J, Robins JM. The problem of identifying confounders of an exposure-disease relationship is addressed through causal diagrams. Causal diagrams for epidemiological research. Epidemiology. 1999;10:37–47.
    1. McNamee R. Regression modelling and other methods to control confounding. Occup Environ Med. 2005;62:500–506.

Source: PubMed

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