Analysis of matched case-control studies

Neil Pearce, Neil Pearce

Abstract

There are two common misconceptions about case-control studies: that matching in itself eliminates (controls) confounding by the matching factors, and that if matching has been performed, then a “matched analysis” is required. However, matching in a case-control study does not control for confounding by the matching factors; in fact it can introduce confounding by the matching factors even when it did not exist in the source population. Thus, a matched design may require controlling for the matching factors in the analysis. However, it is not the case that a matched design requires a matched analysis. Provided that there are no problems of sparse data, control for the matching factors can be obtained, with no loss of validity and a possible increase in precision, using a “standard” (unconditional) analysis, and a “matched” (conditional) analysis may not be required or appropriate.

Conflict of interest statement

Competing interests: I have read and understood the BMJ policy on declaration of interests and declare the following: none.

Provenance and peer review: Not commissioned; externally peer reviewed.

References

    1. Rothman KJ, Greenland S, Lash TL, eds Design strategies to improve study accuracy.Modern epidemiology. 3rd ed Lippincott Williams & Wilkins, 2008.
    1. Rothman KJ. Epidemiology: an introduction.Oxford University Press, 2012.
    1. Rothman KJ, Greenland S, Lash TL, eds. Modern epidemiology. 3rd ed Lippincott Williams & Wilkins, 2008.
    1. Breslow NE, Day NE. Statistical methods in cancer research. Vol I: the analysis of case-control studies.IARC, 1980.
    1. Kleinbaum DG, Kupper LL, Morgenstern H. Epidemiologic research: principles and quantitative methods.Lifetime Learning Publications, 1982.
    1. Dos Santos Silva I. Cancer epidemiology: principles and methods.IARC, 1999.
    1. Keogh RH, Cox DR. Case-control studies.Cambridge University Press, 201410.1017/CBO9781139094757. .
    1. Lilienfeld DE, Stolley PD. Foundations of epidemiology. 3rd ed Oxford University Press, 1994.
    1. MacMahon B, Trichopolous D. Epidemiology: principles and methods. 2nd ed Little Brown, 1996.
    1. Mantel N, Haenszel W. Statistical aspects of the analysis of data from retrospective studies of disease. J Natl Cancer Inst 1959;22:719-48..
    1. Robins J, Greenland S, Breslow NE. A general estimator for the variance of the Mantel-Haenszel odds ratio. Am J Epidemiol 1986;124:719-23..
    1. Pike MC, Hill AP, Smith PG. Bias and efficiency in logistic analyses of stratified case-control studies. Int J Epidemiol 1980;9:89-95. 10.1093/ije/9.1.89. .
    1. Brookmeyer R, Liang KY, Linet M. Matched case-control designs and overmatched analyses. Am J Epidemiol 1986;124:693-701..
    1. Greenland S. Applications of stratified analysis methods. In: Rothman KJ, Greenland S, Lash TL, eds. Modern epidemiology. 3rd ed Lippincott Williams & Wilkins, 2008.
    1. Vandenbroucke JP, Koster T, Briët E, Reitsma PH, Bertina RM, Rosendaal FR. Increased risk of venous thrombosis in oral-contraceptive users who are carriers of factor V Leiden mutation. Lancet 1994;344:1453-7. 10.1016/S0140-6736(94)90286-0. .
    1. Cardis E, Richardson L, Deltour I, et al. The INTERPHONE study: design, epidemiological methods, and description of the study population. Eur J Epidemiol 2007;22:647-64. 10.1007/s10654-007-9152-z. .
    1. Mansournia MA, Hernán MA, Greenland S. Matched designs and causal diagrams. Int J Epidemiol 2013;42:860-9. 10.1093/ije/dyt083. .
    1. Hernán MA, Hernández-Díaz S, Robins JM. A structural approach to selection bias. Epidemiology 2004;15:615-25. 10.1097/01.ede.0000135174.63482.43. .

Source: PubMed

Sponsoren und Mitarbeiter

Krankheiten

Drogeninterventionen

3
Abonnieren