Analysis of matched case-control studies

BMJ. 2016 Feb 25:352:i969. doi: 10.1136/bmj.i969.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Case-Control Studies*
  • Confounding Factors, Epidemiologic
  • Control Groups
  • Data Interpretation, Statistical