Matching criteria in case-control studies in postoperative infections

Abstract number: 1733_1423

Falagas M.E., Mourtzoukou E.G., Ntziora F., Peppas G., Rafailidis P.I.

Background: Matching is commonly used in case-control studies to control for the effect of major confounding factors. We sought to evaluate the available evidence from case-control studies regarding postoperative infections to identify how frequently matching was performed and with what specific variables.

Methods: We searched for relevant case-control studies archived by PubMed until August 2006. Only studies regarding postoperative infections were included in our review. We further evaluated studies that used individual matching between cases and controls.

Results: We identified and evaluated 42 relevant studies. Age was used as a matching criterion in 27 of these 42 (64.3%) case-control studies. The specific type of surgical procedure was the second most commonly used criterion, in 17 of 42 studies (40.5%). Gender was used in 14 of 42 studies (33.3%) as a matching criterion between case and control patients. The period at risk for development of surgical site and/or other postoperative infections, that is the time from surgery to the diagnosis of infection was used in 9 of 42 studies (21.4%), as was the date of operation, and the primary diagnosis that led the case and control patients to surgery. Same surgeon or surgical team was used in 7 studies (16.7%), while matching according to the National Nosocomial Infection Surveillance system risk score was performed in 5 studies (11.9%).

Discussion: The findings of our analysis suggest that various characteristics have been used for matching in case-control studies of postoperative infections. A more consistent use of matching with the specific type of surgical procedure may help in increasing the internal validity of a case-control study in this field of clinical research.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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