Methodological principles of case-control studies that analyzed risk factors for antibiotic resistance: A systematic review

Case-control studies that analyze the risk factors for antibiotic-resistant organisms have varied epidemiological methodologies, which may lead to bia sed estimates of antibiotic risk factors. A systematic review of case-contr ol studies that analyzed risk factors for antibiotic-resistant organisms ad dressed 3 methodological principles: method of control group selection, adj ustment for time at risk, and adjustment for comorbid illness. A total of 4 06 abstracts were reviewed. Thirty-seven studies met the inclusion and excl usion criteria and were reviewed and evaluated for the 3 methodological pri nciples. Thirteen (35%) of 37 studies chose the preferred control group. El even adjusted for time at risk. Twenty-seven adjusted for comorbid illness. Future studies need to consider more closely the optimization of control g roup selection, adjusting for confounding caused by time at risk, and adjus ting for confounding caused by comorbid illness.