Indirect comparison in evaluating relative efficacy illustrated by antimicrobial prophylaxis in colorectal surgery

This paper aims to explore the potential usefulness and limitations of indi rect comparisons in evaluating the relative efficacy of interventions. From a systematic review of antimicrobial prophylaxis in colorectal surgery, we identified 11 sets of randomized trials that can be used to compare antibi otics both directly and indirectly. The discrepancy between the direct and the indirect comparison is defined as the absolute value of difference in l og odds ratio. The adjusted indirect comparison has the advantages that the prognostic factors of participants in different trials can be partially ta ken into account and more uncertainty be incorporated into its result by pr oviding a wider confidence interval. However, considerable discrepancies ex ist between the direct and the adjusted indirect comparisons. When there is no direct comparison, the adjusted indirect method may be used to obtain s ome evidence about the relative efficacy of competing interventions, althou gh such indirect results should be interpreted with great caution. Further empirical and methodologic research is needed to explore the validity and g eneralizability of the adjusted indirect comparison fur evaluating differen t interventions. (C) Elsevier Science Inc. 2000.