Colistin versus polymyxin B for the treatment of patients with multidrug-resistant Gram-negative infections: a systematic review and meta-analysis.

Colistin and polymyxin B (PMB) have different pharmacokinetic profiles and minor differences in antimicrobial activities that may result in discrepancies in mortality and nephrotoxicity. A systematic review and meta-analysis was conducted. PubMed, Scopus and Cochrane Library databases were searched. There was no significant difference in unadjusted mortality between patients treated with colistin and PMB [risk ratio (RR) = 0.71, 95% confidence interval (CI) 0.45-1.13]. Adjusted data were not available. Unadjusted nephrotoxicity was more common in patients treated with colistin than PMB (RR = 1.55, 95% CI 1.36-1.78). According to the RIFLE (Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease) criteria, there was no difference regarding risk, injury or failure between colistin and PMB. Although episodes of loss of renal function were few in general, they developed primarily in colistin-treated patients (RR = 8.55, 95% CI 1.48-49.49). Colistin was associated with more episodes of nephrotoxicity that also occurred sooner in the analysis of adjusted data (hazard ratio = 2.16, 95% CI 1.43-3.27). Colistin administration was an independent risk factor for nephrotoxicity in two studies. Future studies should evaluate in depth the factors associated with mortality and nephrotoxicity in patients treated with polymyxins and the impact of polymyxin-associated nephrotoxicity on mortality.