Risk factors for acute kidney injury in patients treated with polymyxin B at a Tertiary Care Medical Center.

INTRODUCTION: Polimyxins were originally abandoned due to high rates of nephrotoxicity. However they have been recently reintroduced due to activity against carbapenem-resistant Gram-negative organisms. Recent literature suggests a lower rate of nephrotoxicity than historically reported.

OBJECTIVE: To determine the rate of polymixins-associated nephrotoxicity as defined by the RIFLE criteria.

METHODS: A retrospective cohort of all adult patients who received polymixin B at a terciary hospital from December 2010 to March 2011was performed.

RESULTS: 61 patients (43%) fulfilled the RIFLE criteria for renal injury and 28 patients (13.7%) needed dialysis. Independent predictors for nephrotoxicity were hypotension (OR, 2.79; CI 1.14-5.8; p = 0.006) and concomitant use of vancomycin (OR, 2.86; CI, 1.27-6.4; p = 0.011).

CONCLUSIONS: In this retrospective cohort, nephrotoxicity (as defined by RIFLE criteria) occurred among 43% of treated patients. The concomitant use of vancomycin and hypotension were independent risk factors of nephropathy. Further studies are needed, particularly with polymyxin B, to clarify if the characteristics of this drug and colistin are overlapping.