Incidence of Acute Kidney Injury in Intermittent Versus Continuous Infusion of Polymyxin B in Hospitalized Patients

Background: Studies evaluating the risk of developing acute kidney injury (AKI) with different dosing strategies of polymyxin B are limited. Objectives: To compare the incidence of AKI in patients treated with intermittent versus continuous polymyxin B therapy. Secondary objectives included time to onset of AKI, hospital length of stay (LOS), and all-cause hospital mortality. Variables associated with an increased risk of AKI were evaluated. Methods: A retrospective record review was conducted at a single center in Puerto Rico. Adult patients (≥18 years old) treated with polymyxin B (first course) for at least 48 hours from 2013-2015 were evaluated. Patients with a creatinine clearance <10 mL/min and/or on renal replacement were excluded. Results: A total of 69 patients were included: 42 in the continuous infusion and 27 in the intermittent dosing group. Incidence of AKI was not significantly different between the groups (intermittent 41% vs continuous 31%, P = 0.4). No difference was found in the onset of nephrotoxicity, hospital LOS, or all-cause hospital mortality. Variables associated with increased risk of AKI were baseline serum creatinine, age, and intensive care unit admission. Patients with a body mass index (BMI) >25 kg/m ² on polymyxin B via continuous infusion had a significantly higher cumulative incidence of AKI ( P = 0.016). Conclusion and Relevance: No difference in the risk of polymyxin B nephrotoxicity was found between intermittent and continuous infusion administration. Administration of polymyxin B via a continuous infusion may result in a higher risk of AKI in patients with a BMI >25 kg/m ² .