Risk factors for nephrotoxicity onset associated with polymyxin B therapy.

OBJECTIVES

Polymyxin B is an active agent against many MDR Gram-negative bacteria, but nephrotoxicity is a major hindrance to its widespread use. To guide its optimal use, we determined the risk factors for nephrotoxicity onset associated with polymyxin B.

METHODS

In a multicentre, retrospective, cohort study, we evaluated adult patients with normal renal function who received ≥72 h of polymyxin B therapy. Pertinent information was retrieved from medical records; patients were followed for up to 30 days after therapy was started. The primary endpoint of this study was the onset of nephrotoxicity. A Cox proportional hazards model was used for analysis.

RESULTS

A total of 192 patients (52.1% male, 67.7% Caucasian) were evaluated. The mean ± SD age, actual body weight (ABW) and daily dose by ABW were 68.3 ± 17.2 years, 71.5 ± 20.4 kg and 1.5 ± 0.5 mg/kg, respectively. The median duration of therapy was 9.5 days. The overall prevalence rate of nephrotoxicity was 45.8% and the median onset of nephrotoxicity was 9 days. Independent risk factors for the onset of nephrotoxicity included daily dose by ABW (HR = 1.73; P = 0.022), concurrent use of vancomycin (HR = 1.89; P = 0.005) and contrast media (HR = 1.79; P = 0.009). Nephrotoxicity was seen earlier in the high-risk group (P = 0.003).

CONCLUSIONS

Risk factors for nephrotoxicity onset associated with polymyxin B were identified. In conjunction with susceptibility and other pharmacokinetic/pharmacodynamic data, our results can be used to optimize treatment for MDR Gram-negative infections.