Comparison of the incidence of vancomycin-induced nephrotoxicity in hospitalized patients with and without concomitant piperacillin-tazobactam.

STUDY OBJECTIVES: To determine whether the addition of piperacillin-tazobactam leads to an increased incidence of nephrotoxicity in patients receiving vancomycin and to explore potential confounding factors that may increase the risk of vancomycin-induced nephrotoxicity. DESIGN: Single-center, retrospective cohort study. SETTING: Large, academic, tertiary-care hospital. PATIENTS: One hundred ninety-one adults hospitalized between July 1, 2009, and July 1, 2012, with normal baseline renal function who received a minimum of 48 hours of vancomycin for any indication were included in the analysis. Of these patients, 92 received a minimum of 48 hours of intravenous piperacillin-tazobactam concurrently with vancomycin, with piperacillin-tazobactam being initiated within 48 hours of the initiation of vancomycin (combination group); 99 received vancomycin without piperacillin-tazobactam (vancomycin group). MEASUREMENTS AND MAIN RESULTS: A univariate analysis was performed to assess the effect of the following risk factors on the incidence of nephrotoxicity within the first 7 days of vancomycin treatment: concomitant nephrotoxic agents, advanced age, steady-state vancomycin trough concentration of 15 μg/ml or greater, elevated Charlson Comorbidity Index, and a total daily vancomycin dose of 4 g or greater. A multivariate model was constructed to compare the incidence of the primary end point of nephrotoxicity, defined as a minimum 1.5-fold increase in serum creatinine concentration, between groups. Nephrotoxicity developed in 8 (8.1%) of 99 patients in the vancomycin group and in 15 (16.3%) of 92 patients in the combination group (1-sided χ(2) test, p=0.041). In the univariate analysis, only vancomycin trough concentration of 15 μg/ml or greater (odds ratio 3.67) was associated with an increased risk of developing nephrotoxicity. In the multivariate analysis, patients with piperacillin-tazobactam added to vancomycin exhibited an increased incidence of nephrotoxicity, with an odds ratio of 2.48 (1-sided χ(2) test, p=0.032). CONCLUSION: We observed an increased incidence of nephrotoxicity in vancomycin-treated patients who received concomitant piperacillin-tazobactam. A steady-state vancomycin trough concentration of 15 μg/ml or greater was also associated with an increased risk of the development of nephrotoxicity. These findings should be confirmed in larger, randomized studies.

Duke Scholars

Author Richard Howard Drew Medicine, Infectious Diseases