Clinical experience with aminoglycosides in dialysis-dependent patients: risk factors for mortality and reassessment of current dosing practices.

BACKGROUND

A resurgence of aminoglycoside use has followed the recent increase of multidrug-resistant gram-negative pathogens and is often needed even in the treatment of dialysis-dependent patients; however, studies evaluating the treatment of gram-negative infections with aminoglycosides, including the optimal dose, in the setting of dialysis are limited.

OBJECTIVE

To evaluate the current patterns of aminoglycoside use, including microbiologic and clinical indications, and identify risk factors associated with mortality in dialysis-dependent patients receiving aminoglycosides.

METHODS

Utilization, clinical, and microbiologic data were collected retrospectively over a 2-year period (July 2008-June 2010) for adults with a diagnosis of renal failure requiring dialysis and aminoglycoside therapy. Binary logistic and multivariate regression analyses were performed to identify risk factors for all-cause 30-day mortality.

RESULTS

Ninety-five consecutive aminoglycoside courses in 88 patients met inclusion criteria for evaluation. A wide variety of clinical and microbiologic indications were documented. The average duration of aminoglycoside therapy was 5.2 days (range 1-42), the average duration of antimicrobial therapy was 13.5 days (1-60), and the all-cause 30-day mortality rate was 36.5%. Factors associated with all-cause 30-day mortality were gram-negative rod (GNR) bacteremia (OR 28.6; p = 0.035), advanced age (OR 8.5; p = 0.030), recent admission (OR 33.4; p = 0.038), and inadequate empiric therapy (OR 14.9; p = 0.024). Intravenous catheter removal was protective of all-cause 30-day mortality (OR 0.01; p = 0.005). A first pre-dialysis plasma concentration relative to the minimum inhibitory concentration (Cp:MIC) <6 mg/L (gentamicin/tobramycin) was associated with an increased risk of mortality (p = 0.026) upon subgroup analysis of dialysis-dependent patients with GNR bloodstream infections.

CONCLUSIONS

Outcomes among dialysis-dependent patients who received aminoglycosides were below expectations. Various risk factors for mortality were identified, including retention of the catheter, inadequate empiric therapy, and a Cp:MIC <6 mg/L. Improved approaches to dosing of aminoglycosides in dialysis-dependent patients, including more aggressive dosing practices, should be urgently explored in attempts to maximize favorable patient outcomes.