Aminoglycoside-associated nephrotoxicity in the elderly

Objective: To determine whether there was an increased incidence of nephrotoxicity in elderly patients (greater than or equal to65 y) prescribed single-dose (SD) versus multiple-dose (MD) aminoglycosides and whether aminoglycoside-induced nephrotoxicity was associated with length of therapy and other risk factors. Methods: A prospective, observational audit at a university teaching hospital was conducted. Physician prescribing was used to stratify subjects according to dosing regimen: MD (n=60) or SD (n=26). Nephrotoxicity was defined as an increase in the serum creatinine level of 0.5 mg/dL sustained over 2 days. Results: Eighty-six patients were included; 9.3% developed nephrotoxicity, of whom 62.5% received SD therapy. The incidence of nephrotoxicity did not differ between regimens (p=0.051). There was an increased length of therapy in those who developed nephrotoxicity (mean+/-SD 6.1+/-6.2 vs. 3.7+/-2.8 d; p=0.044). Additionally, patients who developed nephrotoxicity had an increased length of hospitalization (20.3+/-16.1 vs. 8.4+/-5.4 d; p<0.001). Nephrotoxicity correlated with a diagnosis of diabetes mellitus (OR 15.1; 95% CI 1.11 to 205), concomitant angiotensin-converting enzyme (ACE) inhibitor therapy (OR 28.0; 95% CI 2.15 to 365), and SD therapy (OR 20.7; 95% CI 1.45 to 297). Conclusions: Our overall incidence of nephrotoxicity is consistent with that reported in the literature. A diagnosis of diabetes mellitus, concomitant use of ACE inhibitors, and SD regimens were risk factors for the development of nephrotoxicity. An adequately powered, randomized trial is needed to assess whether a difference in the incidence of nephrotoxicity exists between SD and MD therapy in the elderly.