Renal safety of short-term empiric gentamicin therapy in aged patients

Objective: To determine the incidence of acute kidney injury (AKI) in aged patients receiving empiric gentamicin therapy. Methods: Patients aged ≥65 years receiving gentamicin upon admission between 2013 and 2015 at two Australian hospitals were retrospectively studied. AKI was defined as a rise in creatinine by ≥50% and/or ≥26.5 μmol/L. Results: Most patients (95%) received a single dose of gentamicin. The incidence of AKI was 15% (36/242 patients). A composite outcome of persistent kidney injury, requirement for renal replacement therapy or inpatient death in a patient with AKI occurred in 10 (4%) patients. Patients who developed AKI were older (median 80.5 vs 78 years, P = 0.03), had higher Charlson Co-morbidity Index (median 7 vs 5, P = 0.0004) and had more advanced chronic kidney disease at baseline (Stages IV and V) (OR 4.38, 95% confidence interval 1.45-13.2, P = 0.01). Conclusion: Empiric gentamicin use in patients with advancing age is associated with low rates of predominantly transient renal impairment.