Acute kidney injury following amikacin therapy: a retrospective cohort study

Aminoglycosides are historically considered nephrotoxic, though contemporary once-daily dosing and preferential amikacin use may reduce this risk. We evaluated the incidence and risk factors for acute kidney injury (AKI) among patients receiving amikacin.

A retrospective cohort study of adult inpatients treated with amikacin between July 2018 and June 2022. Exclusion criteria were treatment <3 or >10 days, baseline eGFR <30 mL/min/1.73 m2, or insufficient renal follow-up. AKI was defined by KDIGO criteria. Charts of patients meeting AKI criteria were reviewed to assess likely aetiology. Multivariate logistic regression identified independent predictors.

Of 974 courses, 608 met the inclusion criteria. Patients had a median age of 81.0 years, 52.5% were female and the median baseline eGFR was 67.1 mL/min/1.73 m2. AKI occurred in 48 patients (7.9%), with KDIGO stage 2-3 in 14 (2.3%). Aetiologies included prerenal azotaemia (21%), shock/sepsis (35%), urinary obstruction (17%), contrast exposure (2.1%) and other nephrotoxic medications (2.1%); in 11 patients (22.9% of patients with AKI and 1.8% of the entire cohort), no alternative cause was identified. Multivariate analysis showed independent predictors of AKI were older age, longer interval from admission to treatment and discontinuation due to an infectious indication. Baseline eGFR, daily dose and treatment duration were not associated with AKI.

In this contemporary cohort, we observed a relatively low incidence of AKI, often secondary to, or exacerbated by, other underlying causes. These findings suggest that once-daily amikacin may potentially carry a lower nephrotoxic risk than historically reported. Further studies are warranted to confirm safety in broader patient populations.