Background: The incidence of gentamicin-associated acute kidney injury (AKI) as defined by the RIFLE criteria is unknown.

Aim and design: We performed a retrospective observational study to examine this and the predictive value of RIFLE stage on patient outcome in this setting.

Methods: We included all patients who were treated with gentamicin at our centre over a 1-month period. Data on 228 patients across all specialities were collected by manual searching of hospital notes and electronic pathology reporting systems. Information collected included baseline and peak serum creatinine results, gentamicin dose and serum levels, the presence of additional renal insults and the Stoke co-morbidity index.

Results: AKI occurred in 51 (24.4%) patients; 37 (17.7%) ‘Risk’, 9 (4.3%) ‘Injury’, 5 (2.4%) ‘Failure’. Independent predictors of gentamicin associated AKI were number of gentamicin levels >2 mg/l (OR 1.845, 95% CI 1.22 to 2.79) and higher baseline serum creatinine (OR 1.014, 95% CI 1.001–1.028). There was a greatly increased risk of in-hospital mortality in the AKI group as compared to those without AKI (45.1% vs. 19.1%, OR 3.48, 95% CI 1.8–6.9, P = 0.0004). Risk of in hospital mortality increased with each RIFLE stage (P < 0.0001).

Conclusions: This study shows that gentamicin-associated AKI remains a common and potentially serious clinical problem. There is a strong correlation between RIFLE class and in-hospital mortality.