Persistent kidney dysfunction after acute kidney injury predicts short-term outpatient mortality

Background Acute kidney injury (AKI) during hospitalisation is frequent and associated with adverse outcomes. Aims To evaluate the association between renal function recovery after AKI and short-term post-discharge mortality. Methods This is a retrospective study of all AKI episodes codified in the electronic records of a single centre in 2013 and 2014. Epidemiological data and comorbidities at baseline and laboratory values at admission and discharge were collected. Persistent kidney dysfunction after AKI was defined as a last serum creatinine equal or above 1.2-fold over baseline level. Patients were followed for 30 days after discharge. Results Out of 1720 evaluated patients, 1541 (89%) were analysed. Of them, 869 (56%) recovered renal function. Independent predictors of renal function recovery after AKI were lower baseline estimated glomerular filtration rate (eGFR) (P < 0.001), higher admission eGFR (P < 0.001) and haemoglobin (P = 0.016), milder AKI (P = 0.037), absence of a history of heart failure (P < 0.001) and lower admission blood pressure (P < 0.001). After discharge, 46 (3%) patients died in the first 30 days. Persistent kidney dysfunction was associated (P = 0.01) with and independently predicted (odds ratio 2.6; 95% confidence interval 1.2-5.4; P = 0.01) short-term post-discharge mortality. Conclusions Persistent kidney dysfunction after an AKI episode is an independent predictor of 30-day post-discharge mortality. This information might help select AKI patients who require closer follow up and monitoring after discharge.