Long-term functional evolution after an acute kidney injury: a 10-year study

Background. Data on long-term effects of acute kidney injury (AKI) on renal function (RF) are scarce and factors implicated in the functional outcome are not established. Our aim was to investigate these aspects. Methods. At hospital discharge and annually for 10 years, we retrospectively reviewed RF of 187 patients surviving AKI. Glomerular filtration rates estimated with MDRD equation (eGFR) and KDOQI stages were used to evaluate RF. Only 34.8% of patients had pre-existing renal dysfunction (KDOQI-3). Variables determining long-term RF were collected during AKI and at discharge and analysed with a regression model. Results. At discharge no patient necessitated dialysis, but eGFR was lower than baseline (47.5 +/- 23.3 ml/min/ 1.73 m(2) versus 75.8 +/- 25.4 ml/min/1.73 m(2)); 38.4% of survivors had recovered basal RF: 26% of those with previous normal RF and 61% of those in KDOQI-3, respectively. At 1 year, eGFR increased to 61.9 +/- 24.4 ml/min/1.73 m(2) and remained stable later. During an 8-year median follow-up (P25:2; P75:10), 31% improved RF, 50% remained stable and 19% deteriorated. In total only 46% (n = 82) definitively recovered RF. Finally, at the end of the study period 61.6% presented some degree of renal dysfunction: 40% of those with previous normal RF developed moderate-severe renal dysfunction and 37% KDOQI-3 progressed into more severe renal failure. Only two patients needed dialysis. Regression model identified age, co-morbidities, discharge eGFR and follow-up time as independent predictors of long-term RF. Conclusions. AKI carries implication for long-term RF even in patients without pre-existing renal dysfunction. Ageing, co-morbidities and RF at discharge are determinants of the long-term functional outcome.