Survival after acute kidney injury requiring dialysis: long-term follow up

Data on long-term follow up after acute kidney injury (AKI) requiring dialysis are scarce. The aim of this study was to describe and identify factors associated with survival, recovery of kidney function at discharge, and long-term follow up of renal function in AKI patients requiring dialysis. All AKI patients requiring dialysis during calendar year 2000-2011 treated with conventional hemodialysis and daily shift continuous venovenous hemodialysis (8-hour 40 L dialysate) were included. The data were mean and SD. The results were: 65.8% male; 33.9% diabetic; 75% dipstick positive proteinuria on admission; 72.5% medical AKI; and 27.6% surgical AKI of those (14.2%) who had postcardiovascular surgery. At discharge mortality by cause of AKI: medical 25%, surgical 29.8%; and at the end of study: medical 35.3%, surgical 43.6%. Two-hundred thirty-four patients were discharged alive (mortality 26%). Forty-two died after discharge; 50% in the first 156 days post discharge. Mortality at the end of study was 37.8%. Follow-up (F/U) (1-86 m). At discharge, 200 recovered from kidney function (63.2%), and of those who died in the hospital 80.5% did not recover from kidney function (died dialysis dependent). Baseline serum creatinine was 1.33 mg/dL (0.64), estimated glomerular filtration rate (eGFR) 63.4 mL/minute (29.3), peak creatinine 6.3 mg/dL (2.9), and peak blood urea nitrogen 88.1 mg/dL (39.9). At discharge, serum creatinine was 3.1 mg/dL (2.1) and eGFR was 31.6 mL/minute (27.4); at 6 months, creatinine was 1.66 mg/dL (1.1) and eGFR was 60.8(36); at all F/U times, the creatinine was higher and eGFR was lower than the baseline values (P < 0.05). Of the nonsurvivors, the only significant difference was a lower albumin at baseline (2.9 vs. 3.1 g/dL) (P < 0.05) and lower peak creatinine (5.5 vs. 6.8 mg/dL) (P < 0.05). The mean survival time was 45.4 months. The survival of the patients who recovered from kidney function at discharge was longer than the ones who did not recover (59.7 vs. 16 m, P < 0.05). By Cox regression, the factors significant for survival were peak creatinine and status at discharge. During follow up (data up to 54 months), the percentage of patients with eGFR < 60 mL/minute decreased from 90.9% at discharge to 63.6% at 24 months, then increased to 81.8% at 30 months and longer. The percentage of patients with eGFR < 30 mL/minute decreased from 45.4% at discharge to 18.2% at 24 months to increase at a later date (27-36%). The percentage of patients with eGFR < 15 mL/minute decreased from 45.45% at discharge to 18% until 24 months of follow up (to increase to 27.7% at later dates). AKI requiring dialysis has a significant effect on GFR with almost 80% of the survivors having chronic kidney disease stage 3 or worse. Furthermore, progression was observed on the long-term follow up. Factors affecting the survival included peak creatinine and status of recovery of kidney function at discharge.