Total Kidney Volume and Recovery of Kidney Function in AKI Patients with Kidney Replacement Therapy

Background: Among patients with acute kidney injury (AKI), 10% require renal replacement therapy (RRT), and 15% progress to end-stage renal disease (ESRD) with higher in-hospital mortality. While preexisting chronic kidney disease (CKD) is a risk factor for progression from AKI to ESRD, assessing preexisting CKD at AKI onset is challenging. Total kidney volume (TKV) is known to decrease in CKD. The aim of this study is to investigate whether TKV can predict kidney function recovery in AKI patients. Methods: We retrospectively investigated AKI patients who required more than three times of RRT from April 2003 to November 2023. Exclusions criterion were the patients with post-kidney transplantation, with polycystic kidney disease, without CT imaging six months before admission, with unmeasurable TKV on CT, or with vascular access for maintenance hemodialysis. The primary outcome was RRT discontinuation within 90 days and no need for RRT for two weeks after discontinuation. TKV was measured using SYNAPSE VINCENT(R) from CT images. Clinical characteristics and laboratory data at RRT initiation were extracted. Results: Among 446 patients (71.7% male, mean age 68.3 years, mean hospital stay 90.0 days), 179 (40.1%) discontinued RRT within 90 days. In-hospital mortality was significantly lower in the discontinuation group (64.0% vs 17.9%, p<0.001). In multivariate Cox regression analysis with age, sex, TKV, suppressor use, diabetes mellitus (DM), cancer, AKI after surgery, AKI due to acute tubular necrosis, serum albumin and hemoglobin as independent variables, TKV [ml], DM and hemoglobin [g/dl] were significantly associated with dialysis discontinuation (hazard ratio 1.00, 0.70 and 1.11, respectively; 95% confidence interval 1.001 to 1.004, 0.51 to 0.97 and 1.04 to 1.18, respectively). Conclusion: TKV may predict renal function recovery, offering broader management strategies.