Validation of Combining Total Kidney Volume and Kidney Failure Risk Equation in Autosomal Dominant Polycystic Kidney Disease

IntroductionTotal kidney volume (TKV) interpreted via the Mayo Imaging Classification (MIC) is the recommended prognostication tool in autosomal dominant polycystic kidney disease (ADPKD), but further risk stratification is often needed.The kidney failure risk equation (KFRE) is validated in CKD of diverse etiologies, but its use in ADPKD patients already assessed via the MIC is unclear.This study evaluated the impact of adding KFRE to MIC. MethodsAdults with ADPKD with 1 CT or MRI derived TKV available between January 2015 and January 2023 were included in this retrospective observational study.The predictive performance of models including the MIC value, baseline eGFR, and 5-year KFRE score, and fully adjusted models were examined using the composite outcome of kidney replacement therapy initiation or eGFR decline 40%.The primary analysis was in patients with eGFR <60 mL/min/1.73m 2 . ResultsIn the eGFR <60 mL/min/1.73m 2 group, compared to the model with MIC value alone, the adjusted model including age, sex, Tolvaptan, KFRE and MIC value demonstrated the best performance (AIC = 631, C-statistic = 0.47, 0.28 and 0.27 at 1, 3 and 5 years respectively), followed closely by the combination of MIC value and KFRE (AIC = 641, C-statistic = 0.47, 0.26 and 0.26), KFRE alone (AIC = 642, C-statistic = 0.47, 0.26 and 0.28) at 1, 3 and 5 years respectively. ConclusionsIn the cohort with a baseline eGFR <60 mL/min/1.73m 2 , use of the KFRE in addition to the MIC improved risk prediction, supporting the utilization of these tools together in ADPKD.