Performance of race-neutral eGFR equations in patients with decompensated cirrhosis.

The 2021 Chronic Kidney Disease Epidemiology Collaboration equation [CKD-EPI 2021] is a race-neutral equation recently developed and rapidly implemented as a reference standard to estimate glomerular filtration rate(GFR). However, its role in cirrhosis has not been examined especially in low GFR. We analyzed the performance of CKD-EPI 2021 compared to other equations with protocol measured GFR(mGFR) in cirrhosis. We analyzed 2090 unique adult patients with cirrhosis undergoing protocol GFR measurements using iothalamate clearance from 1985-2015 when listed for liver transplantation at Baylor University in Dallas and Fort Worth, Texas. Using mGFR as a reference standard, the CKD-EPI 2021 was compared to CKD-EPI 2012, MDRD-4, MDRD-6, RFH and GRAIL overall and in certain subgroups(ascites, mGFR≤30 mL/min/1.73 m2, diagnosis, MELD and gender). We examined bias(difference between eGFR and mGFR), accuracy(p30: eGFR within ±30% of mGFR) and agreement between eGFR and mGFR categories. CKD-EPI 2021 had the 2nd lowest bias across the entire range of GFR after GRAIL (6.6 vs. 4.6 mL/min/1.73 m2, respectively, p<0.001). Accuracy of CKD-EPI 2021 was similar to CKD-EPI 2012 (p30=67.8% vs. 67.9%, respectively) that was higher than the other equations (p<0.001). It had a similar performance in patients with ascites, by diagnoses, MELD subgroups, by sex and in non-Black patients. However, it had a relatively higher overestimation in mGFR≤30 mL/min/1.73 m2 than most equations (18.5 mL/min/1.73m2, p<0.001). Specifically, 64% of patients with mGFR≤30 mL/min/1.73m2 were incorrectly classified to a less severe CKD stage by CKD-EPI 2021. In Blacks, CKD-EPI 2021 underestimated eGFR by 17.9 mL/min/1.73 m2 that was higher than the alternate equations except RFH (p<0.001). The novel race-neutral eGFR equation, CKD-EPI 2021, improves the GFR estimation overall but may not accurately capture true kidney function in cirrhosis specifically at low GFR. There is an urgent need for a race-neutral equation in liver disease reflecting the complexity of kidney function physiology unique to cirrhosis given implications for organ allocation and dual organ transplant.