Estimation of glomerular filtration rate in patients with cirrhosis: evaluation of equations currently used in clinical practice and validation of Royal Free Hospital cirrhosis glomerular filtration rate

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 to 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, Modification of Diet in Renal Disease-4, Modification of Diet in Renal Disease-6, Royal Free Hospital, and GFR Assessment in Liver disease overall and in certain subgroups (ascites, mGFR ≤ 30 mL/min/1.73 m 2 , diagnosis, Model for End-Stage Liver Disease 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 second lowest bias across the entire range of GFR after GFR Assessment in Liver disease (6.6 vs. 4.6 mL/min/1.73 m 2 , respectively, p < 0.001). The accuracy of CKD-EPI 2021 was similar to CKD-EPI 2012 (p30 = 67.8% vs. 67.9%, respectively) which was higher than the other equations ( p < 0.001). It had a similar performance in patients with ascites, by diagnoses, Model for End-Stage Liver Disease subgroups, by gender, and in non-Black patients. However, it had a relatively higher overestimation in mGFR ≤ 30 mL/min/1.73 m 2 than most equations (18.5 mL/min/1.73m 2 , p < 0.001). Specifically, 64% of patients with mGFR ≤ 30 mL/min/1.73m 2 were incorrectly classified as a less severe CKD stage by CKD-EPI 2021. In Blacks, CKD-EPI 2021 underestimated eGFR by 17.9 mL/min/1.73 m 2 , which was higher than the alternate equations except for Royal Free Hospital ( 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.

Assessment of glomerular filtration rate in patients with cirrhosis: Available tools and perspectives

Renal dysfunction often complicates the course of liver disease, resulting in higher morbidity and mortality. The accurate assessment of kidney function in these patients is essential to early identify, stage and treat renal impairment as well as to better predict the prognosis, prioritize the patients for liver transplantation and decide whether to opt for simultaneous liver-kidney transplants. This review analyses the available tools for direct or indirect assessment of glomerular filtration rate, focusing on the flaws and strengths of each method in the specific setting of cirrhosis. The aim is to deliver a clear-cut view on this complex issue, trying to point out which strategies to prefer in this context, especially in the peculiar setting of liver transplantation. Moreover, a glance is given at future promising tools for glomerular filtration rate assessment, including new biomarkers and new equations specifically modelled for the cirrhotic population.