Comparing five equations to estimate glomerular filtration rate or creatinine clearance and assign individuals to KDIGO categories across the full age spectrum using real world data

Abstract

Abstract Five equations are commonly used by biopharma companies to estimate glomerular filtration rate (GFR) or creatinine clearance (CrCl) based on regulatory and stakeholder recommendations. Changes observed in GFR and/or CrCl can be challenging to interpret as participants transition between age strata, prompting changes in equations. This manuscript explores how GFR, CrCl, and the resulting Kidney Disease Improving Global Outcomes (KDIGO) categories of kidney function can change when different equations are used. We analyzed descriptively real‐world data (RWD) from 48 health care organizations in the United States to identify patients with data (age, sex, height, weight, serum biomarkers such as creatinine [Scr] and/or cystatin C [Scys]) sufficient to estimate GFR and/or CrCl. Five equations (Bedside Schwartz, Modified Schwartz, Cockcroft‐Gault, 2021 Chronic Kidney Disease‐Epidemiology Collaboration [CKD‐EPI] Scr, and 2021 CKD‐EPI Scr/Scys) were used to estimate GFR and/or CrCl and assign individuals to KDIGO categories (G1–G5). We identified 32,728 patients, including 378 infants (<2 years), 1191 younger children (2 to <6 years), 1891 older children (6 to <12 years), 3174 adolescents (12 to <18 years), 16,367 younger adults (18 to <65 years), and 9727 older adults (65+ years) with sufficient information to estimate kidney function. For patients greater than or equal to 2 years, estimated GFR and/or CrCl and KDIGO categories based on the 2021 CKD‐EPI Scr/Scys equation appeared similar to those based on currently recommended equations. RWD suggests the 2021 CKD‐EPI Scr/Scys equation could potentially be used to estimate GFR in individuals aged 2 years and older; more research is needed to confirm these findings.