External Validation of a Novel Multimarker GFR Estimating Equation.

Abstract

Using multiple markers may improve accuracy in glomerular filtration rate (GFR) estimation. We sought to externally validate and compare the performance a novel multi-marker estimated GFR (panel eGFR) among Black and White persons using the Genetic Epidemiology Network of Arteriopathy cohort. We included 224 sex, race/ethnicity, and measured GFR (mGFR)-category-matched persons, with GFR measured using urinary clearance of iothalamate. We calculated panel eGFR using serum creatinine, valine, myo-inositol, cystatin C, age, and sex. We compared its reliability with current eGFR equations (2021 CKD-EPI creatinine [eGFR-Cr] and creatinine with cystatin C [eGFR-Cr-CysC]) using median bias, precision, and accuracy metrics. We evaluated each equation's performance in age, sex, and race subgroups. In the overall cohort, 49% were Black individuals and mean mGFR was 79 ml/min/1.73m2. Panel eGFR overestimated mGFR (bias: -2.4 ml/min/1.73m2; 95% confidence interval [CI]: -4.4, -0.7), eGFR-Cr-CysC underestimated mGFR (bias: 4.8 ml/min/1.73m2; 95% CI: 2.1, 6.7), while eGFR-Cr was unbiased (bias: 2.0 ml/min/1.73m2; 95% CI: -1.1, 4.6). All equations had comparable accuracy. Among Black males age <65 years, both eGFR-Cr (bias: 17.0 ml/min/1.73m2; 95% CI: 8.6, 23.5) and eGFR-Cr-CysC (bias: 14.5 ml/min/1.73m2; 95% CI: 6.0, 19.7) underestimated mGFR whereas panel eGFR was unbiased (bias: 1.7 ml/min/1.73m2; 95% CI: -3.4, 10.0). Metrics of accuracy for all eGFRs were acceptable in all subgroups except for panel eGFR in Black females <65 years (P30: 73.3%). Panel eGFR can be used to estimate mGFR and may have utility among Black males age <65 years where current CKD-EPI equations are biased.