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Abstract: FR-OR14

Estimated Glomerular Filtration Rate Equations: Do We Need to Use the Ethnicity Correction Factor in People of African Ancestry Outside of the United States?

Session Information

Category: CKD (Non-Dialysis)

  • 2101 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

  • Gama, Rouvick, King’s Kidney Care, King's College Hospital, London, London, United Kingdom
  • Clery, Amanda, King's College London, London, London, United Kingdom
  • Palmer, Kieran R., King’s Kidney Care, King's College Hospital, London, London, United Kingdom
  • Kibble, Henry A., King’s Kidney Care, King's College Hospital, London, London, United Kingdom
  • Cairns, Hugh, King’s Kidney Care, King's College Hospital, London, London, United Kingdom
  • Sharpe, Claire C., King’s Kidney Care, King's College Hospital, London, London, United Kingdom
  • Peters, Adrien Michael, King's College London, London, London, United Kingdom
  • Heraghty, Neil, King's College London, London, London, United Kingdom
  • Bramham, Kate, King’s Kidney Care, King's College Hospital, London, London, United Kingdom
Background

Recent African studies suggest ethnicity factors in estimated glomerular filtration rate (eGFR) equations is not required.

Methods

To assess accuracy of eGFR equations, with and without ethnicity factors compared with gold standard 51Cr-ethylenediaminetetraacetic acid (51Cr-EDTA) clearance assays. Patients with albumin <30g/dl, hepatology referrals, <18 years old, non-white or black, mixed ethnicities were excluded. Accuracy of CKD-EPI and MDRD equations compared to 51Cr-EDTA GFR were assessed with and without correction factor.

Results

2,776 51Cr-EDTA studies were identified (Mean age-54yrs; 43% female; 12% Black ethnicity). In Black patients, CKD-EPI and MDRD eGFR equations significantly overestimated GFR compared to White (p<0.001) but without ethnicity correction factor estimates were considerably improved (p<0.001)(Table 1). Accuracy was superior for GFR≥60ml/min/1.73m2 compared to <60ml/min/1.73m2 using CKD-EPI equation for both White and Black patients (p<0.001).

Conclusion

Overestimation of measured GFR with eGFR equations using ethnicity correction factors identified in this study may lead to reduced rates of CKD diagnosis and under-recognition of CKD severity in people of Black ethnicity in the UK. These findings require prospective validation in other countries.

Table 1: Estimated Glomerular Filtration equations bias, precision and accuracy compared with 51Cr-EDTA clearance for people of Black and White ethnicities according to 51Cr-EDTA GFR categories
   GFR Mean (SD)BiasPrecisionLimits of agreement30% Accuracy (%)
BlackCorrected 51Cr-EDTA
GFR <60
(N=56)
Corrected 51EDTA41.0 (13.8)    
CKD-EPI adjusted59.4 (27.3)18.419.8-21.2 to 5839.3
CKD-EPI unadjusted51.2 (23.6)10.216.7-23.2 to 43.655.4
MDRD adjusted57.2 (24.8)16.217.5-18.8 to 51.248.2
MDRD unadjusted47.2 (20.5)6.214.1-22.0 to 34.464.3
Corrected 51Cr-EDTA ≥GFR 60
(N=249)
Corrected 51EDTA87.2 (16.0)    
CKD-EPI adjusted107.9 (22.3)20.721.9-23.1 to 64.559.4
CKD-EPI unadjusted93.1 (19.3)5.919.7-33.5 to 45.381.1
MDRD adjusted107.3 (30.2)20.128.1-36.1 to 76.359.4
MDRD unadjusted88.5 (24.9)1.323.7-46.1 to 48.777.5
WhiteCorrected 51Cr-EDTA
GFR <60
(N=399)
Corrected 51EDTA46.6 (11.2)    
CKD-EPI64.2 (21.2)17.616.1-14.6 to 49.844.1
MDRD61.4 (21.6)14.817.1-19.4 to 49.051.4
Corrected 51Cr-EDTA ≥GFR 60
(N=1568)
Corrected 51EDTA83.2 (15.4)    
CKD-EPI96.7 (16.0)13.514.9-16.3 to 43.374.4
MDRD97.7 (25.2)14.522.8-31.1 to 60.170.0

Adjusted = including ethnicity correction factor; Unadjusted = excluding ethnicity correction factor