Table 2.
eGFR and bias of Chronic Kidney Disease Epidemiology Collaboration and European Kidney Function Consortium eGFR creatinine, cystatin C, and creatinine–cystatin C equations in the overall study population and in subgroups of race, sex, and age
| Equations | eGFR | Bias | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Overall Group | Overall Group | Race Subgroups | Sex Subgroups | Age Subgroups | |||||
| Black | Non-Black | Female | Male | <40 | 40–65 | >65 | |||
| N (%) | 4050 (100) | 4050 (100) | 579 (14.3) | 3471 (85.7) | 1557 (38.4) | 2493 (61.6) | 715 (17.7) | 1989 (49.1) | 1346 (33.2) |
| Creatinine | |||||||||
| CKD-EPI 2021 (AS) | 78.8 (27.3) | −3.1 (−3.5 to −2.6) | 3.6 (1.8 to 5.5)a | −3.9 (−4.4 to −3.5)a | −5.4 (−6.3 to −4.6)a | −1.7 (−2.2 to −1.1)a | −2.1 (−3.2 to −0.8)a | −1.3 (−1.9 to −0.5)a | −5.6 (−6.2 to −4.8)a |
| CKD-EPI 2009 (ASR-NB) | 75.2 (27.0) | 0.4 (0.0 to 0.8) | 7.1 (5.9 to 8.8)a | −0.5 (−0.9 to 0.0)a | −1.9 (−2.6 to −1.3) | 1.8 (1.2 to 2.2) | 0.2 (−1.3 to 1.2) | 2.0 (1.3 to 2.6) | −1.4 (−1.8 to −0.9) |
| EKFC 2021 (AS) | 71.6 (25.3) | 3.5 (3.1 to 3.9) | 9.2 (7.8 to 10.8)a | 2.8 (2.4 to 3.2)a | 2.1 (1.5 to 2.8) | 4.4 (3.8 to 5.0) | 3.6 (2.5 to 5.4) | 3.4 (2.8 to 4.0) | 3.6 (3.1 to 4.1) |
| Cystatin C | |||||||||
| CKD-EPI 2012 (AS) | 75.0 (29.4) | 0.6 (0.1 to 1.1) | −0.1 (−1.5 to 1.6) | 0.7 (0.2 to 1.2) | −1.1 (−1.8 to −0.5) | 1.8 (1.2 to 2.5) | −1.3 (−3.5 to 0.2) | 0.7 (−0.1 to 1.7) | 1.0 (0.5 to 1.6) |
| CKD-EPI 2023 (A) | 74.8 (29.2) | 0.9 (0.3 to 1.3) | 1.3 (−0.6 to 2.6) | 0.8 (0.2 to 1.3) | −3.7 (−4.5 to −3.0)a | 3.6 (3.0 to 4.3)a | −1.9 (−3.4 to 0.2) | 1.5 (0.8 to 2.2) | 0.7 (0.0 to 1.6) |
| EKFC 2023 (A) | 73.5 (25.0) | 1.2 (0.6 to 1.6) | 2.1 (0.7 to 3.8) | 1.0 (0.4 to 1.5) | −3.0 (−3.7 to −2.2)a | 4.0 (3.4 to to 4.5)a | −1.1 (−2.5 to 0.7) | 1.9 (1.0 to 2.6) | 1.1 (0.4 to 1.5) |
| Creatinine–cystatin C | |||||||||
| CKD-EPI 2021 (AS) | 78.4 (28.7) | −2.5 (−2.9 to −2.1) | 0.1 (−0.9 to 1.6) | −2.9 (−3.3 to −2.5) | −4.5 (−5.2 to −3.9) | −1.2 (−1.7 to −0.6) | −2.4 (−3.7 to −0.4) | −1.2 (−1.8 to −0.6) | −3.9 (−4.3 to −3.3) |
| CKD-EPI 2012 (ASR-NB) | 75.8 (28.3) | −0.1 (−0.5 to 0.2) | 3.4 (1.5 to 4.5) | −0.6 (−0.9 to −0.1) | −2.0 (−2.9 to −1.5) | 1.1 (0.7 to 1.6) | −0.9 (−2.4 to 0.7) | 1.0 (0.4 to 1.5) | −1.0 (−1.4 to −0.7) |
| EKFC 2023 (AS) | 72.5 (24.4) | 2.2 (1.8 to 2.6) | 5.8 (4.3 to 7.1)a | 1.6 (1.2 to 2.1)a | −0.7 (−1.4 to −0.1) | 4.0 (3.4 to 4.3) | 1.1 (−0.3 to 2.4) | 2.4 (1.7 to 3.1) | 2.2 (1.7 to 2.8) |
eGFR is mean (SD). Systematic error (bias) was expressed as the median difference (95% confidence intervals) between measured GFR and eGFR. Unit for eGFR and bias is ml/min per 1.73 m2. A positive value for bias indicates eGFR underestimates measured GFR, and a negative value indicates eGFR overestimates measured GFR. Bias closer to zero is optimal. For eGFRcr and eGFRcr-cys, we implemented the EKFC equations using the creatinine Q values for White Europeans and CKD-EPI ASR equations using the NB coefficient for race to avoid specification of race for individual participants. CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; A, age; S, sex; R, race; B, Black; NB, non-Black; EKFC, European Kidney Function Consortium; mGFR, measured GFR.
It indicates bias >±5 for one or more subgroups or differential bias within subgroups >±5.