Table 2:
Bias, precision and accuracy of the four GFR estimating equations.
| Subjects and criteria | CKD-EPI 2009 equation | CKD-EPI 2021 equation | Creatinine clearance | Urea clearance | Average of creatinine and urea clearances |
|---|---|---|---|---|---|
| Population = 855 | |||||
| Median bias (95% CI) | −3.7 (−4.7; −2.5) | −6.6 (−7.8; −5.5) | −14.0 (−14.0; −13.0)* | 26.0 (25.0; 27.0)* | 5.5 (4.5; 6.0) |
| IQR (95% CI) | 19.0 (17.2; 20.1) * | 19.1 (17.4; 20.4)* | 14.0 (13.0; 15.0)* | 20.0 (18.0; 21.0)* | 11.5 (10.5; 12.5) |
| P10 (95% CI) | 37.1 (33.8; 40.5)* | 36.3 (33.1; 39.4)* | 19.7 (17.2; 22.5)* | 0.8 (0.02; 1.5)* | 48.0 (44.5; 51.2) |
| P30 (95% CI) | 82.0 (79.2; 84.4)* | 77.2 (74.5; 80.0)* | 66.0 (62.8; 69.2)* | 20.1 (17.5; 22.9)* | 97.0 (95.8; 98.0) |
| CCC (95% CI) | 0.844 (0.824; 0.862) | 0.825 (0.803; 0.844)* | 0.825 (0.807; 0.841)* | 0.599 (0.573; 0.624)* | 0.941 (0.933; 0.948) |
| RMSE (95% CI) | 0.234 (0.220; 0.254) | 0.235 (0.221; 0.254) | 0.159 (0.149; 0.171) | 0.149 (0.141; 0.160) | 0.130 (0.122; 0.146) |
| Agreementa (%) | 59.7 (56.6; 63.2)* | 59.3 (56.0; 62.5)* | 54.4 (51.0; 57.8)* | 9.5 (7.7; 11.6)* | 70.3 (67.1; 73.3)* |
Bias is defined as the median difference between mGFR and eGFR. A positive sign indicates underestimation of mGFR, and a negative sign indicates overestimation of mGFR. P10 and P30 are the proportion of eGFR within 10% and 30% of mGFR, respectively.
aAgreement: correct classification refers to agreement between mGFR and eGFR categories of ≥90, 60–89, 45–59, 30–44 and <30 mL/1.73 m2.
*P < .005 between average clearance creatinine–urea and others eGFR.