Overall performance of eGFR equations compared with rGFR: Difference, absolute difference, bias, precision, and accuracya
| Parameter | Equation 1 | Equation 2 | Equation 3 | Equation 4 | Equation 5 | Equation 6 |
|---|---|---|---|---|---|---|
| Intercept (95% CI) | 6.45 (3.78 to 9.84) | 6.58 (3.75 to 9.39) | 7.76 (4.54 to 10.98) | 8.06 (4.61 to 11.53) | 8.55 (5.45 to 11.64) | 9.54 (6.26 to 12.81) |
| Slope (95% CI) | 0.69 (0.65 to 0.74) | 0.68 (0.64 to 0.72) | 0.84b (0.78 to 0.88) | 0.83b (0.78 to 0.88) | 0.82b (0.77 to 0.87) | 0.81b (0.76 to 0.85) |
| R | 0.91 | 0.90 | 0.91 | 0.90 | 0.92 | 0.91 |
| R2 | 0.84 | 0.81 | 0.84 | 0.81 | 0.84 | 0.82 |
| Median of difference (ml/min per 1.73 m2; 25%, 75% percentile) | −7.4 (−19.5, −1.3) | −7.8 (−21.5, −1.8) | −0.3b (−8.5, 6.3) | −0.9b (−9.6, 7.4) | −0.8b (−9.7, 7.4) | −0.8b (−9.7, 7.4) |
| Median of absolute difference (ml/min per 1.73 m2; 25%, 75% percentile) | 8.7 (3.7, 19.5) | 9.4 (4.2, 21.5) | 7.3b (2.7, 15.1) | 8.8b (3.3, 15.2) | 7.1b (2.7, 15.6) | 7.9b (3.3, 15.6) |
| Bias (arbitrary units) | 2133.9 | 2175.0 | 605.8 | 543.0 | 685.6 | 677.2 |
| Precision (ml/min per 1.73 m2; %) | 57.6 | 60.7 | 54 | 57.5 | 53.2 | 56.5 |
| 15% accuracy | 32.6 | 30.0 | 50.4b | 48.7b | 47.4b | 46.9b |
| 30% accuracy | 70.4 | 66.1 | 76.1 | 77.8b | 79.6b | 79.6b |
| 50% accuracy | 95.2 | 93.9 | 93.9 | 92.2 | 93.5 | 93.0 |
↵a The estimated GFR (eGFR) that resulted from these six equations all were significantly correlated with rGFR. Linear regressions were made using eGFR against rGFR. The six intercepts were much similar, but the slopes of equations 3 through 6 were significantly closer to the identical line compared with the slopes of equations 1 and 2. CI, confidence interval.
↵b P < 0.05 compared with equations 1 and 2.