Table 3.
Predictive performance of equations estimating glomerular filtration rate compared with creatinine clearance (CrCl24h-urine) measured by 24-hour urine collection.
| CrCl24h-urine | CGactual-wt | CGideal-wt | CGadjusted-wt | MDRD-4 | MDRD-6 | CKD-EPI | Jelliffe | ||
|---|---|---|---|---|---|---|---|---|---|
| Data from the first 237 urine collections (all 237 patients) | |||||||||
| GFR estimate (mlH/min) ±SD | 108.4 ± 68.9 | 129.6 ± 65.6 | 113.5 ± 59.2 | 119.9 ± 59.9 | 108.9 ± 52.5 | 102.2 ± 48.7 | 102.1 ± 40.4 | 102.0 ± 49.3 | |
| Coefficient of variation (%) | 63.6 | 50.6 | 52.2 | 50.0 | 48.2 | 47.7 | 39.6 | 48.3 | |
| Correlation | 0.77 | 0.71 | 0.75 | 0.63 | 0.62 | 0.67 | 0.66 | ||
| Bias (ml/min) | 21.1∗ | 5.0 | 11.5∗ | 0.5 | −10.5∗ | −6.3 | −6.4 | ||
| Precision (ml/min) | ±46.0 | ±49.9 | ±45.9 | ±54.2 | ±53.9 | ±51.6 | ±51.9 | ||
| Error (%) | 77.3 | 90.0 | 80.4 | 99.7 | 100.4 | 98.0 | 98.6 | ||
| Accuracy | |||||||||
| ±15% | 12.7 | 27.4 | 30.0 | 25.7 | 22.8 | 28.3 | 25.7 | ||
| ±30% | 49.4 | 48.1 | 51.2 | 48.9 | 47.4 | 48.9 | 49.4 | ||
| ±50% | 66.7 | 72.2 | 71.3 | 69.2 | 75.1 | 70.5 | 57.4 | ||
|
| |||||||||
| Data from the 453 urine collections (all 237 patients) | |||||||||
| GFR estimate (ml/min) ±SD | 102.7 ± 65.4 | 130.1 ± 65.9 | 114.9 ± 60.2 | 121.0 ± 60.6 | 109.8 ± 52.1 | 99.8 ± 47.1 | 103.2 ± 40.0 | 103.2 ± 49.3 | |
| Coefficient of variation (%) | 63.7 | 50.7 | 52.4 | 50.1 | 47.4 | 47.2 | 38.8 | 47.8 | |
| Correlation | 0.79 | 0.75 | 0.79 | 0.67 | 0.66 | 0.67 | 0.70 | ||
| Bias (ml/min) | 27.4∗ | 12.3∗ | 18.3∗ | 7.1∗ | −5.7∗ | 0.53 | 0.53 | ||
| Precision (ml/min) | ±43.0 | ±44.3 | ±40.9 | ±49.1 | ±49.3 | ±47.2 | ±46.8 | ||
| Error (%) | 73.9 | 81.5 | 73.2 | 92.5 | 96.1 | 91.8 | 90.9 | ||
|
| |||||||||
| Accuracy | |||||||||
| ±15% | 24.1 | 27.8 | 29.1 | 26.7 | 27.5 | 28.0 | 26.7 | ||
| ±30% | 42.8 | 47.5 | 49.2 | 49.9 | 50.5 | 50.3 | 50.8 | ||
| ±50% | 60.0 | 69.3 | 66.2 | 69.3 | 73.5 | 69.8 | 72.2 | ||
|
| |||||||||
| Urine collections with CrCl 24h-urine < 30 ml/min (N = 72) | |||||||||
| GFR estimate (ml/min) ±SD | 13.3 ± 8.4 | 39.7 ± 25.7 | 30.8 ± 25.7 | 34.4 ± 25.6 | 34.4 ± 33.3 | 32.1 ± 28.4 | 38.2 ± 30.6 | 33.7 ± 27.9 | |
| Coefficient of variation (%) | 63.2 | 64.7 | 83.4 | 74.4 | 96.8 | 88.5 | 80.1 | 82.8 | |
| Correlation | 0.58 | 0.50 | 0.54 | 0.55 | 0.58 | 0.56 | 0.54 | ||
| Bias (ml/min) | 26.4∗ | 17.6∗ | 21.1∗ | 21.1∗ | 18.7∗ | 25.0∗ | 20.4∗ | ||
| Precision (ml/min) | ±21.9 | ±22.7 | ±21.8 | ±29.5 | ±24.4 | ±26.9 | ±24.4 | ||
|
| |||||||||
| Accuracy | |||||||||
| ±15% | 1.4 | 16.7 | 5.6 | 12.5 | 13.1 | 11.1 | 8.3 | ||
| ±30% | 6.9 | 23.6 | 15.3 | 26.4 | 27.9 | 23.6 | 19.4 | ||
| ±50% | 11.1 | 36.1 | 23.6 | 36.1 | 39.3 | 30.6 | 31.9 | ||
|
| |||||||||
| Urine collections with CrCl 24h-urine 30–59.9 ml/min (N = 68) | |||||||||
| GFR estimate (ml/min) ±SD | 45.3 ± 8.6 | 85.6 ± 34.5 | 76.9 ± 37.3 | 80.4 ± 35.4 | 84.8 ± 40.6 | 73.8 ± 36.5 | 86.3 ± 29.5 | 76.0 ± 35.3 | |
| Correlation | 0.44 | 0.46 | 0.46 | 0.30 | 0.46 | 0.35 | 0.33 | ||
| Coefficient of variation (%) | 19.0 | 40.3 | 48.5 | 44.0 | 47.9 | 49.5 | 34.2 | 46.4 | |
| Bias (ml/min) | 40.3∗ | 31.6∗ | 35.1∗ | 39.5∗ | 28.4∗ | 41.0∗ | 30.6∗ | ||
| Precision (ml/min) | ±31.7 | ±34.3 | ±32.4 | ±38.9 | ±33.5 | ±27.6 | ±33.5 | ||
|
| |||||||||
| Accuracy | |||||||||
| ±15% | 5.9 | 11.8 | 14.7 | 7.4 | 15.5 | 7.4 | 11.8 | ||
| ±30% | 16.2 | 26.5 | 25.0 | 20.6 | 32.8 | 14.7 | 35.3 | ||
| ±50% | 27.9 | 44.1 | 39.7 | 38.2 | 53.4 | 23.5 | 51.5 | ||
|
| |||||||||
| Urine collections with CrCl 24h-urine 60–129.9 ml/min (N = 156) | |||||||||
| 97.8 ± 20.5 | 134.2 ± 44.5 | 121.6 ± 43.8 | 126.6 ± 41.9 | 120.8 ± 37.6 | 107.7 ± 35.5 | 114.2 ± 26.4 | 111.7 ± 36.2 | ||
| Coefficient of variation (%) | 21.0 | 33.2 | 36.0 | 33.1 | 31.1 | 33.0 | 23.1 | 32.4 | |
| Correlation | 0.37 | 0.38 | 0.40 | 0.12 | 0.18 | 0.32 | 0.23 | ||
| Bias (ml/min) | 36.4∗ | 23.8∗ | 28.8∗ | 23.0∗ | 9.6∗ | 16.4∗ | 13.9∗ | ||
| Precision (ml/min) | ±41.6 | ±40.6 | ±38.7 | ±40.7 | ±37.6 | ±20.7 | ±37.2 | ||
|
| |||||||||
| Accuracy | |||||||||
| ±15% | 24.4 | 27.6 | 29.5 | 27.6 | 32.6 | 42.3 | 28.8 | ||
| ±30% | 44.2 | 46.2 | 49.4 | 53.8 | 54.5 | 61.5 | 55.8 | ||
| ±50% | 66.7 | 71.8 | 69.2 | 72.4 | 73.1 | 84.0 | 78.8 | ||
|
| |||||||||
| Urine collection with CrCl 24h-urine > 130 ml/min (N = 157) | |||||||||
| GFR estimate (ml/min) ±SD | 173.3 ± 41.6 | 186.6 ± 44.2 | 163.3 ± 37.6 | 172.6 ± 34.3 | 144.1 ± 32.3 | 130.3 ± 30.5 | 129.4 ± 16.3 | 138.4 ± 31.3 | |
| Coefficient of variation (%) | 24.0 | 23.7 | 23.0 | 19.9 | 22.4 | 23.4 | 12.6 | 22.6 | |
| Correlation | 0.29 | 0.20 | 0.28 | 0.22 | 0.14 | 0.14 | 0.20 | ||
| Bias (ml/min) | 13.3∗ | −10.0∗ | −0.7 | −29.2∗ | −43.7∗ | −44.0∗ | −34.9∗ | ||
| Precision (ml/min) | ±51.3 | ±50.0 | ±45.8 | ±46.7 | ±48.2 | ±42.5 | ±46.8 | ||
|
| |||||||||
| Accuracy | |||||||||
| ±15% | 42.0 | 40.1 | 45.9 | 40.8 | 33.1 | 30.6 | 39.5 | ||
| ±30% | 69.4 | 68.8 | 75.2 | 69.4 | 57.4 | 66.9 | 66.9 | ||
| ±50% | 89.8 | 93.0 | 94.3 | 94.9 | 88.5 | 93.6 | 93.0 | ||
CKD-EPI: chronic kidney disease epidemiology collaboration; CG: Cockroft-Gault; CrCl24h-urine: creatinine clearance measured by 24-hour urine collection; GFR: glomerular filtration rate; MDRD: modification of diet in renal disease study; SD: standard deviation. CGactual-wt: the CG equation was calculated using actual body weight. CGideal-wt: the CG equation was calculated using ideal body weight. CGadjusted-wt: the CG equation was calculated using adjusted body weight. MDRD-4: the MDRD equation was calculated using four variables. MDRD-6: the MDRD equation was calculated using six variables. ∗p < 0.05 using one-sided t test indicating that the bias was significant.