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Table 2 Performance of dual- and single- sampling methods at different GFR levelsa

From: Accuracy of iohexol plasma clearance for GFR-determination: a comparison between single and dual sampling

Variable mGFR (ml/min/1.73m2)
< 60 (n = 58) 60–89 (n = 42) > 90 (n = 70)
Bias ─ Mean Difference (95% CI)
 GFR23 1.05 (−0.10,1.7) −0.17 (− 1.29,0.11) −0.47 (− 1.10,-0.10)
 GFR34 − 0.75 (−1.3,-0.19) 0.35 (− 1.29,1.63) 2.71 (0.83,4.85)
 GFR24 − 0.02 (− 0.12,0.02) −0.73 (− 1.15,0.09) −0.86 (− 1.30,-0.28)
 GFR2 − 0.88 (−4.39,4.51) 0.04 (− 1.64,2.27) 1.19 (− 0.04,1.75)
 GFR3 1.31 (− 1.38,4.69) 1.76 (0.91,2.74) −1.73 (− 3.54,0.26)
 GFR4 0.43 (− 0.57,1.74) 0.40 (− 0.95,1.83) −5.89 (−7.95,3.76)
Precision ─ IQR (95% CI)
 GFR23 5.56 (1.82,8.73) 3.92 (1.25,7.18) 1.79 (1.30,3.03)
 GFR34 3.59 (1.36,7.21) 3.75 (1.39,9.56) 7.02 (4.64,12.64)
 GFR24 0.71 (0.21,1.39) 1.79 (0.88,3.10) 1.84 (1.17,2.89)
 GFR2 21.99 (9.43,32.91) 5.35 (3.24,12.48) 3.45 (2.16,5.02)
 GFR3 9.94 (6.26,14.68) 4.68 (1.36,6.84) 6.99 (4.15,11.14)
 GFR4 4.93 (2.58,9.27) 3.89 (2.40,12.12) 9.18 (4.96,14.11)
Accuracyb ─ % (95% CI)
P30
 GFR23 96.8 (87.9100) 100c 100c
 GFR34 91.4 (82.8,98.3) 100c 98.6 (95.7100)
 GFR24 100c 100c 100c
 GFR2 55.2 (43.1,69.0) 97.6 (92.9100) 100c
 GFR3 72.4 (60.3,84.5) 100c 100c
 GFR4 82.8 (72.4,91.4) 100c 100c
P10
 GFR23 60.34 (46.6,72.4) 92.9 (85.7100) 97.1 (92.9100)
 GFR34 65.5 (53.5,77.6) 83.3 (71.4,92.9) 87.1 (78.6,94.3)
 GFR24 100c 100c 98.6 (95.7100)
 GFR2 25.9 (13.8,36.2) 78.6 (66.7,90.5) 97.1 (92.9100)
 GFR3 41.4 (29.3,55.2) 90.5 (81.0,97.6) 92.9 (87.1,98.6)
 GFR4 65.5 (51.8,77.6) 88.1 (78.6,97.6) 78.6 (68.6,88.6)
  1. aGFRix or GFRi: i and x implies the sampling time (hr) of the blood used to calculate the corresponding plasma clearance of iohexol. Units are in ml/min/1.73m2
  2. bAccuracy was calculated as the percentage of estimate within 30% of the measured GFR (P30) and the percentage of estimate within 10% of the measured GFR (P10)
  3. cAs for accuracy, the value 100 represents none of the estimates differed from the mGFR by more than 30% or 10% with a 95% CI of (100,100)