The Performance of Equations That Estimate Glomerular Filtration Rate against Measured Urinary Creatinine Clearance in Critically Ill Patients
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 CrCl24h-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 CrCl24h-urine30–59.9 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 CrCl24h-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 CrCl24h-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. using one-sided t test indicating that the bias was significant.
