Keywords:
CT, Kidney, Contrast agents, Laboratory tests, Drugs / Reactions
Authors:
A. Wibmer1, R. Nolz1, G. Heinz-Peer2; 1Wien/AT, 2St. Pölten/AT
DOI:
10.1594/ecr2013/C-2669
Results
The laboratory gold standard yielded a significantly higher mean eGFR value when compared to the capillary and venous blood analysis of the StatSensor® (p<0.001,
respectively).
Agreement plots and Bland-Altman plots are for the venous measurements are shown in Figures 1 and 2,
those for the capillary measurement are shown in Figure 3 and 4.
These plots show a good agreement of eGFR-values calculated on the basis of the StatSensor® creatinine measurements and the gold standard.
This was especially true for patients with an eGFR<90 ml/min/1.73m².
Diagnostic accuracy of the StatSensor® was evaluated by its potential to discriminate patients with normal from those with abnormal renal function,
with an eGFR of 30,
45 and 60 ml/min/1.73m² as cut-off,
respectively.
Table 2 gives information about sensitivity,
specificity,
positive and negative predictive values and accuracy when compared to the gold-standard.
Sample
|
Cut-off eGFR (ml/min/1.73m²)
|
Sensitivity
|
Specificity
|
ppV
|
npV
|
Accuracy
|
Capillary Blood
|
60
|
0.87
|
0.87
|
0.62
|
0.96
|
0.87
|
45
|
1.00
|
0.95
|
0.60
|
1.00
|
0.96
|
30
|
1.00
|
0.99
|
0.40
|
1.00
|
0.99
|
Venous Blood
|
60
|
0.85
|
0.90
|
0.67
|
0.96
|
0.89
|
45
|
1.00
|
0.96
|
0.63
|
1.00
|
0.96
|
30
|
1.00
|
0.99
|
0.43
|
1.00
|
0.99
|
It shows a 100% sensitivity for the detection of patients with an eGFR <30 and <45 ml/min/1.73m²,
while sensitivity was lower if a cut-off eGFR of 60 ml/min/1.73m² was chosen.
Negative predictive value was >96% for all three cut-off eGFR values,
for capillary as well as venous blood analysis.
Specificity ranged from 87% to 99%,
depending on the eGFR cut-off value.
Positive predictive values varied between 40% and 67%.