Table 3.

Diagnostic performance of 24-hr UFC measured by the six methods

24-hr UFC	AUC	95% CI for AUC	Sensitivity (%)	Specificity (%)	Cut-off (nmol/24 hrs)
LC-MS/MS	0.972*	0.948–0.987	93.2	95.4	154.8
Abbott-D	0.975†	0.952–0.989	93.2	95.9	225.2
Beckman-D	0.877‡	0.837–0.911	76.1	94.6	1,321.5
Siemens-D	0.948§	0.918–0.969	81.8	97.1	945.2
Beckman-E	0.955	0.927–0.975	92.0	93.0	244.0
Siemens-E	0.966	0.940–0.983	90.9	95.9	326.9

*P=0.0006 vs. Beckman-D; P=0.0027 vs. Siemens-D.

^†P=0.0004 vs. Beckman-D; P=0.0020 vs. Siemens-D.

^‡P=0.0094 vs. Beckman-E; P=0.0014 vs. Siemens-E; P=0.0109 vs. Siemens-D.

^§P=0.0073 vs. Siemens-E.

Abbreviations: UFC, urinary free cortisol; AUC, area under the ROC curve; CI, confidence interval; D, direct assay; E, extraction assay.