TABLE 2.

Specificities of the Elecsys syphilis assay using lot A and specificities of comparator assays

Result by sample type	Elecsys syphilis assay lot A	Architect syphilis TP assay	LIAISON Treponema screen	Serodia-TPPA	Vitros syphilis TPA	Enzygnost syphilis assay	Immulite 2000 syphilis screen
Routine samples
Total no. tested	3,500	1,500	3,500	1,500			2,000
No. confirmed positive	14	1	14	1			13
No. indeterminate	0	0	0	0			0
No. negative	3,486	1,499	3,486	1,499			1,987
No. false positive	7	5	12	2			0
Specificity (% [2-sided 95% CI])a	99.80 (99.59–99.92)	99.67 (99.22–99.89)	99.66 (99.40–99.82)	99.87 (99.52–99.98)			100.00 (99.81–100.00)
Blood donor samples
Total no. tested	4,579	3,006			1,574	1,506	1,574
No. confirmed positive	0	0			0	0	0
No. indeterminate	2b	2b			0	1b	0
No. negative	4,577	3,004			1,574	1,505	1,574
No. false positive	3	8			0	3	0
Specificity (% [2-sided 95% CI])	99.93 (99.81–99.99)	99.73 (99.48–99.88)			100.00 (99.77–100.00)	99.80 (99.42–99.46)	100.00 (99.77–100.00)
Total samples
Total no. tested	8,079	4,506	3,500	1,500	1,574	1,506	3,574
No. confirmed positive	14	1	14	1	0	0	13
No. indeterminate	2b	2b	0	0	0	1b	0
No. negative	8,063	4,503	3,486	1,499	1,574	1,505	3,561
No. false positive	10	13	12	2	0	3	0
Specificity (% [2-sided 95% CI])	99.88 (99.77–99.94)	99.71 (99.51–99.85)	99.66 (99.40–99.82)	99.87 (99.52–99.98)	100.00 (99.77–100.00)	99.80 (99.42–99.96)	100.00 (99.90–100.00)

^aCI, confidence interval.

^bExcluded from the specificity calculation due to indeterminate confirmation results.