TABLE 3.
Specificities of the Elecsys syphilis assay using lots B and C and specificities of comparator assays
| Result by sample type | Elecsys syphilis assay lot B | Elecsys syphilis assay lot C | Architect Syphilis TP assay | LIAISON Treponema screen | Enzygnost syphilis assay |
|---|---|---|---|---|---|
| Routine samples | |||||
| Labor Schottdorf, Germany | |||||
| Total no. tested | 1,000 | 1,000 | 1,000 | ||
| No. confirmed positive | 1 | 1 | 1 | ||
| No. indeterminate | 1b | 1b | 1b | ||
| No. negative | 998 | 998 | 998 | ||
| No. false positive | 1 | 0 | 0 | ||
| Specificity (% [2-sided 95% CI])a | 99.90 (99.44–100.00) | 100.00 (99.63–100.00) | 100.00 (99.63–100.00) | ||
| Blood donor samples | |||||
| Central Institute for Blood Transfusion and Immunology, Austria | |||||
| Total no. tested | 1,049 | 1,049 | 1,049 | ||
| No. confirmed positive | 0 | 0 | 0 | ||
| No. indeterminate | 0 | 0 | 0 | ||
| No. negative | 1,049 | 1,049 | 1,049 | ||
| No. false positive | 0 | 0 | 0 | ||
| Specificity (% [2-sided 95% CI]) | 100.00 (99.65–100.00) | 100.00 (99.65–100.00) | 100.00 (99.65–100.00) | ||
| Ege University, Turkey | |||||
| Total no. tested | 632 | 632 | 632 | ||
| No. confirmed positive | 1 | 1 | 1 | ||
| No. indeterminate | 0 | 0 | 0 | ||
| No. negative | 631 | 631 | 631 | ||
| No. false positive | 3 | 3 | 5 | ||
| Specificity (% [2-sided 95% CI]) | 99.52 (98.62–99.90) | 99.52 (98.62–99.90) | 99.21 (98.16–99.74) | ||
| Overall blood donor specificity (% [2-sided 95% CI]) | 99.82 (99.48–99.96) | 99.82 (99.48–99.96) | 99.21 (98.16–99.74) | 100.00 (99.65–100.00) | |
| Overall specificity (% [2-sided 95% CI]) | 99.85 (99.62–99.96) | 99.89 (99.67–99.98) | 99.21 (98.16–99.74) | 100.00 (99.63–100.00) | 100.00 (99.65–100.00) |
a
CI, confidence interval.
b
Excluded from the specificity calculation due to indeterminate confirmation results.