Table 1.
Bioplex syphilis IgG performance based on user-defined cutoff values in different patient cohortsa
| Patient cohort | AI cutoff | No. of specimens with indicated Bioplex result/TP-PA result |
Sensitivity (%) | Specificity (%) | ROC AUC (SE) | |||
|---|---|---|---|---|---|---|---|---|
| +/+ | −b/− | −/+ | +/− | |||||
| RPR nonreactive | ||||||||
| Incarcerated | ≥6 | 33 | 23 | 24 | 2 | 33/57 (57.9) | 23/25 (92) | 0.832 (0.047) |
| ≥8 | 29 | 24 | 28 | 1 | 29/57 (50.9) | 24/25 (96) | ||
| Women attending OB/Gyn clinics | ≥6 | 11 | 21 | 10 | 2 | 11/21 (52.4) | 21/23 (91.3) | 0.956 (0.035) |
| ≥8 | 11 | 23 | 10 | 0 | 11/21 (52.4) | 23/23 (100) | ||
| Women at delivery | ≥6 | 1 | 9 | 5 | 0 | 1/6 (16.7%) | 9/9 (100) | 0.763 (0.134) |
| ≥8 | 1 | 9 | 5 | 0 | 1/6 (16.7%) | 9/9 (100) | ||
| RPR titer = 1:1 | ||||||||
| Incarcerated | ≥6 | 17 | 2 | 5 | 2 | 17/22 (77.3) | 2/4 (50) | 0.803 (0.083) |
| ≥8 | 17 | 3 | 5 | 1 | 17/22 (77.3) | 3/4 (75) | ||
| Women attending OB/Gyn clinics | ≥6 | 3 | 5 | 2 | 1 | 3/5 (60) | 5/6 (83.3) | 0.894 (0.098) |
| ≥8 | 2 | 6 | 3 | 0 | 2/5 (40) | 6/6 (100) | ||
| Women at delivery | ≥6 | 3 | 2 | 2 | 0 | 3/5 (60) | 2/2 (100) | 0.915 (0.11) |
| ≥8 | 3 | 2 | 2 | 0 | 3/5 (60) | 2/2 (100) | ||
| RPR titer ≥ 1:2 | ||||||||
| Incarcerated | ≥6 | 106 | 2 | 3 | 0 | 106/109 (97.2) | 2/2 (100) | 0.986 (0.011) |
| ≥8 | 103 | 2 | 6 | 0 | 103/109 (94.5) | 2/2 (100) | ||
| Women attending OB/Gyn clinics | ≥6 | 30 | 0 | 1 | 0 | 30/31 (96.8) | N/A | N/A |
| ≥8 | 30 | 0 | 1 | 0 | 30/31 (96.8) | N/A | ||
| Women at delivery | ≥6 | 7 | 0 | 0 | 0 | 7/7 (100) | N/A | N/A |
| ≥8 | 7 | 0 | 0 | 0 | 7/7 (100) | N/A | ||
a
Data represent all specimens reactive by Bioplex 2200 syphilis IgG assay (antibody index ≥ 1.1). RPR, rapid plasma reagin; AI, Bioplex IgG antibody index; TP-PA, Treponema pallidum particle agglutination; ROC AUC, receiver operating characteristic area under the curve; N/A, not applicable.
b
−, nonreactive or inconclusive.