TABLE 3.
Correlation of increasing signal strength value of four treponemal immunoassays to increasing reactivity with TP-PA or FTA-ABS
| Assay and index valuea | n | No. (%) reactive (n = 1,849) by: |
|
|---|---|---|---|
| TP-PA | FTA-ABS | ||
| BioPlex MBIA | |||
| 0–<1.1 | 1,065 | 12 (1) | 20 (2) |
| 1.1–<3.7 | 100 | 54 (54) | 58 (58) |
| 3.7–<7.9 | 124 | 109 (88) | 110 (89) |
| 7.9–8.0 | 560 | 555 (99) | 551 (98) |
| Z statistic | −39.85 | −39.07 | |
| P | <.0001 | <.0001 | |
| Advia-Centaur CIA | |||
| 0–<1.1 | 1,029 | 1 (<1) | 8 (<1) |
| 1.1–<18.0 | 207 | 129 (62) | 135 (65) |
| 18.0–<44.0 | 194 | 188 (97) | 185 (96) |
| 44.0–45.0 | 419 | 412 (98) | 411 (98) |
| Z statistic | −38.34 | −37.61 | |
| P | <.0001 | <.0001 | |
| Liaison CIA | |||
| 0–<1.10 | 1,047 | 7 (<1) | 19 (2) |
| 1.1–<16.0 | 269 | 192 (71) | 200 (74) |
| 16.0–<60.0 | 304 | 302 (99) | 296 (97) |
| 60.0–70.0 | 229 | 229 (100) | 224 (98) |
| Z statistic | −36.52 | −35.56 | |
| P | <.0001 | <.0001 | |
| Trep-Sure EIA | |||
| 0–<1.3 | 935 | 1 (<1) | 8 (<1) |
| 1.3–<9.0 | 122 | 20 (16) | 25 (20) |
| 9.0–<12.0 | 118 | 89 (75) | 86 (73) |
| 12.0–15.5 | 674 | 620 (92) | 620 (92) |
| Z statistic | −34.04 | −33.60 | |
| P | <.0001 | <.0001 | |
a
P values were determined by Cochran-Armitage test for trend.