The diagnostic values of non-treponemal titres before treatment for CS stratified by three treatment groups
| Group | AUC (95% CI) | cut-off | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | Youden’s index |
| Group 1a | 0.67 (0.45 to 0.90) | 1:32 | 44.4 (12.0 to 76.9) | 92.3 (90.8 to 93.8) | 4.2 (0.2 to 8.2) | 99.5 (99.1 to 99.9) | 0.35 |
| Group 1b | 0.87 (0.82 to 0.93) | 1:16 | 100.0 (100.0 to 100.0) | 81.9 (75.9 to 87.8) | 9.4 (0 to 19.5) | 100.0 (100.0 to 100.0) | 0.73 |
| Group 2 | 0.79 (0.70 to 0.87) | 1:8 | 81.5 (66.8 to 96.1) | 78.5 (72.3 to 84.6) | 37.3 (24.9 to 49.6) | 96.4 (93.4 to 99.5) | 0.60 |
Group 1a: women treated before 28 weeks.
Group 1b: women treated after 28 weeks.
Group 2: women untreated.
AUC, area under the curve; CS, congenital syphilis; NPV, negative predicted value; PPV, positive predicted value.