Table 4 Secondary analysis of the performance of a Widal anti-TH and -TO titer of ≥1:80 for typhoid fever diagnosis using group 1 as true positives and three different control groups as true negatives*
| Control group | Sensitivity (95%CI) | Specificity (95%CI) | Positive Predictive Value | Negative Predictive Value |
|---|---|---|---|---|
| TH titer ≥1:80: | ||||
| Groups 2, 3, and 4 (n = 1664) |
12/16, 0.75 (0.51-0.90) |
1630/1664, 0.98 (0.97-0.99) | 12/46, 0.26 |
1630/1634, 1.00 |
| Groups 2 and 3 (n = 162) |
12/16, 0.75 (0.51-0.90) |
154/162, 0.95 (0.91-0.97) | 12/20, 0.60 | 154/158, 0.97 |
| Group 3 (n = 113) |
12/16, 0.75 (0.51-0.90) |
112/113, 0.99 (0.95-1.00) | 12/13, 0.92 | 112/116, 0.97 |
| TO titer ≥1:80: | ||||
| Groups 2, 3, and 4 (n = 1664) |
11/16, 0.69 (0.44-0.86) |
1631/1664, 0.98 (0.97-0.99) | 11/44, 0.25 |
1631/1636, 1.00 |
| Groups 2 and 3 (n = 162) |
11/16, 0.69 (0.44-0.86) |
155/162, 0.96 (0.91-0.98) | 11/18, 0.61 | 155/160, 0.97 |
| Group 3 (n = 113) |
11/16, 0.69 (0.44-0.86) |
113/113, 1.00 (0.97-1.00) | 11/11, 1.00 | 113/118, 0.96 |