Table 3 Comparison of the performance* of the Widal test for typhoid fever diagnosis by number of days of fever** prior to admission
Widal titer | Sensitivity (95%CI) | Specificity (95%CI) | Positive Predictive Value | Negative Predictive Value |
|---|---|---|---|---|
≤ 5 days fever (n = 1123) | ||||
TH ≥1:80 | 4/6, 0.67 (0.30-0.90) | 1102/1117, 0.99 (0.98-0.99) | 4/19, 0.21 | 1102/1104, 1.00 |
TH ≥1:160 | 3/6, 0.50 (0.19-0.81) | 1106/1117, 0.99 (0.98-0.99) | 3/14, 0.21 | 1106/1109, 1.00 |
TH ≥1:320 | 2/6, 0.33 (0.10-0.70) | 1110/1117, 0.99 (0.99-1.00) | 2/9, 0.22 | 1110/1114, 1.00 |
TO ≥1:80 | 4/6, 0.67 (0.30-0.90) | 1100/1117, 0.98 (0.98-0.99) | 4/21, 0.19 | 1100/1102, 1.00 |
TO ≥1:160 | 3/6, 0.50 (0.19-0.81) | 1107/1117, 0.99 (0.98-1.00) | 3/13, 0.23 | 1107/1110, 1.00 |
TO ≥1:320 | 1/6, 0.17 (0.03-0.56) | 1112/1117, 1.00 (0.99-1.00) | 1/6, 0.17 | 1112/1117, 1.00 |
> 5 days fever (n = 554) | ||||
TH ≥1:80 | 8/10, 0.80 (0.49-0.94) | 525/544, 0.97 (0.95-0.98) | 8/27, 0.30 | 525/527, 1.00 |
TH ≥1:160 | 8/10, 0.80 (0.49-0.94) | 530/544, 0.97 (0.96-0.98) | 8/22, 0.36 | 530/532, 1.00 |
TH ≥1:320 | 4/10, 0.40 (0.17-0.69) | 533/544, 0.98 (0.96-0.99) | 4/15, 0.27 | 533/539, 0.99 |
TO ≥1:80 | 7/10, 0.70 (0.40-0.89) | 528/544, 0.97 (0.95-0.98) | 7/23, 0.30 | 528/531, 0.99 |
TO ≥1:160 | 7/10, 0.70 (0.40-0.89) | 530/544, 0.97 (0.96-0.98) | 7/21, 0.33 | 530/533, 0.99 |
TO ≥1:320 | 5/10, 0.50 (0.24-0.76) | 537/544, 0.99 (0.97-0.99) | 5/12, 0.42 | 537/542, 0.99 |