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Table 3 Comparison of the performance* of the Widal test for typhoid fever diagnosis by number of days of fever** prior to admission

From: Evaluation of the Widal tube agglutination test for the diagnosis of typhoid fever among children admitted to a rural hdospital in Tanzania and a comparison with previous studies

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
  1. *The values were calculated using culture-confirmed typhoid fever cases (group 1; n = 16) as the true positives and those cases from which S. typhi were not isolated from blood culture (groups 2, 3, and 4; n = 1664) as the true negatives. **Three patients whose fever duration was unknown were excluded from the analysis.