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


*Group 1 were those with S. typhi isolated from blood culture (n = 16), group 2 were those with non-typhi serotypes of S. enterica (NTS) isolated from blood culture (n = 49), group 3 were those with pathogenic bacteria other than Salmonellae isolated from blood culture (n = 113), and group 4 were those whose blood culture yielded no bacterial pathogen (n = 1502).

Ley et al. BMC Infectious Diseases 2010 10:180   doi:10.1186/1471-2334-10-180

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