Table 4

Diagnostic strategies to identify infection with Chlamydia trachomatis and/or Neisseria gonorrhoeae in 703 antenatal care attendees in Botswana.

Positive on assessment

Cervical infection

Sensitivity

Specificity

LR+*

LR-

PPV

NPV

n

(%)

N

(%)

Symptoms and signs

VDS algorithm

104

(15)

11

(11)

0.16

0.85

1.12 (0.63–1.92)

0.98

0.11

0.91

Symptoms alone: VD and/or LAP

155

(22)

14

(9)

0.21

0.78

0.94 (0.57–1.49)

1.02

0.09

0.90

Signs alone: VD (excl. candidiasis)

227

(32)

30

(13)

0.45

0.69

1.45 (1.06–1.89)

0.78

0.13

0.92

Risk scores†, sensitivity minimum 0.7

Sociodemographic risk score

327

(47)

50

(15)

0.75

0.56

1.71 (1.42–1.99)

0.45

0.15

0.96

Clinical risk score

372

(53)

54

(15)

0.81

0.50

1.61 (1.37–1.83)

0.39

0.15

0.96

Microscopy risk score

273

(39)

51

(19)

0.76

0.65

2.18 (1.80–2.55)

0.37

0.19

0.96

Risk scores, sensitivity minimum 0.4

Sociodemographic risk score

156

(22)

29

(19)

0.43

0.80

2.17 (1.55–2.91)

0.71

0.19

0.93

Clinical risk score

117

(17)

29

(25)

0.43

0.86

3.13 (2.20–4.30)

0.66

0.25

0.94

Microscopy risk score

116

(17)

29

(25)

0.43

0.86

3.16 (2.22–4.34)

0.66

0.25

0.94

LR+ = positive likelihood ratio; LR- = negative likelihood ratio; PPV = positive predictive value; NPV = negative predictive value; VDS = vaginal discharge syndrome;

LAP = lower abdominal pain; VD = vaginal discharge

* The positive likelihood ratios are calculated with 95% confidence interval.

†Risk factors included in each risk score are described in Table 1

Romoren et al. BMC Infectious Diseases 2007 7:27   doi:10.1186/1471-2334-7-27