Table 3

Syndromic diagnosis and laboratory-confirmed STIs

Syndromic diagnosisAny STI, n (%)* Chlamydia trachomatis, n (%)* Neisseria gonorrhoeae, n (%)* Trichomonas vaginalis, n (%)*
YesNoPerformance (95% CI)YesNoPerformance (95% CI)YesNoPerformance (95% CI)YesNoPerformance (95% CI)
Antenatal clinics (n=765)
LAPS
(166/765; 21.7%)
Yes60 (18.4)106 (14.2)Sens: 18% (14% to 23%)
Spec: 76% (72% to 80%)
PPV: 36% (29% to 44%)
NPV: 55% (51% to 59%)
30 (17.1)136 (23.0)Sens: 17% (12% to 24%)
Spec: 77% (73% to 80%)
PPV: 18% (13% to 25%)
NPV: 76% (72% to 79%)
15 (13.8)151 (23.0)Sens: 14% (8% to 22%)
Spec: 77% (74% to 80%)
PPV: 9% (5% to 14%)
NPV: 84% (81% to 87%)
29 (83.0)457 (77.0)Sens: 17% (12% to 23%)
Spec: 77% (73% to 80%)
PPV: 17% (12% to 24%)
NPV: 76% (73% to 80%)
No267 (81.7)332 (75.8)145 (82.9)454 (77.0)94 (86.2)505 (77.0)142 (83.0)457 (77.0)
VDS
(156/765; 20.4%)
Yes60 (18.4)96 (22.0)Sens: 18% (14% to 23%)
Spec: 78% (74% to 82%)
PPV: 38% (40% to 47%)
NPV: 56% (52% to 60%)
37 (21.1)119 (20.2)Sens: 21% (15% to 28%)
Spec: 80% (76% to 83%)
PPV: 24% (17% to 31%)
NPV: 77% (74% to 81%)
16 (14.7)140 (21.3)Sens: 15% (9% to 23%)
Spec: 79% (75% to 82%)
PPV: 10% (96% to 16%)
NPV: 85% (82% to 87%)
33 (19.3)123 (20.7)Sens: 19% (14% to 26%)
Spec: 79% (76% to 82%)
PPV: 21% (15% to 28%)
NPV: 77% (74% to 81%)
No267 (81.7)342 (78.1)138 (78.9)471 (79.8)93 (85.3)516 (78.7)138 (80.7)471 (79.3)
Well woman clinics (n=614)
LAPS (200/614; 32.6%)Yes46 (29.9)154 (33.5)Sens: 30% (23% to 38%)
Spec: 67% (62% to 71%)
PPV: 23% (17% to 29%)
NPV: 74% (69% to 78%)
19 (41.3)181 (31.9)Sens: 41% (27% to 57%)
Spec: 68% (64% to 72%)
PPV: 10% (6% to 14%)
NPV: 93% (91% to 96%)
15 (30.6)185 (32.7)Sens: 31% (18% to 45%)
Spec: 67% (63% to 71%)
PPV: 8% (4% to 12%)
NPV: 92% (89% to 94%)
24 (26.1)176 (33.7)Sens: 26% (17% to 36%)
Spec: 66% (62% to 70%)
PPV: 12% (8% to 17%)
NPV: 84% (80% to 87%)
No108 (70.1)306 (66.5)27 (58.8)387 (68.1)34 (69.4)380 (67.3)68 (73.9)346 (66.3)
VDS
(422/614; 68.7%)
Yes114 (74.0)308 (67.0)Sens: 74% (66% to 81%)
Spec: 33% (29% to 38%)
PPV: 25% (22% to 29%)
NPV: 79% (74% to 84%)
33 (71.7)389 (68.5)Sens: 72% (57% to 84%)
Spec: 32% (28% to 36%)
PPV: 8% (6% to 9%)
NPV: 93% (90% to 96%)
37 (75.5)385 (68.1)Sens: 75% (61% to 87%)
Spec: 32% (28% to 36%)
PPV: 9% (7% to 10%)
NPV: 94% (90% to 96%)
70 (76.1)352 (67.4)Sens: 76% (66% to 84%)
Spec: 33% (28% to 37%)
PPV: 17% (15% to 18%)
NPV: 89% (84% to 92%)
No40 (26.0)152 (33.0)13 (28.3)179 (31.5)12 (24.5)180 (31.9)22 (23.9)170
(32.6)
Sexual health clinics (n=385)
LAPS
(282/385; 73.2%)
Yes109 (75.1)173 (72.1)Sens: 75% (67% to 82%)
Spec: 28% (22% to 34%)
PPV: 39% (33% to 45%)
NPV: 65% (55% to 74%)
62 (79.5)220 (71.7)Sens: 79% (69% to 88%)
Spec: 28% (23% to 34%)
PPV: 22% (20% to 24%)
NPV: 84% (77% to 90%)
46 (27.0)236 (73.3)Sens: 73% (60% to 83%)
Spec: 27% (22% to 32%)
PPV: 16% (12% to 21%)
NPV: 84% (75% to 90%)
40 (74.1)242 (73.1)Sens: 74% (60% to 85%)
Spec: 27% (22% to 32%)
PPV: 14% (11% to 18%)
NPV: 86% (78% to 92%)
No36 (24.8)67 (27.9)16 (20.5)87 (28.3)17 (27.0)86 (26.7)14 (25.9)89 (26.9)
VDS
(281/385; 73.0%)
Yes106 (73.1)175 (72.9)Sens: 73% (65% to 80%)
Spec: 27% (22% to 33%)
PPV: 38% (35% to 41%)
NPV: 62% (54% to 70%)
61 (78.2)220 (71.7)Sens: 78% (67% to 87%)
Spec: 28% (23% to 34%)
PPV: 22% (19% to 24%)
NPV: 84% (76% to 89%)
42 (66.7)239 (74.2)Sens: 67% (54% to 78%)
Spec: 26% (21% to 31%)
PPV: 15% (13% to 17%)
NPV: 80% (73% to 85%)
40 (74.1)241 (72.8)Sens: 74% (60% to 85%)
Spec: 27% (22% to 32%)
PPV: 14% (12% to 16%)
NPV: 86% (80% to 91%)
No39 (26.9)65 (27.1)17 (21.8)87 (28.3)21 (33.3)83 (25.8)14 (25.9)90 (27.2)
  • *Prevalence of any and individual STIs in this population.

  • LAPS, lower abdominal pain syndrome; NPV, negative predictive value; PPV, positive predictive value; Sens, sensitivity; Spec, specificity; STI, sexually transmitted infection; VDS, vaginal discharge syndrome.