Table 3.
Performance of clinical symptoms for diagnosing enteric fever among outpatients with reported fever ≥3 days — Bangladesh, Nepal, and Pakistan, 2016–2019
| Sensitivity (95% CI) | Specificity (95% CI) | PPVa (95% CI) | NPVa (95% CI) | |
|---|---|---|---|---|
| Clinical signs | ||||
| Febrile at presentation, >99.5°F | 59.0% (51.6–65.9) | 55.9% (48.6–63.3) | 13.1% (9.3–18.2) | 92.6% (89.4–95.8) |
| High-grade fever at presentation, ≥103°F | 5.0% (3.5–7.3) | 97.6% (96.4–98.9) | 20.5% (16.5–25.1) | 90.4% (86.5–94.4) |
| Leukopenia | 6.3% (3.3–11.6) | 88.2% (84.4–92.1) | 7.9% (5.0–12.1) | 84.5% (69.2–99.7) |
| Thrombocytopenia | 7.0% (2.8–16.7) | 89.5% (82.3–96.6) | 7.6% (4.1–13.9) | 84.8% (69.1–100.6) |
| Symptoms | ||||
| Absence of cough | 65.5% (55.0–74.7) | 54.7% (43.5–65.9) | 14.2% (10.5–19.0) | 93.5% (90.7–96.3) |
| ≥3 days of being unable to conduct activity | 51.0% (23.8–77.6) | 57.1% (27.3–86.9) | 10.5% (7.6–14.4) | 91.8% (87.4–96.1) |
| Vomiting | 35.2% (23.3–49.2) | 69.8% (54.9–84.8) | 11.3% (7.6–16.5) | 90.5% (86.8–94.2) |
| Headache | 33.4% (11.8–65.3) | 71.8% (43.5–100.1) | 9.1% (6.4–13.0) | 91.7% (86.6–96.7) |
| Abdominal pain | 29.5% (17.3–45.4) | 80.0% (66.9–93.0) | 12.8% (8.6–18.8) | 90.9% (87.5–94.4) |
| Fever duration, ≥7 days | 24.0% (20.1–28.4) | 80.0% (77.5–82.5) | 12.7% (9.3–17.3) | 89.4% (85.6–93.2) |
| Diarrhea | 16.8% (10.4–26.1) | 88.4% (82.8–94.1) | 13.6% (9.8–18.6) | 90.5% (86.8–94.2) |
| Constipation | 4.1% (1.7–9.5) | 94.9% (91.1–98.7) | 8.1% (5.8–11.1) | 89.9% (86.0–93.7) |
| Combined case definition | ||||
| ≥ 3 days of reported fever AND either a) absence of cough OR b) fever at presentation (>99.5 °F) | 88.0% (83.8–91.1) | 30.1% (19.9–40.2) | 12.6% (9.0–17.2) | 95.6% (93.2–98.1) |
| ≥ 3 days of reported fever AND a) Absence of cough OR b) measured fever at presentation (>99.5 °F) OR c) ≥ 3 days of being unable to conduct activity | 94.6% (93.4–95.5) | 13.6% (9.8–17.5) | 10.5% (7.2–15.0) | 97.0% (94.1–100.0) |
| Multiple symptoms: febrile at presentation, absence of cough, ≥3 days of being unable to conduct activity, vomiting, headache, abdominal pain | ||||
| Any 2 of above symptoms | 88.0% (77.5–94.0) | 27.4% (17.3–37.6) | 11.5% (8.0–16.2) | 96.1% (92.8–99.4) |
| Any 3 of above symptoms | 55.5% (37.9–71.8) | 64.2% (46.6–81.8) | 13.5% (9.6–18.7) | 93.5% (89.5–97.5) |
| Any 4 of above symptoms | 23.4% (10.8–43.3) | 87.3% (76.1–98.4) | 14.1% (10.3–18.9) | 91.6% (87.5–95.6) |
Sensitivity, specificity, PPV, and NPV were calculated using mixed-effects logit models with a random effect for study hospital, and were adjusted for age.
Abbreviations: NPV, negative predictive value; PPV, positive predictive value.
aThe PPV and NPV rely on the underlying prevalence of disease. In this population, the prevalence of blood culture–positive enteric fever was 11.6% (2416/20 899), with prevalences of 13.2% (1453/10 990) in Bangladesh, 5.3% (266/5047) in Nepal, and 14.3% (697/4862) in Pakistan.