Table 4. Sensitivity, specificity and predictive values of signs and symptoms for influenza virus positivity among HIV-infected and HIV-uninfected children aged <5 years hospitalised with severe respiratory illness at the Edendale and Klerksdorp hospitals, South Africa, 2011–2015.
| Factors | Influenza positivity | Sensitivity | Specificity | PPV* | NPV** | |
|---|---|---|---|---|---|---|
| Presence of factor n/N (%) |
Absence of factor n/N (%) |
|||||
| Individual clinical signs and symptoms (n = 2 257) | ||||||
| Fever >38°C | 63/821 (8) | 57/1 436 (3) | 53 (43–62) | 64 (62–67) | 8 (6–10) | 96 (94–97) |
| Any fever | 87/1 406 (6) | 33/840 (4) | 73 (63–80) | 38 (36–40) | 6 (5–8) | 96 (95–97) |
| Cough | 114/2 095 (5) | 5/153 (3) | 96 (91–99) | 7 (6–9) | 5 (5–7) | 97 (93–99) |
| Difficulty breathing | 73/1 528 (5) | 46/721 (6) | 61 (52–70) | 32 (28–34) | 5 (4–6) | 94 (92–95) |
| Diarrhoea | 25/332 (8) | 94/1 916 (5) | 21 (14–30) | 86 (84–87) | 8 (5–11) | 95 (94–96) |
| Vomiting | 9/109 (8) | 110/2 139 (5) | 8 (4–14) | 95 (94–96) | 8 (3–15) | 95 (94–96) |
| No feeding | 21/342 (6) | 98/1 907 (5) | 18 (11–26) | 85 (83–86) | 6 (3–8) | 94 (93–96) |
| Lethargy | 49/993 (5) | 70/1 254 (6) | 41 (32–51) | 56 (53–58) | 5 (3–7) | 94 (93–96) |
| Convulsion | 10/81 (12) | 109/2 167 (5) | 8 (4–12) | 97 (96–98) | 12 (6–22) | 95 (94–96) |
| Stridor | 21/580 (4) | 98/1 668 (6) | 18 (11–26) | 74 (71–76) | 4 (2–6) | 94 (93–95) |
| Symptoms duration in days (n = 1 774) | ||||||
| ≤7 days | 14/162 (9) | 100/2 018 (5) | 91 (86–95) | 5 (4–6) | 7 (6–8) | 88 (82–93) |
| ≤10 days | 10/123 (8) | 104/2 057 (5) | 92 (86–96) | 5 (4–6) | 6 (5–7) | 91 (85–96) |
| ≤14 days | 7/87 (8) | 107/2 093 (5) | 92 (84–97) | 5 (4–6) | 4 (3–5) | 94 (88–96) |
| Number of influenza-positive patient (n = 114) | No. cases | Cumulative number | Cumulative % | |||
| ≤7 days | 100 | 100 | 88 | |||
| ≤10 days | 4 | 104 | 91 | |||
| ≤14 days | 3 | 107 | 94 | |||
| 15+ days | 7 | 114 | 100 | |||
*PPV: positive predictive value.
**NPV: negative predictive value.