Test characteristics of clinical signs and symptoms for diagnosing influenza*
| Test | Number of studies (n) | Positive likelihood ratio | Negative likelihood ratio | Diagnostic odds ratio (CI)† |
|---|---|---|---|---|
| *CI defined in glossary. | ||||
| †Calculated as the odds of the symptom or finding among patients with the disease compared with the odds of the symptom or finding among those not having the disease. | ||||
| ‡Not significant. | ||||
| Fever (37.8–38.5°C) | 3 | 1.8 | 0.40 | 4.5 (1.8 to 11.0) |
| Feverish (patient report) | 2 | Not reported | Not reported | 1.1 (0.88 to 1.4)‡ |
| Cough | 4 | 1.1 | 0.42 | 2.8 (2.1 to 3.7) |
| Myalgia | 3 | 0.93 | 1.2 | 0.79 (0.54 to 1.1)‡ |
| Headache | 4 | 1.0 | 0.75 | 1.4 (1.2 to 1.8) |
| Sore throat | 3 | 1.0 | 0.96 | 1.1 (0.87 to 1.3)‡ |
| Sneezing | 2 | 1.2 | 0.87 | 1.3 (0.95 to 1.9)‡ |
| Nasal congestion | 2 | 1.1 | 0.49 | 2.3 (1.9 to 2.8) |