Performance of Clinical Prediction Rules and Simple Heuristics for the Diagnosis of Influenza
| Derivation group | Validation group | All patients | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Flu/Total (%) | LR | In Group (%) | Flu/Total (%) | LR | In Group (%) | Flu/Total (%, 95% CI) | LR | In Group (%) | |
| Flu score 1 | |||||||||
| Low risk (0–11) | 7/86 (8.1) | 0.17 | 26.4 | 1/34 (2.9) | 0.06 | 25.6 | 8/120 (6.7, 3.4–12.6) | 0.14 | 26.1 |
| Moderate risk (12–15) | 24/106 (22.6) | 0.57 | 32.5 | 16/46 (34.8) | 0.98 | 34.6 | 40/152 (26.3, 20.0–33.8) | 0.69 | 33.1 |
| High risk (16–24) | 79/134 (59.0) | 2.82 | 41.1 | 30/53 (56.6) | 2.39 | 39.8 | 109/187 (58.3, 51.1–65.1) | 2.69 | 40.7 |
| Flu score 2 | |||||||||
| Low risk (0–2) | 6/77 (7.8) | 0.17 | 23.6 | 1/32 (3.1) | 0.06 | 24.1 | 7/109 (6.4, 3.1–12.7) | 0.13 | 23.7 |
| Moderate risk (4–6) | 44/149 (29.5) | 0.82 | 45.7 | 16/56 (28.6) | 0.73 | 42.1 | 60/205 (29.3, 23.5–35.8) | 0.80 | 44.7 |
| High risk (8–12) | 60/100 (60.0) | 2.95 | 30.7 | 30/45 (66.7) | 3.66 | 33.8 | 90/145 (62.1, 54.0–69.6) | 3.15 | 31.6 |
| Flu score 3 | |||||||||
| Low risk (0–2) | 10/109 (9.2) | 0.20 | 33.4 | 2/40 (5.0) | 0.10 | 30.1 | 12/149 (8.1, 4.7–13.5) | 0.17 | 32.5 |
| Moderate risk (3) | 25/90 (27.8) | 0.76 | 27.6 | 14/39 (35.9) | 1.02 | 29.3 | 39/129 (30.2, 23.0–38.6) | 0.83 | 28.1 |
| High risk (4–6) | 75/127 (59.1) | 2.83 | 39.0 | 31/54 (57.4) | 2.47 | 40.6 | 106/181 (58.6, 51.3–65.5) | 2.72 | 39.4 |
| Flu score 4 | |||||||||
| Low risk (−1–3) | 4/36 (11.1) | 0.25 | 11.1 | 1/19 (5.3) | 0.10 | 14.3 | 5/55 (9.1, 4.0–19.6) | 0.19 | 12.0 |
| Moderate risk (4–8) | 36/166 (21.7) | 0.55 | 51.2 | 17/65 (26.2) | 0.65 | 48.9 | 53/231 (22.9, 18.0–28.8) | 0.57 | 50.5 |
| High risk (9–11) | 69/122 (56.6) | 2.57 | 37.7 | 29/49 (59.2) | 2.65 | 36.8 | 98/171 (57.1, 49.8–64.5) | 2.59 | 37.4 |
| Flu score 5 | |||||||||
| Low risk (0–11) | 3/28 (10.7) | 0.24 | 8.6 | 0/17 (0.0) | 0.0 | 12.8 | 3/45 (6.7, 2.3–17.9) | 0.14 | 9.8 |
| Moderate risk (12–16) | 59/220 (26.8) | 0.72 | 67.9 | 26/84 (31.0) | 0.82 | 63.2 | 85/304 (28.0, 23.2–33.3) | 0.75 | 66.5 |
| High risk (17+) | 47/76 (61.8) | 3.20 | 23.5 | 21/32 (65.6) | 4.27 | 24.1 | 68/108 (63.0, 53.6–71.5) | 3.28 | 23.6 |
| Heuristics | |||||||||
| Fever, cough | |||||||||
| Positive (both present) | NA | NA | 96/157 (61.1, 53.4–68.4) | 3.03 | 34.2 | ||||
| Negative (0 or 1 present) | NA | NA | 61/302 (20.2, 16.1–25.1) | 0.49 | 65.8 | ||||
| Fever, cough, and acute-onset | |||||||||
| Positive (all 3 present) | NA | NA | 64/86 (74.4, 64.3–82.5) | 5.59 | 18.7 | ||||
| Negative (0, 1, or 2 present) | NA | NA | 93/373 (24.9, 20.8–29.6) | 0.64 | 81.3 | ||||