Table 2.
Presence of context, signs and symptoms in influenza positive and negative subjects and corresponding crudea and adjusted odds ratios (95%CI)b.
| Contexts. signs and symptoms | Influenza pos (n = 2409) |
Influenza neg (n = 2175) |
Crude OR (95%CI) |
Adjusted OR (95%CI) |
|---|---|---|---|---|
| Body temperature >37.8°C. No. (%) | 2271 (94.3) | 1902 (87.5) | 2.36 (1.91 to 2.92) | 2.13 (1.58 to 2.68)c |
| Sudden onset. No. (%) | 2154 (89.4) | 1874 (86.2) | 1.36 (1.14 to 1.62) | 1.25 (0.99 to 1.51) |
| Influenza epidemic. No. (%) | 2066 (85.8) | 1146 (52.7) | 5.41 (4.69 to 6.23) | 6.28 (5.03 to 7.54)c |
| Cough. No. (%) | 2060 (85.5) | 1425 (65.5) | 3.11 (2.69 to 3.59) | 2.59 (2.14 to 3.04)c |
| Shivering. No. (%) | 1999 (83.0) | 1706 (78.4) | 1.34 (1.16 to 1.55) | 1.13 (0.92 to 1.33) |
| Weakness. No. (%) | 1965 (81.6) | 1691 (77.7) | 1.27 (1.10 to 1.46) | 1.03 (0.84 to 1.21) |
| Headache. No. (%) | 1918 (79.6) | 1590 (73.1) | 1.44 (1.25 to 1.65) | 1.16 (0.96 to 1.37) |
| Muscle pain. No. (%) | 1838 (76.3) | 1567 (72.0) | 1.25 (1.09 to 1.43) | 1.16 (0.97 to 1.36) |
| Nose symptoms. No. (%) | 1620 (67.2) | 1208 (55.5) | 1.64 (1.46 to 1.85) | 1.38 (1.18 to 1.58) |
| Red throat. No. (%) | 1529 (63.5) | 1333 (61.3) | 1.10 (0.97 to 1.24) | 0.95 (0.81 to 1.09) |
| Lack of appetite. No. (%) | 1453 (60.3) | 1130 (52.0) | 1.41 (1.25 to 1.58) | 1.15 (0.98 to 1.32) |
| RSV epidemic. No. (%) | 1026 (42.6) | 1010 (46.4) | 0.86 (0.76 to 0.96) | 1.14 (0.99 to 1.29) |
| ILI contacts in the family. school or workplace. No. (%) | 928 (38.5) | 562 (25.8) | 1.80 (1.59 to 2.04) | Not in model |
| ILI contacts pre/post an epidemic. No. (%). n = 1372 | 134 (39.1) | 180 (17.5) | 3.02 (2.31 to 3.96) | 3.14 (2.23 to 4.05)c |
| ILI contacts during an epidemic. No. (%)c. n = 3212 | 79'4 (38.4) | 382 (33.3) | 1.25 (1.07 to 1.45) | 1.24 (1.03 to 1.44) |
| Expectoration. No. (%) | 661 (27.4) | 456 (21.0) | 1.43 (1.24 to 1.63) | Not in model |
| Expectoration on illness day 0. No. (%). n = 117 | 9 (18.37) | 15 (22.06) | 0.80 (0.32 to 2.00) | 2.24 (0.93 to 3.55) |
| Expectoration on illness day 1. No. (%). n = 2101 | 269 (25.33) | 165 (15.88) | 1.80 (1.45 to 2.23) | 1.36 (1.06 to 1.66)c |
| Expectoration on illness day 2. No. (%). n = 1676 | 262 (27.61) | 159 (21.87) | 1.35 (1.09 to 1.71) | 1.00 (0.83 to 1.17) |
| Eye symptoms. No. (%) | 659 (27.4) | 481 (22.1) | 1.33 (1.16 to 1.52) | 1.08 (0.90 to 1.27) |
| Gastro-intestinal symptoms. No. (%) | 368 (15.3) | 374 (17.2) | 0.87 (0.74 to 1.02) | 0.84 (0.68 to 1.00) |
| Ear symptoms. No. (%) | 355 (14.7) | 304 (14.0) | 1.06 (0.90 to 1.26) | 0.88 (0.71 to 1.05) |
| Dyspnoe. No. (%) | 236 (9.8) | 186 (8.6) | 1.16 (0.95 to 1.42) | 1.18 (0.90 to 1.45) |
| Dizziness. No. (%) | 233 (9.7) | 177 (8.1) | 1.21 (0.99 to 1.48) | 1.18 (0.87 to 1.48) |
| Vaccination against influenza. No. (%) | 198 (8.2) | 267 (12.3) | 0.64 (0.53 to 0.78) | 0.67 (0.50 to 0.85) |
| Ronchi. No. (%) | 166 (6.9) | 136 (6.3) | 1.11 (0.88 to 1.40) | 0.93 (0.65 to 1.20) |
| Confusion. No. (%) | 22 (0.9) | 22 (1.0) | 0.90 (0.50 to 1.63) | not in model |
| Age difference of 10 years | NA | NA | NA | 0.97 (0.94 to 1.01) |
| Age. mean (SE) c | 28.90 (0.39) | 31.27 (0.41) | NA | Not in model |
| Temp. mean (SE) c | 38.70 (0.01) | 38.46 (0.02) | NA | Not in model |
NA = not applicable CI = confidence interval
a Crude Odds ratios were estimated using Chi2
b Adjusted odds ratios were estimated using Generalized Estimating Equations. 95%CI were calculated by bootstrap after multiple imputation.
c significant different: p-value < 0.0001