Factors associated with virus only detection compared to no pathogens detected by univariate and multivariate analysis
| Variable | Virus only detected/ virus only detected + no pathogen detected | Baseline model# | p-value | Multivariate model¶ | p-value |
| C-reactive protein mg·L−1 | |||||
| Total | 69/198 | ||||
| <10 | 13/85 (15) | 1 | <0.001 | 1 | <0.001 |
| 10–50 | 36/71 (51) | 5.6 (2.7–12.0) | 4.6 (2.0–10.4) | ||
| 51–100 | 13/24 (54) | 6.7 (2.5–18.3) | 3.5 (1.1–11.4) | ||
| >100 | 7/18 (39) | 3.7 (1.2–11.7) | 2.7 (0.7–10.3) | ||
| Temperature °C+ | |||||
| Total | 66/192 | ||||
| <37.0 | 31/123 (25) | 1 | <0.001 | 1 | 0.004 |
| 37.0–37.5 | 16/43 (37) | 1.7 (0.8–3.7) | 1.2 (0.5–2.7) | ||
| >37.5 | 19/26 (73) | 8.0 (3.1–20.9) | 5.3 (1.8–15.6) | ||
| Age years | |||||
| Total | 69/198 | ||||
| ≤65 | 25/66 (38) | 1 | 0.75 | 1 | 0.98 |
| 66–80 | 34/103 (33) | 0.8 (0.4–1.5) | 1.0 (0.5–2.2) | ||
| >80 | 10/29 (34) | 0.9 (0.3–2.2) | 1.0 (0.3–3.0) | ||
| Sex | |||||
| Total | 69/198 | ||||
| Male | 35/96 (35) | 1 | 0.65 | NA | |
| Female | 34/102 (34) | 1.1 (0.6–2.1) | NA | ||
| Antibiotics prior to admission | |||||
| Total | 69/198 | ||||
| No | 44/140 (31) | 1 | 0.14 | 1 | 0.11 |
| Yes | 25/58 (43) | 1.6 (0.9–3.0) | 1.8 (0.8–3.8) | ||
| Duration of illness days | |||||
| Total | 69/198 | ||||
| >5 | 22/69 (32) | 1 | 0.03 | 1 | 0.16 |
| 3–5 | 34/74 (46) | 1.8 (0.9–3.6) | 1.7 (0.8–3.9) | ||
| ≤2 | 13/55 (24) | 0.7 (0.3–1.5) | 0.8 (0.3–2.0) | ||
| Diabetes mellitus | |||||
| Total | 67/195 | ||||
| No | 54/168 (32) | 1 | 0.1 | NA | |
| Yes | 13/27 (48) | 2.0 (0.9–4.9) | NA | ||
| Cardiovascular disease | |||||
| Total | 67/195 | ||||
| No | 26/87 (30) | 1 | 0.18 | NA | |
| Yes | 41/108 (38) | 1.5 (0.8–2.9) | NA | ||
| Current smoker | |||||
| Total | 69/197 | ||||
| No | 47/124 (38) | 1 | 0.23 | NA | |
| Yes | 22/73 (30) | 0.7 (0.4–1.3) | NA | ||
| Influenza vaccination | |||||
| Total | 67/193 | ||||
| Yes | 50/145 (35) | 1 | 0.97 | NA | |
| No | 17/48 (35) | 1.0 (0.5–2.0) | NA |
Data are presented as n/N (%) or adjusted OR (95% CI), unless otherwise stated. Bold indicates statistical significance. NA: not included. #: adjusted for age; ¶: adjusted for C-reactive protein and temperature on admission, age, antibiotic use prior to admission and duration of illness prior to admission; +: also associated with viral detection rate as a linear trend (p<0.001).