| Covariate | Adjusted OR# (95% CI) | p-value |
| Asthma | 0.62 (0.36–1.05) | 0.075 |
| Triage criteria¶ | ||
| A: severe respiratory distress | 1.41 (0.64–3.13) | 0.395 |
| B: increased respiratory rate | 2.05 (1.35–3.09) | 0.001 |
| C: oxygen saturation ≤ 92% | 3.05 (1.46–6.35) | 0.003 |
| D: respiratory exhaustion | 5.57 (1.76–17.57) | 0.003 |
| E: severe clinical dehydration or clinical shock | 4.57 (2.78–7.52) | <0.001 |
| F: altered consciousness | 5.92 (3.31–10.57) | <0.001 |
| Dyspnoea | 0.83 (0.38–1.79) | 0.633 |
| Admission ≤4 days after symptom onset | 0.60 (0.38–0.94) | 0.025 |
| Pre-admission inhaled corticosteroids | 0.34 (0.18–0.66) | 0.001 |
| Required supplemental oxygen on admission | 2.08 (1.03–4.19) | 0.041 |
| In-hospital antibiotics | 4.22 (1.03–17.24) | 0.045 |
| In-hospital oral/i.v. corticosteroids | 1.31 (0.80–2.14) | 0.275 |
#: adjusted for all other covariates in the model; ¶: National Health Service Swine Flu Community Assessment Tool criteria [8].