Clinical characteristics of patients with H1N1 influenza-related pneumonia compared with community-acquired pneumonia (CAP)
| Characteristic | H1N1 cohort (n=254) | CAP cohort (n=648) | p Value |
| Demographics | |||
| Age (years) | 42 (29–54) | 75 (61–84) | <0.001 |
| Male | 109 (42.9%) | 367 (56.6%) | <0.001 |
| Admission observations | |||
| Temperature (°C), mean (95% CI) | 38.1 (37.9 to 38.2) (n=245) | 37.5 (37.4 to 37.6) (n=644) | <0.001 |
| Pulse (/min) | 110 (97–120) (n=244) | 100 (86–115) (n=646) | <0.001 |
| SBP (mm Hg), mean (95% CI) | 125 (123 to 128) (n=243) | 126 (124 to 129) (n=646) | 0.61 |
| Respiratory rate (/min) | 24 (19–28) (n=240) | 22 (18–28) (n=646) | 0.14 |
| Confusion | 18 (7.1%) | 182 (28.1%) | <0.001 |
| Outcome | |||
| Critical care admission | 88 (34.6%) | 83 (12.8%) | <0.001 |
| LOS for survivors (days) | 6 (3–11) (n=206) | 8 (4–14) (n=553) | 0.003 |
| Inpatient death | 29 (11.4%) | 91 (14.0%) | 0.296 |
| Investigations | |||
| Bilateral consolidation | 89 (39.0% of 228) | 129 (19.9%) | <0.001 |
| White cell count (×109/l) | 7.6 (5.4–11.3) (n=239) | 14.5 (10.5–19.9) (n=646) | <0.001 |
| Urea (mmol/l) | 4.7 (3.3–6.9) (n=232) | 7.9 (5.5–12.6) (n=647) | <0.001 |
| C-reactive protein (mg/l) | 85 (34–199) (n=184) | 148 (61–248) (n=602) | <0.001 |
| Albumin (g/dl) | 34 (30–40) (n=177) | 31 (27–35) (n=488) | <0.001 |
| Symptoms | |||
| Productive cough | 147 (57.9%) | 287 (58.7% of 489*) | 0.83 |
| Dyspnoea | 151 (59.4%) | 428 (87.5% of 489*) | <0.001 |
| Comorbidity | |||
| Asthma | 64 (25.2%) | 57 (8.8%) | <0.001 |
| COPD | 24 (9.4%) | 169 (26.1%) | <0.001 |
| CCF | 1 (0.4%) | 46 (7.1%) | <0.001 |
| Diabetes mellitus | 25 (9.8%) | 100 (15.4%) | 0.029 |
| Charlson index, mean (95% CI) | 1.11 (0.94 to 1.27) | 1.33 (1.23 to 1.44) | 0.023 |
Values are median (IQR) or n (%) of patients unless otherwise stated. Normally distributed data are reported as means with 95% CI and non-normally distributed data as medians with interquartile range.
↵* Data not given for patients with confusion.
CAP, community-acquired pneumonia; COPD, chronic obstructive pulmonary disease; CCF, congestive cardiac failure; LOS, length of hospital stay; SBP, systolic blood pressure.