Table 1.
Demographic and clinical characteristics of patients with influenza A H1N1 pneumonia.
| Characteristics | No bacterial co-infection (N = 86) | Bacterial co-infection (N = 42) | p-value |
|---|---|---|---|
| Age (years), mean ± SD | 44 ± 16 | 44 ± 19 | 0.98 |
| Sex (male), n (%) | 45 (53) | 23 (55) | 0.79 |
| Current smoking, n (%) | 16 (19) | 7 (17) | 0.90 |
| Current alcohol abuse, n (%) | 8 (9) | 3 (7) | 0.71 |
| Previous antibiotic, n (%) | 24 (29) | 9 (22) | 0.43 |
| Influenza vaccine, n (%) | 12 (15) | 9 (22) | 0.29 |
| Pneumococcal vaccine, n (%) | 5 (6) | 2 (5) | >0.99 |
| BMI (kg/m2), mean ± SD | 25.7 ± 4.2 | 25.8 ± 5.7 | 0.89 |
| Co-morbidities, n (%) | |||
| Chronic respiratory disease | 20 (23) | 14 (33) | 0.22 |
| COPD | 2 (2) | 10 (24) | <0.001 |
| Asthma | 15 (17) | 4 (10) | 0.23 |
| Chronic cardiovascular disease | 7 (8) | 3 (7) | 0.84 |
| Diabetes mellitus | 7 (8) | 2 (5) | 0.48 |
| Neurological disease | 6 (7) | 2 (5) | 0.62 |
| Chronic liver disease | 2 (2) | 1 (2) | 0.98 |
| Chronic renal disease | 1 (1) | 1 (2) | 0.60 |
| Laboratory finding, median (IQR) | |||
| Serum creatinine (mg/dL) | 0.8 (0.7–1.0) | 0.9 (0.7–1.2) | 0.064 |
| Serum CK (U/L) | 90 (57–240) | 91 (54–152) | 0.67 |
| Serum LDH (U/L) | 501 (373–912) | 548 (403–900) | 0.81 |
| C-reactive protein (mg/dL) | 9.3 (5.1–19.2) | 14.9 (10.8–21.3) | 0.052 |
| Leukocyte count (109/L) | 7.3 (4.7–11.4) | 9.9 (6.1–14.7) | 0.037 |
| Platelets count (per mm3) | 180 (147–256) | 222 (169–292) | 0.014 |
| PSI risk class IV–V, n (%) | 6 (7) | 10 (24) | 0.007 |
| Severe CAP, n (%) | 26 (39) | 18 (44) | 0.60 |
| ICU admission, n (%) | 24 (28) | 14 (33) | 0.48 |
| PaO2/FIO2, median (IQR) | 288 (232–310) | 260 (162–311) | 0.40 |
| Mechanical ventilation, n (%) | 9 (11) | 9 (22) | 0.10 |
| Septic shock, n (%) | 17 (22) | 11 (28) | 0.46 |
| Multilobar infiltration, n (%) | 35 (43) | 17 (42) | 0.91 |
| Pleural effusion | 5 (6) | 2 (5) | 0.71 |
| ARDS criteria, n (%) | 6 (8) | 4 (10) | 0.59 |
| Hospital stay (days), median (IQR) | 5 (3–9) | 7 (4–9) | 0.036 |
| 30-day mortality, n (%) | 9 (11) | 3 (7) | 0.54 |
Abbreviations: COPD = chronic obstructive pulmonary disease; PSI = pneumonia severity index; IQR = interquartile range; LDH = lactate dehydrogenase; CAP = community-acquired pneumonia; ICU = intensive care unit; PaO2/FIO2 = arterial oxygen tension to inspired oxygen fraction ratio; ARDS = acute respiratory distress syndrome; BMI = body-mass index. Percentages were based on the number of patients with non-missing information.