Outcome at 30 days | Outcome at 60 days | |||||
Died | Survived | p-value | Died | Survived | p-value | |
Baseline characteristics | ||||||
Subjects n | 156 | 2493 | 183 | 2466 | ||
Age years median (IQR) | 74 (52–86) | 63 (41–79) | <0.001 | 73 (54–86) | 62 (41–79) | <0.001 |
Male sex | 97 (62.2) | 1273 (51.1) | 0.007 | 115 (62.8) | 1255 (50.9) | 0.002 |
Any comorbidity | 118 (75.6) | 1486 (59.6) | <0.001 | 141 (77.0) | 1463 (59.3) | <0.001 |
Virus strains | ||||||
H1N1pdm09 versus seasonal viruses# | 62 (40.5) | 899 (38.8) | 0.678 | 73 (40.8) | 888 (38.8) | 0.599 |
Influenza A versus B | 138 (88.5) | 2216 (88.9) | 0.869 | 162 (88.5) | 2192 (88.9) | 0.880 |
Complications | ||||||
Pneumonia | 137 (87.8) | 944 (37.9) | <0.001 | 155 (84.7) | 926 (37.6) | <0.001 |
Cardiovascular event | 20 (12.8) | 173 (6.9) | 0.006 | 27 (14.8) | 166 (6.7) | <0.001 |
Bacterial superinfection | 50 (32.1) | 236 (9.5) | <0.001 | 55 (30.1) | 231 (9.4) | <0.001 |
Treatments | ||||||
Antiviral treatment, any NAI | 106 (67.9) | 1885 (75.6) | 0.032 | 124 (67.8) | 1867 (75.7) | 0.016 |
Started within 2 days¶ | 42 (28.8) | 1118 (45.5) | <0.001 | 52 (30.1) | 1108 (45.6) | <0.001 |
Started within 5 days¶ | 72 (49.3) | 1634 (66.4) | <0.001 | 86 (49.7) | 1620 (66.6) | <0.001 |
Systemic corticosteroids+ | 60 (38.5) | 540 (21.7) | <0.001 | 70 (38.3) | 530 (21.5) | <0.001 |
Statin use+ | 11 (7.1) | 325 (13.0) | 0.029 | 16 (8.7) | 320 (13.0) | 0.097 |
Data are presented as n (%), unless otherwise stated. IQR: interquartile range; NAI: neuraminidase inhibitors. #: seasonal influenza viruses included A/H3N2, A/H1N1, B (subtyping data unavailable n=181); crude mortality was higher with H1N1pdm09 infection among patients aged <65 years (p=0.002). ¶: NAI treatment started within 2 days (versus >2 days and none) and 5 days (versus >5 days and none) from illness onset. Mortality at 30 days by NAI initiation time intervals for the whole cohort: NAI within 0–2 days (3.6%), 3–5 days (5.5%), >5 days (10.0%), none (7.6%); and for the pneumonia subgroup: NAI within 0–2 days (8.5%), 3–5 days (10.7%), >5 days (14.0%), none (18.9%); both p=0.001. +: corticosteroid use and mortality at 30 days in the pneumonia subgroup: 19.1% versus 10.6% (p<0.001), airway disease exacerbations subgroup: 6.0% versus 7.2% (p=0.683); statin use and mortality in the pneumonia subgroup: 9.6% versus 13.0% (p=0.289), airway disease exacerbations subgroup 0% versus 7.2% (p=0.056).