RT Journal Article SR Electronic T1 Influenza pneumonia: a comparison between seasonal influenza virus and the H1N1 pandemic JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 106 OP 111 DO 10.1183/09031936.00125910 VO 38 IS 1 A1 R. Riquelme A1 A. Torres A1 M.L. Rioseco A1 S. Ewig A1 C. Cillóniz A1 M. Riquelme A1 C. Inzunza A1 E. Polverino A1 Y. Gomez A1 M.A. Marcos A1 C. Contreras A1 A. Gabarrús A1 R. Fasce YR 2011 UL http://erj.ersjournals.com/content/38/1/106.abstract AB We compared clinical presentation, complications and outcome in patients with influenza A (H1N1) and seasonal influenza pneumonia. The group of patients with influenza A (H1N1) pneumonia consisted of 75 patients. 52 patients with pneumonia associated with seasonal influenza were included for comparison. Patients with pneumonia associated with novel H1N1 influenza were younger (mean age 39.7 yrs versus 69.6 yrs) and had fewer chronic comorbidities and less alcoholism. Infiltrates were more extensive and frequently interstitial. Respiratory failure was more frequent (those with an arterial oxygen tension/inspiratory oxygen fraction ratio <200 28% versus 12%, p = 0.042), leading to a higher rate of intensive care unit (ICU) admission and mechanical ventilation (29.3% versus 7.7% (p<0.0030) and 18.7% versus 2% (p<0.0045)). Mortality was twice as high in patients with novel H1N1 (12% versus 5.8%; p = 0.238), although this was not significant, and was attributable to pneumonia in most instances (77.8% versus 0%; p = 0.046). Younger age, fewer comorbidities, more extensive radiographic extension and more severe respiratory compromise, and ICU admissions are key features of the clinical presentation of patients with novel H1N1-associated pneumonia compared with seasonal influenza pneumonia.