The clinical features and outcome of 2009 H1N1 influenza infection in allo-SCT patients: a British Society of Blood and Marrow transplantation study

The clinical course of 2009 H1N1 influenza in Allo-SCT patients is unknown. Data were collected in the UK from October 2009 to April 2010 on laboratory-confirmed cases of H1N1 influenza in Allo-SCT recipients. H1N1 infection was diagnosed in 60 patients, median age 42 years, at a median of 10 months post-SCT. Twenty-one patients (35%) developed pneumonia and nine (15%) required admission to intensive care units. Actuarial mortality was 7% at 28 days and 19% 4 months post-diagnosis of 2009 H1N1 influenza. Increasing age and pre-existing lung disease were risk factors for pneumonia (P = 0.006 and 0.037, respectively); older age was a risk factor for death (P = 0.012). Morbidity and mortality from 2009 H1N1 influenza in SCT patients exceeds that of immunocompetent patients, but parallels that in other critically ill hospitalised cohorts; the elderly and those with chronic pulmonary disease are at greatest risk. Bone Marrow Transplantation (2012) 47, 88-94; doi: 10.1038/bmt.2011.12; published online 28 February 2011 Keywords: H1N1 influenza; Allo-SCT; immunocompromised; pneumonia; risk factors 3 (5)