title: [Multi-center investigation of the hospitalized children with 2009 influenza A (H1N1) infection].
abstract: OBJECTIVE
  The pandemic influenza in 2009 was caused by a new virus, influenza A (H1N1) virus which has never been found in human before. The papers published at different time, in different places by authors from different institutions show different clinical features. Herein, we describe the clinical features of hospitalized children with 2009 influenza A (H1N1) infection from multi-centers all over the country retrospectively.
  
  
  METHODS
  Clinical data of 810 cases with 2009 influenza A (H1N1) infection were collected from 17 hospitals. The clinical characteristics, laboratory abnormalities, treatment and outcomes were retrospectively studied.
  
  
  RESULTS
  Of the 810 hospitalized children with 2009 influenza A (H1N1) infection, 508 (62.7%) were male, 302 (37.3%) female; the median age was 43 months, 550 (67.9%) were under 5 years of age; 148 (18.5%) had underlying chronic disease. The common presenting symptoms were fever (96.3%), runny nose (36.3%), stuffiness (23.7%), sore throat (18.1%), cough (93.7%), sputum (42.8%), wheezing (27.0%), dyspnea (20.1%), vomiting (16.0%), diarrhea (8.1%), irritability (9.8%), lethargy (7.9%) and seizures (4.0%). The common laboratory abnormalities were abnormal results of white blood cells counts (46.5%), elevations of lactate dehydrogenase (LDH, 42.7%), elevated C-reactive protein (CRP, 37.8%), aspartate transaminase (AST, 31.7%) and creatine kinase (CK, 21.5%). Clinical complications included pneumonia 586 (72.3%), encephalopathy/encephalitis 49 (6.0%), and myocarditis 30 (3.7%); 183 children had critical illness. The incidence of having underlying chronic disease, leukocytosis, neutrophilia, lymphopenia and elevations of CRP were high in critically ill patients. Totally 19 (2.3%) died, 8 died from encephalopathy/encephalitis; 10 died from severe pneumonia and ARDS, of whom 5 patients were complicated with encephalopathy/encephalitis; 1 died from secondary fungal meningitis.
  
  
  CONCLUSIONS
  Hospitalized children with 2009 influenza A (H1N1) infection may have a wide involvement of organ systems. The risk factors for critical illness were having underlying chronic disease, leukocytosis, neutrophilia, lymphopenia and elevations of CRP. Complications of severe pneumonia, ARDS, and encephalopathy/encephalitis were main causes of death.
mesh_terms: D000293:Adolescent; D002648:Child; D002673:Child, Hospitalized; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D008297:Male; D012189:Retrospective Studies; D012307:Risk Factors