title: Pandemic H1N1 influenza-associated hospitalizations in children in Madrid, Spain.
abstract: OBJECTIVE
  To describe the epidemiological and clinical characteristics of children hospitalized with 2009 pandemic influenza (pH1N1) in Madrid, Spain.
  
  
  METHODS
  We included patients less than 14 years of age admitted to one of 18 hospitals in Madrid, Spain, between May 1 and November 30, 2009 and diagnosed with pH1N1 by polymerase chain reaction. A retrospective chart review was conducted and data were compared by age, presence of high-risk medical conditions, and pediatric intensive care unit (PICU) admission.
  
  
  RESULTS
  A total of 517 pH1N1 cases were included for final analysis. One hundred and forty-two patients (27·5%) had predisposing underlying illnesses, with immunosuppression (36 children, 7%) and moderate persistent asthma (34, 6·6%) being the most common ones. Patients with underlying medical conditions had longer hospital stays [median 5, interquartile range (IQR) 3-8 days, versus median 4, IQR 3-6, P < 0·001] and required intensive care (20·4% versus 5·9%, P < 0·001) and mechanical ventilation more frequently than previously healthy children. Globally, intensive care was required for 51 patients (10%) and invasive mechanical ventilation for 12 (2%). Pediatric intensive care unit admission was significantly associated with abnormal initial chest X-ray [Odds Ratio (OR) 3·5, 95% confidence interval (CI) 1·5-8·5], underlying neurological condition (OR 3·1, CI 1·2-7·5) and immunosuppression (OR 2·9, 1·2-6·8). Five patients (0·9%) died; two with severe neurological disease, two with leukemia, and one with a malignant solid tumor.
  
  
  CONCLUSIONS
  Children with underlying medical conditions experienced more severe pH1N1 disease. Risk factors for admission to the PICU included underlying neurological conditions, immunosuppression and abnormal initial chest X-ray.
authors.affiliation: Pediatrics Department, Hospital Infanta Elena, Valdemoro, Madrid, Spain. teredelrosal@yahoo.es
authors.forename: Teresa
authors.initials: T
authors.lastname: del Rosal
authors.forename: Fernando
authors.initials: F
authors.lastname: Baquero-Artigao
authors.forename: Cristina
authors.initials: C
authors.lastname: Calvo
authors.forename: María J
authors.initials: MJ
authors.lastname: Mellado
authors.forename: Juan C
authors.initials: JC
authors.lastname: Molina
authors.forename: María del Mar
authors.initials: Mdel M
authors.lastname: Santos
authors.forename: María J
authors.initials: MJ
authors.lastname: Cilleruelo
authors.forename: Mercedes
authors.initials: M
authors.lastname: Bueno
authors.forename: Pilar
authors.initials: P
authors.lastname: Storch de Gracia
authors.forename: Covadonga
authors.initials: C
authors.lastname: Terol
authors.forename: Miguel Á
authors.initials: MÁ
authors.lastname: Roa
authors.forename: Roi
authors.initials: R
authors.lastname: Piñeiro
authors.forename: Milagros
authors.initials: M
authors.lastname: García López-Hortelano
authors.forename: María L
authors.initials: ML
authors.lastname: García-García
authors.forename: Sonia
authors.initials: S
authors.lastname: Rodríguez
authors.forename: María
authors.initials: M
authors.lastname: Penín
authors.forename: Alejandro
authors.initials: A
authors.lastname: Zarauza
authors.forename: Francisco
authors.initials: F
authors.lastname: Alvarado
authors.forename: Ana
authors.initials: A
authors.lastname: de Blas
authors.forename: Enrique
authors.initials: E
authors.lastname: Otheo
authors.forename: Alfonso
authors.initials: A
authors.lastname: Rodríguez
authors.forename: María L
authors.initials: ML
authors.lastname: Herreros
authors.forename: Alfredo
authors.initials: A
authors.lastname: Tagarro
authors.forename: Luis
authors.initials: L
authors.lastname: Grande
authors.forename: José T
authors.initials: JT
authors.lastname: Ramos
authors.forename: Irene
authors.initials: I
authors.lastname: Maté
authors.forename: Cristina
authors.initials: C
authors.lastname: Muñoz
authors.forename: Miguel Á
authors.initials: MÁ
authors.lastname: Zafra
authors.forename: María P
authors.initials: MP
authors.lastname: Romero-Gómez
authors.forename: Elia
authors.initials: E
authors.lastname: Pérez-Fernández
authors.forename: Alberto
authors.initials: A
authors.lastname: Delgado
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Casas
authors.forename: María E
authors.initials: ME
authors.lastname: Cabezas
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D007251:Influenza, Human / Q000150:complications / Q000453:epidemiology* / Q000821:virology; D015278:Intensive Care Units, Pediatric / Q000706:statistics & numerical data; D008297:Male; D058873:Pandemics; D012189:Retrospective Studies; D013030:Spain / Q000453:epidemiology