title: Down syndrome: a novel risk factor for respiratory syncytial virus bronchiolitis--a prospective birth-cohort study.
abstract: OBJECTIVE
  Respiratory syncytial virus is the single-most important cause of lower respiratory tract infections in children. Preterm birth and congenital heart disease are known risk factors for severe respiratory syncytial virus infections. Although Down syndrome is associated with a high risk of respiratory tract infections, little is known about the incidence of respiratory syncytial virus infections in this group. The aim of our study was to determine the incidence of respiratory syncytial virus lower respiratory tract infection-associated hospitalization among children with Down syndrome.
  
  
  METHODS
  We performed a retrospective observational study and a prospective nationwide birth-cohort study of children with Down syndrome. The retrospective cohort comprised 176 children with Down syndrome. A birth cohort of 219 children with Down syndrome was prospectively followed until 2 years of age. All 276 siblings of the birth cohort were used as controls.
  
  
  RESULTS
  Of the 395 patients with Down syndrome, 180 (45.6%) had a known risk factor for severe respiratory syncytial virus infections; 39 (9.9%) of these were hospitalized for respiratory syncytial virus lower respiratory tract infections. Two control children (0.7%) versus 9 term children with Down syndrome without congenital heart disease (7.6%) were hospitalized for respiratory syncytial virus lower respiratory tract infections. The median duration of hospitalization was 10 days; mechanical ventilation was required for 5 children (12.8%).
  
  
  CONCLUSIONS
  This is the first study, to our knowledge, to demonstrate that Down syndrome is a novel independent risk factor for severe respiratory syncytial virus lower respiratory tract infections. These findings should prompt studies to investigate possible mechanisms that underlie severe respiratory syncytial virus lower respiratory tract infections in children with Down syndrome. The effect of respiratory syncytial virus prophylaxis in this specific population needs to be established.
authors.affiliation: Division of Infectious Diseases, University Medical Centre Utrecht, Department of Pediatrics, 3508 AB, Utrecht, The Netherlands.
authors.forename: Beatrijs L P
authors.initials: BL
authors.lastname: Bloemers
authors.forename: A Marceline
authors.initials: AM
authors.lastname: van Furth
authors.forename: Michel E
authors.initials: ME
authors.lastname: Weijerman
authors.forename: Reinoud J B J
authors.initials: RJ
authors.lastname: Gemke
authors.forename: Chantal J M
authors.initials: CJ
authors.lastname: Broers
authors.forename: Kimberly
authors.initials: K
authors.lastname: van den Ende
authors.forename: Jan L L
authors.initials: JL
authors.lastname: Kimpen
authors.forename: Jan L M
authors.initials: JL
authors.lastname: Strengers
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Bont
mesh_terms: D000293:Adolescent; D000328:Adult; D001990:Bronchiolitis, Viral / Q000453:epidemiology*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007223:Infant; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D010102:Oxygen Inhalation Therapy / Q000706:statistics & numerical data; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012136:Respiratory Syncytial Viruses; D012189:Retrospective Studies; D012307:Risk Factors