title: Children with Down syndrome are high-risk for severe respiratory syncytial virus disease.
abstract: OBJECTIVE
  To assess Down syndrome as an independent risk factor for respiratory syncytial virus (RSV) hospitalization in children younger than 3 years of age and to evaluate illness severity.
  
  
  METHODS
  A retrospective cohort study of children enrolled in the military health system database was conducted. The effect of Down syndrome on RSV hospitalization was assessed by Cox proportional hazards model, while we controlled for risk factors. Disease severity was assessed by length of hospital stay, need for respiratory support, and age at hospitalization.
  
  
  RESULTS
  The study included 633 200 children and 3 209 378 person-years. Children with Down syndrome had a hospitalization rate of 9.6% vs 2.8% in children without Down syndrome. Down syndrome had a greater adjusted hazard ratio (HR) for RSV hospitalization than most risk factors, 3.46 (95% CI 2.75-4.37). A sensitivity analysis demonstrated HR 3.21 (95% CI 2.51-4.10) for patients with Down syndrome ages 0-23 months and HR 5.07 (95% CI 2.21-11.59) ages 24-36 months. The median (IQR) length of stay of children with and without Down syndrome was 4 days (2-7) and 2 days (1-4) (P < .001). Patients with Down syndrome had a greater risk of requiring respiratory support (relative risk 5.5; 95% CI, 2.5-12.3). The median (IQR) ages at admission for children with and without Down syndrome were 9.8 months (5.5-17.7) and 3.5 months (1.7-8.7) (P < .001).
  
  
  CONCLUSIONS
  Down syndrome is independently associated with an increased risk for RSV hospitalization. Children with Down syndrome are older at time of RSV hospitalization and have more severe RSV illness than children without Down syndrome. This increased risk for hospitalization continues beyond 24 months.
authors.affiliation: Department of Pediatrics, Walter Reed National Military Medical Center, Bethesda, MD; Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, MD. Electronic address: david.r.stagliano.mil@health.mil.
authors.forename: David R
authors.initials: DR
authors.lastname: Stagliano
authors.affiliation: Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, MD.
authors.forename: Cade M
authors.initials: CM
authors.lastname: Nylund
authors.affiliation: Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, MD.
authors.forename: Matilda B
authors.initials: MB
authors.lastname: Eide
authors.affiliation: Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, MD.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Eberly
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000150:complications* / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006760:Hospitalization / Q000639:trends*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D015995:Prevalence; D018357:Respiratory Syncytial Virus Infections / Q000150:complications* / Q000453:epidemiology / Q000628:therapy; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D014481:United States