title: Hospitalization for respiratory syncytial virus illness in Down syndrome following prophylaxis with palivizumab.
abstract: BACKGROUND
  Down syndrome (DS) is a risk factor for respiratory syncytial virus (RSV) hospitalization, but little is known about prophylaxis in these children.
  
  
  METHODS
  CARESS is a prospective registry of children who received ≥1 dose of palivizumab during the 2006-2012 RSV seasons across 32 sites in Canada. The objective was to compare respiratory illness hospitalization and RSV hospitalization (RSVH) hazard ratios in DS children aged <2 years who received palivizumab versus children who received prophylaxis for standard indications (SI) and for other medical illnesses (MI).
  
  
  RESULTS
  13,310 children were enrolled; DS (600; 4.5%), SI (11,081; 83.3%) and MI (1629, 12.2%), with DS children increasing over the duration from 0.1% (2006) to 4.5% (2012). Participants were significantly different in mean birth weight, gestational and enrollment age and risk factors. Children in each group received an average of 4.3 ± 1.4 (DS), 4.1 ± 1.6 (SI) and 4.5 ± 1.4 (MI) palivizumab injections per RSV season, with DS, differing significantly from SI [F(2, 13,307) = 43.6, P = 0.01] but not MI [F(2, 13 307) = 43.6, P = 0.07]. Compliance rates were similar across the groups. While a significantly greater proportion of SI children had RIHs compared with DS, [hazard ratio: 0.64 (0.48-0.84); P = 0.001] hazard ratios were similar for DS and MI. RSVH incidence rates were: 1.53%, 1.45% and 2.27% for DS, SI and MI, respectively. Neither group nor compliance affected time to RSVH.
  
  
  CONCLUSIONS
  The proportion of DS children who received palivizumab in CARESS has increased almost 45-fold. RSVH rates were low in DS following prophylaxis and hazards were similar to those found in SI and MI.
authors.affiliation: From the *Department of Pediatrics, McMaster University, Hamilton, Ontario; †Department of Pediatrics, University of Calgary, Calgary, Alberta; and ‡Medical Outcomes and Research in Economics (MORE®) Research Group, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Bosco
authors.initials: B
authors.lastname: Paes
authors.forename: Ian
authors.initials: I
authors.lastname: Mitchell
authors.forename: Hao
authors.initials: H
authors.lastname: Yi
authors.forename: Abby
authors.initials: A
authors.lastname: Li
authors.forename: Krista L
authors.initials: KL
authors.lastname: Lanctôt
mesh_terms: D019072:Antibiotic Prophylaxis; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D000998:Antiviral Agents / Q000627:therapeutic use*; D002170:Canada / Q000453:epidemiology; D004314:Down Syndrome / Q000453:epidemiology* / Q000821:virology*; D005260:Female; D006760:Hospitalization; D006801:Humans; D007223:Infant; D008297:Male; D000069455:Palivizumab; D011446:Prospective Studies; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology* / Q000517:prevention & control*; D016896:Treatment Outcome
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000998:Antiviral Agents; D000069455:Palivizumab