title: Outcomes of Infants Receiving Palivizumab Prophylaxis for Respiratory Syncytial Virus in Canada and Italy: An International, Prospective Cohort Study.
abstract: Respiratory syncytial virus (RSV) infection frequently results in RSV-related hospitalization (RSVH) in young infants. We examined the outcomes of palivizumab recipients within the Canadian Registry (CARESS) and the Torino-Verona Italian Registry over the 2002-2014 RSV seasons.
  
  
  
  RSVHs were captured during the study seasons. Premature infants who received palivizumab (≤35 completed weeks' gestational age; group1) were compared with infants given palivizumab for underlying disorders regardless of gestational age (group 2). Variables and between-group incidences were analyzed. Risk factors associated with RSVH were assessed by logistic regression.
  
  
  
  A total of 14,468 palivizumab-exposed infants were enrolled (group 1, n = 9093; group 2, n = 4856; miscellaneous, n = 519). RSVH was significantly more frequent in group 2 (211/4856, 4.34%) versus group 1 infants (216/9093, 2.37% [relative risk 1.93; 95% confidence interval (CI): 1.60-2.33; P < 0.0001]). Infants with neuromuscular disorders (7.88%), airway anomalies (5.95%), bronchopulmonary dysplasia (4.75%) and hemodynamically significant congenital heart disease (4.10%) had the highest RSVH incidences. After multivariable logistic regression, only neuromuscular disease [odds ratio [OR] 4.29; 95% CI: 2.30-8.00; P < 0.01], airway anomalies (OR 3.23; 95% CI: 1.92-5.43; P < 0.01), Down syndrome (OR 2.25; 95% CI: 1.31-3.89; P < 0.01), hemodynamically significant congenital heart disease (OR 2.24; 95% CI: 1.52-3.31; P < 0.001), prematurity ≤28 completed weeks' gestational age (OR 1.82; 95% CI: 1.29-2.58; P < 0.001) and bronchopulmonary dysplasia (OR 1.81; 95% CI: 1.31-2.50; P < 0.001) significantly predicted RSVH. No significant association was detected with the number of doses administered or the time elapsed after the previous dose.
  
  
  
  RSVH rates are higher in infants given palivizumab for reasons other than prematurity. It is uncertain whether these findings relate to inadequate current palivizumab dosing protocols or to a specific increased RSVH risk inherent in infants with severe underlying comorbidities.
authors.affiliation: From the *Neonatology and NICU, S. Anna Hospital, Torino, Italy; †Department of Pediatrics (Neonatal Division), McMaster University, Hamilton, Ontario, Canada; ‡Medical Outcomes and Research in Economics (MORE) Research Group, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; §Department of Paediatrics and Neonatology, "Silvio Orlandi" Hospital, Bussolengo, Verona, Italy; ¶Department of Pediatrics (Respirology Division), University of Calgary, Calgary, Alberta, Canada; and ‖Cancer Epidemiology Unit, Department of Medical Sciences, University of Torino, Torino, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Manzoni
authors.forename: Bosco
authors.initials: B
authors.lastname: Paes
authors.forename: Krista L
authors.initials: KL
authors.lastname: Lanctôt
authors.forename: Alberto
authors.initials: A
authors.lastname: Dall'Agnola
authors.forename: Ian
authors.initials: I
authors.lastname: Mitchell
authors.forename: Sara
authors.initials: S
authors.lastname: Calabrese
authors.forename: Milena
authors.initials: M
authors.lastname: Maule
authors.forename: Elisa
authors.initials: E
authors.lastname: Girardi
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Harimoto
authors.forename: Abby
authors.initials: A
authors.lastname: Li
mesh_terms: D000998:Antiviral Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D002170:Canada / Q000453:epidemiology; D006760:Hospitalization; D006801:Humans; D007231:Infant, Newborn; D007558:Italy / Q000453:epidemiology; D000069455:Palivizumab / Q000008:administration & dosage / Q000627:therapeutic use*; D011446:Prospective Studies; D018357:Respiratory Syncytial Virus Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000517:prevention & control*; D018113:Respiratory Syncytial Virus, Human; D012307:Risk Factors
chemical_list: D000998:Antiviral Agents; D000069455:Palivizumab