40 Respiratory syncytial virus-related outcomes from an abbreviated palivizumab dose regimen in children with congenital heart disease

BACKGROUND: Respiratory Syncytial Virus (RSV) is a leading cause of hospital admission for acute lower respiratory tract infections (LRTI) in young children. Infants with congenital heart disease (CHD) are at a higher risk of severe infection, specifically those with hemodynamically significant intra-cardiac shunts, impaired cardiac function or pulmonary hypertension. Palivizumab prevents RSV-related hospitalizations in children with higher risk indications, including CHD, however the number of doses required to achieve optimal protection remains controversial. We report the clinical outcomes of children with CHD who received an abbreviated Palivizumab 4-dose schedule, with an increased inter-dose interval in our region. OBJECTIVES: To report hospitalization outcomes in children with CHD who received an abbreviated 4-dose Palivizumab dose schedule through the centrally managed regional RSV Immunoprophylaxis Program. DESIGN/METHODS: Retrospective population-based study of children with CHD enrolled into the regional RSV Program between 2012–2016. Children received palivizumab between November and April. Eligibility was defined according to our provincial guidelines and this defined our sample size. The primary outcome was in-season hospitalizations for RSV-confirmed or potentially RSV-related (unknown) LRTI determined by cross referencing the RSV Program database and the Canadian Institute of Health Informatics (CIHI) discharge abstract database (DAD) using seven RSV-related ICD-10 diagnostic codes. Children were categorized according to CHD subtype. Analysis was by intention-to-treat. RESULTS: A total of 325 children ([mean ± SD] gestational age 37.9±6.2 weeks; birth weight 2870±871 grams) were approved to receive 406 palivizumab courses. Between November 2012 and April 2016, 89 hospitalizations occurred in CHD patients. Of this, seventeen were RSV-confirmed hospitalizations (median age 5.9 [IQR 4 to 10]months); 8 additional cases were not tested for RSV, for a maximum rate of hospitalizationsfor RSV-confirmed or unknown of 6.2 per 100 approvals (95%CI: 4.0 to 9.0%). 24/25 RSV-confirmed or potentially RSV-related hospitalizations occurred before the 4(th)Palivizumab dose. Only one RSV-confirmed hospitalization occurred (52 days) after the 4th Palivizumab dose. Clinical characteristics of children with RSV-confirmed hospitalizations (n=17) were similar to those with RSV-unrelated hospitalizations (n=40). CONCLUSION: Our data provide population-based evidence of the protection achieved by a 4-dose Palivizumab dose schedule in infants with CHD. This clinical practice yields substantial benefits to children, their families, and to the health care system, such as reduced visits, injections, and costs, compared to a standard 5-dose schedule. Our results warrant confirmation in other geographic areas.