115: Factors Associated with Compliance with Palivizumab Prophylaxis in the Canadian RSV Evaluation Study for Synagis (Caress) Registry (2005–2013)

Abstract

Background: CARESS is a prospective registry that documents utilization, compliance and health outcomes of all Canadian infants who received >1 dose of palivizumab for respiratory syncytial virus (RSV) prophylaxis across 32 sites during the 2005-2013 RSV seasons. Objectives: To determine factors associated with palivizumab compliance among recruited infants. Design/Methods: Neonatal and demographic data were collected at enrolment. Hospitalizations related to respiratory illness (RIH) and RSVrelated infection (RSVH) were collected monthly. Compliance was defined as receipt of all expected injections at 25 to 35 day intervals during the season. Logistic regression was used to assess independent predictors of compliance. Results: 16,290 infants received an average of 90.5+/-18.2% of expected injections and 73.3% were within appropriate time intervals. Compliance differed between indications for prophylaxis (chi 2 =22.717, P<0.0005). Premature infants <35 weeks gestational age had the highest compliance (7864 of 10,576 [74.4%]), followed by infants with chronic lung disease (949 of 1290 [73.6%]), those with other pre-existing medical disorders (1915 of 2666 [71.8%]), and infants with hemodynamically significant congenital heart disease (1220 of 1758 [69.4%]). Factors independently associated with compliance (OR [95% CI]; P value) were: household crowding (1.13 [1.04 to 1.23]; P=0.005), siblings (1.11 [1.03 to 1.21]; P=0.006), maternal smoking (0.81 [0.74 to 0.90]; P<0.0005) and Aboriginal status (0.74 [0.62 to 0.89]; P=0.002). After adjusting for risk factors, compliance was significantly associated with lower hazard rates of RIH (0.85 [0.74 to 0.96]; P=0.012), but not RSVH (0.97 [0.95 to 1.70]; P=0.83). Conclusions: In the CARESS registry, compliance with RSV prophylaxis across eight RSV seasons is associated with several, known demographic and environmental risk factors including Aboriginal status. Better compliance resulted in lower RIH hazard rates though the effect on RSVH was insignificant.