Clinical and economic evaluation of risk factor guided respiratory syncytial virus prophylaxis in Colombian preterm infants

BACKGROUND: The International Risk Scoring Tool (IRST) comprises three risk factors (age relative to the respiratory syncytial virus [RSV] season; household and/or maternal smoking; siblings and/or daycare attendance) and enables the cost-effective targeting of palivizumab to infants born at 32-35 weeks' gestational age (wGA) at greatest risk of related hospitalization (RSVH). This study provides the first evaluation of IRST-guided RSV prophylaxis in Colombia. METHODS: The IRST (with wGA substituted for chronological age as RSV is endemic in Colombia) plus other risk factors were assessed using data from 81 infants born 32-35 wGA with RSVH and 49 gestational- and age-matched controls. A cost-utility model comparing IRST-guided palivizumab versus no prophylaxis from the healthcare provider perspective was then adapted using Colombian costs and data (5% discounting). Infants could experience either RSVH, emergency room medically-attended, RSV infection, or remain uninfected/non-attended, with possible long-term respiratory morbidity up to 18 years of age over a lifetime time horizon. RESULTS: The most predictive combination of risk factors was the IRST plus mixed breast and formula feeding and maternal education (area under the receiver operating characteristic curve = 0.823). For infants assessed at moderate- and high-risk of RSVH, the cost/quality-adjusted life year (QALY) was COP20,225,126 (USD4,752). Probabilistic sensitivity analyses resulted in a mean of COP22,193,734/QALY (USD5,214/QALY), with a 61.1% probability of palivizumab being cost-effective at a COP28,193,734 (USD6,624; 2022 gross domestic product/capita) willingness-to-pay threshold. CONCLUSIONS: Palivizumab prophylaxis of 32-35 wGA infants at moderate- and high-risk of RSVH, identified using the Colombian-adapted IRST, proved to be cost-effective versus no intervention.