OBJECTIVES: To examine the potential impact of utilizing the 3-risk factor International Risk Scoring Tool (IRST: age in relation to respiratory syncytial virus [RSV] season, maternal/household smoking and siblings/daycare) to target prophylaxis against severe RSV infection rather than the current, sole criterion of the presence of sibling(s) on the cost-utility of palivizumab (versus no prophylaxis) in Korean infants born 32–35 weeks’ gestational age (wGA).

METHODS: A previously published cost-utility model was adapted for the Korean setting using, where available, country-specific parameters. Infants experienced either RSV-related hospitalization (RSVH), emergency room/outpatient medically-attended RSV infection (MARI), or remained uninfected/non-attended. RSVH rates were predicted using the database (N=13,475) that generated the IRST: 6.3% for infants who had high- and moderate-risk scores by the IRST and 1.8% for infants with sibling(s), discounting all other risk factors. Palivizumab efficacy at reducing RSVH was 82.2% (IMpact-RSV trial). Mortality (0.43%) was applied only to infants admitted to intensive care (4.5% of RSVH infants). Prophylaxis costs were calculated using Korean prices, published birthweights and a growth algorithm. The model adopted the healthcare provider perspective and included the possibility of respiratory morbidity up to 18 years over a lifetime horizon (4.5% discounting).

RESULTS: The cost/quality-adjusted life year for prophylaxis of infants scored moderate- and high-risk by the IRST was ₩26,166,959 ($19,912) versus ₩33,268,100 ($25,316) when using siblings alone. Probabilistic sensitivity analyses (10,000 iterations) resulted in a 75.6% probability of cost-effectiveness for IRST-guided prophylaxis and 66.5% probability for siblings-guided prophylaxis against a threshold of ₩45,990,609 (USD $34,998), the gross domestic product per capita of Korea.

CONCLUSIONS: Risk factor-guided prophylaxis of Korean infants born 32-35wGA is a cost-effective strategy versus no prophylaxis. Utilization of the IRST provides an alternative approach to using siblings as the sole criterion for prophylaxis, and may result in improved targeting of at-risk infants and, thereby, cost-effectiveness.