Objective: To establish the preterm infant hospitalization risks from respiratory syncytial virus (RSV) in New Zealand and the net cost per hospitalization averted by palivizumab.
Methods: The 437 infants born < 32 weeks gestation in 1997 and treated at five major neonatal units were identified. Subsequent admissions during the next 2 years for bronchiolitis, pneumonia and croup were tracked, and information collected on RSV tests performed. Data on the length of stay and hospital costs were used to calculate the potential net cost per hospitalization averted associated with the use of palivizumab and the number needed to treat (NNT) to prevent one hospitalization.
Results: Estimated RSV readmission risk before 1 year corrected age in infants < 32 weeks gestation discharged home on oxygen, and those ≤ 28 weeks gestation, or between 29 and 31 weeks gestation with or without chronic lung disease was 42%, 23%, 19%, 10% and 8%, respectively. The NNT with palivizumab to prevent one hospitalization ranged from six to 26 across subgroups. Mean (range) net cost per hospitalization averted was $NZ60 000 ($28 600−$166 700). In no subgroup would prophylaxis result in net cost saving. Prophylaxis for all NZ infants ≤ 28 weeks gestation would cost approximately $1 090 000 net and prevent 29 hospitalizations annually, being equivalent to $37 000 net per hospitalization averted, with eight infants treated to prevent one hospitalization. Alternative assumptions about cost and efficacy failed to alter these findings.
Conclusion: If value is placed on preventing morbidity, the priority groups for palivizumab prophylaxis are preterm infants discharged home on oxygen, followed by preterm infants of 28 weeks gestation or less.