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

## TL;DR

This study shows that using a risk scoring tool to guide RSV prophylaxis in preterm infants in Colombia is cost-effective.

## Contribution

The first evaluation of the IRST-guided RSV prophylaxis in Colombia for preterm infants.

## Key findings

- The IRST plus additional factors predicted RSV hospitalization risk with high accuracy (AUC = 0.823).
- Palivizumab prophylaxis was cost-effective at COP20,225,126 per QALY for moderate- and high-risk infants.
- Probabilistic analysis showed a 61.1% probability of cost-effectiveness at the GDP/capita threshold.

## Abstract

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.

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.

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.

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.

The online version contains supplementary material available at 10.1186/s12962-025-00710-z.