Increasing Rates of RSV Hospitalization among Preterm Infants: A Decade of Data

In 2014, the American Academy of Pediatrics (AAP) changed its policy on the use of respiratory syncytial virus immunoprophylaxis (RSV-IP) so that RSV-IP was no longer recommended for use among infants without other medical conditions born >29 weeks of gestational age (wGA). This study examines 10-year trends in RSV-IP and RSV hospitalizations among term infants and preterm infants born at 29 to 34 wGA, including the 5 RSV seasons before and 5 RSV seasons after the AAP guidance change.

A retrospective observational cohort study of a convenience sample of infants less than 6 months of age during RSV season (November-March) born between July 1, 2008, and June 30, 2019, who were born at 29 to 34 wGA (preterm) or >37 wGA (term) in the IBM MarketScan Commercial and Multi-State Medicaid databases. We excluded infants with medical conditions that would independently qualify them for RSV-IP. We identified RSV-IP utilization along with RSV and all-cause bronchiolitis hospitalizations during each RSV season. A difference-in-difference model was used to determine if there was a significant change in the relative rate of RSV hospitalizations following the 2014 policy change.

There were 53,535 commercially insured and 85,099 Medicaid-insured qualifying preterm infants and 1,111,670 commercially insured and 1,492,943 Medicaid-insured qualifying term infants. Following the 2014 policy change, RSV-IP utilization decreased for all infants, while hospitalization rates tended to increase for preterm infants. Rate ratios comparing preterm to term infants also increased. The relative rate for RSV hospitalization for infants born at 29 to 34 wGA increased significantly for both commercially and Medicaid-insured infants (1.95, 95% CI: 1.67-2.27, p <0.001; 1.70, 95% CI: 1.55-1.86, p <0.001, respectively). Findings were similar for all-cause bronchiolitis hospitalizations.

We found that the previously identified increase in RSV hospitalization rates among infants born at 29 to 34 wGA persisted for at least 5 years following the policy change.

· Immunoprophylaxis rates decreased after the 2014 American Academy of Pediatrics guidelines update.. · Rate of RSV hospitalization increased among preterm infants after the 2014 AAP guidelines update.. · Increase in RSV hospitalization persisted for at least 5 years after AAP guidelines update..