Discussion
BPD, death, NDI
LUNG DISEASE
In this analysis for heterogeneity of treatment effect in infants enrolled in the NICHD NRN Hydrocortisone Trial, baseline estimated risk for grades 2 to 3 BPD or death was not associated with the effect of hydrocortisone on observed grades 2 to 3 BPD or moderate or severe NDI or death. These findings are consistent with the primary analysis of the NICHD NRN Hydrocortisone Trial, which showed no effect of hydrocortisone on BPD or death or NDI or death.Our analysis was motivated by the multiple metaregression analyses of clinical trials of postnatal corticosteroids in preterm infants to prevent lung disease.While the overall results of a randomized clinical trial estimate the mean treatment effect for a therapy, an analysis for heterogeneity of treatment effect may identify a specific subpopulation for which there may be greater benefit or harm.Infants enrolled in the NICHD NRN Hydrocortisone Trial were at a particularly high risk for BPD or death. All required mechanical ventilation at 2 weeks’ postnatal age for inclusion in the trial. Therefore, the results of this analysis do not resolve whether there are potential differences in the effect of hydrocortisone in populations exposed at earlier postnatal ages or at different risks for BPD or death. In a randomized clinical trial of low-dose hydrocortisone (cumulative dose, 8.5 mg/kg) initiated within 24 hours after birth,There was no significant interaction for treatment effect by baseline risk for grades 2 to 3 BPD or death and the outcome of moderate or severe NDI or death in this analysis. Whereas previous evidence has supported a higher proportion of adverse childhood outcomes in infants with higher grades of BPD,