Enteral High-dose DHA Supplementation on Bronchopulmonary Dysplasia in Very Preterm Infants: a Collaborative Study

This one-stage individual participant data (IPD) meta-analysis study will aim to determine whether high-dose docosahexaenoic acid (DHA) enteral supplementation during the neonatal period is associated with the risk for severe bronchopulmonary dysplasia (BPD) at 36 weeks' postmenstrual age (PMA) compared to control, in contemporary cohorts of preterm infants born at less than 29 weeks of gestation. The association between high-dose DHA and severe BPD will also be explored in important subgroups according to sex, gestational age, small-for-gestational age and mode of delivery.

Severe BPD is a well-known factor consistently associated with impaired cognitive outcomes. Regarding reported benefits on long-term neurodevelopmental outcomes, the potential adverse effects of high-dose DHA supplementation on this short-term neonatal morbidity needs further investigations in infants born very preterm.

Therefore, based on previous systematic review findings and a known association between more severe BPD and unfavorable neurodevelopmental outcomes, a deeper understanding of the association between DHA and severe BPD needs further investigations. Harmonization of the severe BPD definition across the recent DHA trials, reclassified according to modern criteria will strengthen the results and allow their interpretation in balance with the potential efficacy of DHA on long-term neurodevelopmental outcomes. Moreover, inconsistent differential responses of DHA on BPD were previously reported according to subgroups such as sex, gestational age and mode of delivery and need to be further explored in this more vulnerable population.

Eligibility Criteria:
Trials included in our prior systematic review and traditional meta-analysis will be eligible for this IPD meta-analysis if they were registered randomized clinical trials of infants born preterm at less than 29 weeks of gestation and with adequate levels of blinding and allocation concealment. Moreover, eligibility will be restricted to trials conducted in a population of infants born after 2010 receiving contemporary respiratory care, similar to Jensen's cohort within which the severity-based definition of BPD was developed.

The intervention has to involve enteral administration of high-dose DHA supplementation during the neonatal period. A high-dose DHA supplementation is defined as direct enteral DHA supplementation at a dose of at least 40 mg/kg/day or DHA supplementation of breast milk or formula aiming for at least 0.4% of total fatty acids. The intervention should be randomly assigned as either enteral administration of high-dose DHA supplementation OR a control with no or low-dose DHA.

Trials evaluating intravenous DHA interventions or combined interventions (e.g. DHA combined to other nutrients or long-chain polyunsaturated fatty acids) are not considered for inclusion in this IPD meta-analysis to isolate the DHA effects and avoid heterogeneity in the intervention.

The IPD meta-analysis will be conducted using a harmonized severity-based definition of BPD in eligible trials. This definition will be based on Jensen's criteria that adequately predict childhood outcomes in a contemporary cohort of infants born very preterm. To be included, prospectively collected data from eligible trials should allow BPD severity outcome classification and harmonization according to Jensen's severity-based BPD criteria at 36 weeks' PMA.