Cord blood transfusions in extremely low gestational age neonates to reduce severe retinopathy of prematurity: results of a prespecified interim analysis of the randomized BORN trial

Preterm infants are at high risk for retinopathy of prematurity (ROP), with potential life-long visual impairment. Low fetal hemoglobin (HbF) levels predict ROP. It is unknown if preventing the HbF decrease also reduces ROP. BORN is an ongoing multicenter double-blinded randomized controlled trial investigating whether transfusing HbF-enriched cord blood-red blood cells (CB-RBCs) instead of adult donor-RBC units (A-RBCs) reduces the incidence of severe ROP (NCT05100212). Neonates born between 24 and 27 + 6 weeks of gestation are enrolled and randomized 1:1 to receive adult donor-RBCs (A-RBCs, arm A) or allogeneic CB-RBCs (arm B) from birth to the postmenstrual age (PMA) of 31 + 6 weeks. Primary outcome is the rate of severe ROP at 40 weeks of PMA or discharge, with a sample size of 146 patients. A prespecified interim analysis was scheduled after the first 58 patients were enrolled, with the main purpose to evaluate the safety of CB-RBC transfusions. Results in the intention-to-treat and per-protocol analysis are reported. Twenty-eight patients were in arm A and 30 in arm B. Overall, 104 A-RBC units and 49 CB-RBC units were transfused, with a high rate of protocol deviations. A total of 336 adverse events were recorded, with similar incidence and severity in the two arms. By per-protocol analysis, patients receiving A-RBCs or both RBC types experienced more adverse events than non-transfused patients or those transfused exclusively with CB-RBCs, and suffered from more severe forms of bradycardia, pulmonary hypertension, and hemodynamically significant patent ductus arteriosus. Serum potassium, lactate, and pH were similar after CB-RBCs or A-RBCs. Fourteen patients died and 44 were evaluated for ROP. Ten of them developed severe ROP, with no differences between arms. At per-protocol analysis each A-RBC transfusion carried a relative risk for severe ROP of 1.66 (95% CI 1.06-2.20) in comparison with CB-RBCs. The area under the curve of HbF suggested that HbF decrement before 30 weeks PMA is critical for severe ROP development. Subsequent CB-RBC transfusions do not lessen the ROP risk. The interim analysis shows that CB-RBC transfusion strategy in preterm neonates is safe and, if early adopted, might protect them from severe ROP. Prospectively registered at ClinicalTrials.gov on October 29, 2021. Identifier number NCT05100212.