Early Haemoglobin Oxygen Affinity as a Hypothesis-Generating Marker for Retinopathy of Prematurity Risk in Preterm...

To investigate whether postnatal haemoglobin oxygen affinity (P₅₀), derived from serial arterial blood gases, is associated with the risk of retinopathy of prematurity (ROP) in preterm infants, as a potential physiologic marker.

Retrospective cohort study.

This study included 232 preterm infants born < 32 weeks gestation. Haemoglobin P₅₀ and lactate values were calculated daily during the first week of life. The primary outcome was the development of any ROP; treatment-requiring (Type 1) ROP was a secondary endpoint. Associations were analysed using logistic regression and ROC analysis.

Infants who developed ROP had significantly higher Day 7 P₅₀ values (mean 26.9 ± 1.8 mmHg) than those without ROP (26.1 ± 1.7 mmHg; p = 0.003). A Day 7 P₅₀ > 26.4 mmHg was independently associated with ROP (OR 2.5; 95% CI 1.3-4.9), though predictive performance was modest (AUC 0.60). Lactate levels showed no association with ROP. P₅₀ was not predictive of Type 1 ROP.

Increased postnatal P₅₀ may be modestly associated with ROP development, reflecting impaired oxygen delivery during early retinal vascularization. While not suitable for screening, P₅₀ may serve as a physiologic marker warranting further mechanistic investigation.