OP-033 Prediction of elevated indirect hyperbilirubinemia and need for phototherapy using carboxyhemoglobin levels in the preterm neonate: a cross sectional analytical study

Aim To investigate the strength of COHb values in the first days of life to predict elevated indirect hyperbilluribinaemia in preterm deliveries. Material and Method A cross-sectional analytical study was conducted in preterm deliveries born <37 gestational weeks at NICU of Akdeniz University Faculty of Medicine. Demographic characteristics (pre-antenatal-postnatal data, preterm morbidities, and phototherapy requirement (if any) were recorded. Carboxy-hemoglobine (COHb), blood gas pH, pCO2, serum hemoglobin, albumin, total and direct bilirubin, reticulocyte(%), and direct coombs were obtained in the first 6th-24th and 48–96th hours. Group categorization was performed upon birthweight. Statistical analysis performed by SPSS 23.0 program included Chi-square/Fischer exact test for categorical variables, Mann Whitney-U test for continuous variables, Spearman correlation test to determine correlations within data measured at different time-periods. ROC analysis, followed by logistic regression model were used to determine COHb threshold values and independent risk factor for phototherapy requirements respectively. Results A total of 297 preterm neonates were included in the study. The rate of phototherapy was 50.8%. Blood-type incompatibility was present in 6.7% for ABO incompatibility and 4.7% for Rh incompatibility. Only three patients presented signs of hemolysis. Approximately 49.9% of neonates delivered phototherapy at the postnatal 2nd day. COHb levels at the 6th and 24th hours were not statistically significant in neonates who delivered phototherapy (p=0.075, p=0.099). ROC analysis determined the threshold level of COHb > 0.6 in the first 6 hours to predict the need for phototherapy with 72.19% sensitivity and 41.78% specificity (positive-predictive value: 56.2%, negative predictive value: 59.2%) (figure 1). COHb levels at 6th hours or 24th hours were not identified as independent risk factors in logistic regression models. Conclusions COHb values obtained in the first day of life were correlated with elevated indirect bilirubin in neonates born <37 weeks; however the performance of COHb in distinguishing the need for phototherapy was low.