Revisiting ABO incompatibility as a risk factor for significant neonatal hyperbilirubinemia

Risk factors for readmission for hyperbilirubinemia in neonates with ABO hemolytic disease: a single-center retrospective cohort study

OBJECTIVE

ABO hemolytic disease of the newborn (ABO-HDN) is a major risk factor for severe hyperbilirubinemia, a common readmission reason for newborns. In this study, we aimed to assess the risk factors for readmission associated with hyperbilirubinemia in neonates with ABO-HDN.

METHODS

A retrospective cohort study was conducted including newborns with gestational age ≥35 weeks and ABO-HDN in 2018. Among 291 newborns, 36 were readmitted for hyperbilirubinemia and defined as the readmission group. The remaining 255 cases were used as a control group. We then performed between-group comparisons of clinical conditions associated with hyperbilirubinemia. Logistic regression was used to select risk predictors of readmission associated with hyperbilirubinemia due to ABO-HDN.

RESULTS

Baseline characteristics were similar between both groups (p > .05, respectively). However, total serum bilirubin (TSB) before initiating phototherapy was significantly higher in the readmission group when compared with that in the control group at 0-24 h, 24-48 h, and 48-72 h (183.70 µmol/L [interquartile range (IQR) 161.18-196.48] vs. 150.35 µmol/L [IQR 131.73-175.38], p = .005; 229.90 µmol/L [IQR 212.45-284.30] vs. 212.50 µmol/L [IQR 197.85-230.28], p = .026; 268.10 µmol/L [IQR 257.70-279.05] vs. 249.50 µmol/L [IQR 236.80-268.70], p = .045, respectively). The age of initiation of phototherapy in the readmission group was significantly lower than that in control group (30.0 h [IQR 18.0-49.00] vs. 42.0 h [IQR 23.0-61.0], p = .012). The rate of rebound hyperbilirubinemia after the first phototherapy treatment was significantly higher in the readmission group compared to that in the control group (9 [25%] vs. 13 [5.1%], p = .000), and the rate of positive direct antiglobulin testing was significantly higher than that in control group (17 [47.2%] vs. 74 [29.0%], p = .027). Logistic regression analysis showed that the age of initiation of photography, TSB level before the first phototherapy, and rebound hyperbilirubinemia after first phototherapy were independent risk factors for readmission in newborns with hyperbilirubinemia associated with ABO-HDN.

CONCLUSIONS

Earlier age of phototherapy initiation, higher TSB levels at the time of initiating phototherapy and rebound hyperbilirubinemia after the first phototherapy treatment may increase the risk of readmission for hyperbilirubinemia in neonates with ABO-HDN. These factors should be considered in discharge planning and follow-up for newborns with ABO-HDN associated hyperbilirubinemia.

Hour-Specific Total Serum Bilirubin Percentiles for Infants Born at 29-35 Weeks' Gestation

INTRODUCTION

As preterm infants are susceptible to hyperbilirubinemia, they require frequent close monitoring. Prior to initiation of phototherapy, hour-specific total serum bilirubin (TSB) percentile cut-points are lacking in these infants, which led to the current study.

METHODS

A multi-site retrospective cohort study of preterm infants born between January 2013 and June 2017 was completed at 3 NICUs in Ontario, Canada. A total of 2,549 infants born at 290/7-356/7 weeks' gestation contributed 6,143 pre-treatment TSB levels. Hour-specific TSB percentiles were generated using quantile regression, further described by degree of prematurity, and among those who subsequently received phototherapy.

RESULTS

Among all infants, at birth, hour-specific pre-treatment, TSB percentiles were 36.1 µmol/L (95% confidence interval [CI]: 34.3-39.3) at the 40th, 52.3 µmol/L (49.4-55.1) at the 75th, and 79.5 µmol/L (72.1-89.6) at the 95th percentiles. The corresponding percentiles were 39.3 μmol/L (35.9-43.2), 55.4 μmol/L (52.1-60.2), and 87.1 μmol/L (CI 70.5-102.4) prior to initiating phototherapy and 24.4 μmol/L (20.4-28.8), 35.3 μmol/L (31.1-41.5), and 52.0 μmol/L (46.1-62.4) among those who did not receive phototherapy. Among infants born at 29-32 weeks, pre-treatment TSB percentiles were 53.9 µmol/L (49.4-61.0) and 95.5 µmol/L (77.5-105.0) at the 75th and 95th percentiles, with respective values of 48.7 µmol/L (43.0-52.3), and 74.1 µmol/L (64.8-83.2) for those born at 33-35 weeks' gestation.

CONCLUSION

Hour-specific TSB percentiles, derived from a novel nomogram, may inform how bilirubin is described in preterm newborns. Further research of pre-treatment TSB levels is required before clinical consideration.