Follow-up of extreme neonatal hyperbilirubinaemia in 5- to 10-year-old children: a Danish population-based study.

AIM: To investigate whether infants with neonatal hyperbilirubinaemia but without intermediate or advanced bilirubin encephalopathy develop long-term sequelae, with impairment of motor development, executive function, or hearing. METHOD: This nested double-cohort study included 167 exposed children (107 males, 60 females) born in Denmark 2000 to 2005 at gestational age ≥35 weeks with a total serum bilirubin ≥450 µmol/L (26.3mg/dL) and 163 age-, sex-, and gestational age-matched unexposed children (103 males, 60 females). The children were examined at a mean age of 7.7 years (SD 1.7y) using the Movement Assessment Battery for Children-Second Edition (MABC-2), pure tone audiometry, and the Behavioural Regulation Inventory of Executive Function (BRIEF) questionnaire. RESULTS: The follow-up rate was 70% of the eligible infants in the exposed group and 45% in the unexposed group. Mean difference was -0.2 (95% confidence interval [CI] -1.1 to 0.8) in adjusted standard score for MABC-2 and 0.3 (95% CI -2.9 to 3.5) in adjusted BRIEF executive composite standard score. No children had significant hearing impairment or a diagnosis of cerebral palsy, attention-deficit-hyperactive disorder, or autism spectrum disorder recorded in national registries. INTERPRETATION: No evidence was found of an increased risk of deficits in motor development, executive function, or hearing in children with extreme hyperbilirubinaemia who did not have intermediate or advanced bilirubin encephalopathy.

[An update on unconjugated neonatal hyperbilirubinaemia in Denmark].

Approximately 60% of term newborn infants are jaundiced during the first week of life, which is caused by unconjugated bilirubin. Bilirubin encephalopathy is seen with severe hyperbilirubinaemia, when unbound bilirubin crosses the blood-brain barrier. The chronic form is called kernicterus spectrum disorder. To avoid this devastating condition, the treatment of choice for neonatal hyperbilirubinaemia is phototherapy, which is most efficient with LED light of 478-nm wavelength. In this review, we argue, that a systematic approach to hyperbilirubinaemic infants as well as surveillance of extreme neonatal hyperbilirubinaemia is highly important.

Extreme neonatal hyperbilirubinemia and kernicterus spectrum disorder in Denmark during the years 2000-2015.

OBJECTIVE: To determine the incidence and etiology of extreme neonatal hyperbilirubinemia, defined as total serum bilirubin (TSB) ≥450 µmol/L, and kernicterus spectrum disorder (KSD) in Denmark between 2000 and 2015. STUDY DESIGN: We identified all infants born between 01.01.2000 and 31.12.2015 with TSB ≥450 µmol/L, ratio of conjugated to TSB <0.30, gestational age ≥35 weeks, and postnatal age ≤4 weeks, using Danish hospitals' laboratory databases. RESULT: We included 408 infants. The incidence of extreme neonatal hyperbilirubinemia among infants with gestational age ≥35 weeks was 42/100,000 during the study period with a seemingly decreasing incidence between 2005 and 2015. Twelve of the 408 infants developed KSD, (incidence 1.2/100,000) Blood type ABO isohemolytic disease was the most common explanatory etiology. CONCLUSIONS: Our study stresses the importance of a systematic approach to neonatal jaundice and ongoing surveillance of extreme neonatal hyperbilirubinemia and KSD.

Extreme neonatal hyperbilirubinemia and a specific genotype: a population-based case-control study.

OBJECTIVES: Extreme hyperbilirubinemia (plasma bilirubin ≥ 24.5 mg/dL) is an important risk factor for severe bilirubin encephalopathy. Several risk factors for hyperbilirubinemia are known, but in a large number of patients, a causal factor is never established. UGT1A1 is the rate-limiting enzyme in bilirubin's metabolism. The genotype of Gilbert syndrome, the UGT1A1*28 allele, causes markedly reduced activity of this enzyme, but its association with neonatal hyperbilirubinemia is uncertain and its relationship with extreme hyperbilirubinemia has not been studied. We examined whether the UGT1A1*28 allele is associated with extreme hyperbilirubinemia. METHODS: The UGT1A1*28 allele was assessed in a case-control study of 231 white infants who had extreme hyperbilirubinemia in Denmark from 2000 to 2007 and 432 white controls. Cases were identified in the Danish Extreme Hyperbilirubinemia Database that covers the entire population. Genotypes were obtained through the Danish Neonatal Screening Biobank. Subgroup analysis was done for AB0 incompatible cases. RESULTS: No association was found between the UGT1A1*28 allele and extreme hyperbilirubinemia. With the common genotype as reference, the odds ratio of extreme hyperbilirubinemia was 0.87 (range, 0.68-1.13) for UGT1A1*28 heterozygotes and 0.77 (range, 0.46-1.27) for homozygotes. Also, no association was found for AB0 incompatible cases. CONCLUSIONS: The UGT1A1*28 allele was not associated with risk for extreme hyperbilirubinemia in this study.

Dose-response relationship of phototherapy for hyperbilirubinemia.

BACKGROUND AND OBJECTIVE: Using light-emitting diodes during conventional phototherapy, it is possible to reduce the distance from light source to infant, thus increasing light irradiance. The objective of this study was to search for a "saturation point" (ie, an irradiation level above which there is no further decrease in total serum bilirubin [TsB]). This was a prospective randomized study performed in the NICU of Aalborg Hospital, Denmark. METHODS: One hundred fifty-one infants (gestational age ≥ 33 weeks) with uncomplicated hyperbilirubinemia were randomized to 1 of 4 distances from the phototherapy device to the mattress (20, 29, 38, and 47 cm). TsB was measured before and after 24 hours of phototherapy and irradiance every eighth hour. Main outcome was 24-hour decrease of TsB expressed in percent, ( TsB(0-24), difference between TsB(0) and TsB(24) [%]). RESULTS: A highly significant linear relation was seen between light irradiance and TsB(0-24) (%) (P < .001): when the irradiance increased from 20 to 55 µW/cm(2)/nm, TsB(0-24) (%) increased from approximately 30% to 50%. In addition, smooth regression showed no tendency for TsB(0-24) (%) to level off as irradiance increased. TsB(0-24) (%) was negatively correlated to birth weight and positively to formula volume. Average weight gain during phototherapy was 1%, independent of light irradiance. CONCLUSIONS: By using light-emitting diodes, we found a linear relation between light irradiance in the range of 20 to 55 µW/cm(2)/nm and a decrease in TsB after 24 hours of therapy, with no evidence of a saturation point.

Follow-up of neonates with total serum bilirubin levels ≥ 25 mg/dL: a Danish population-based study.

OBJECTIVE: To study if severe hyperbilirubinemia in infants with no or minor neurologic symptoms in the neonatal period affects children's development at the age of 1 to 5 years. METHODS: Controlled descriptive follow-up study of a national cohort of Danish children. The exposed group consisted of all live-born infants in Denmark from 2004 to 2007 with a gestational age ≥ 35 weeks and severe hyperbilirubinemia in the neonatal period, defined as at least 1 measure of total serum bilirubin level ≥ 25 mg/dL during the first 3 weeks of life. The exposed group of 206 children was matched with a control group of 208 children. The Ages and Stages Questionnaire (ASQ), a method of evaluating the child's development, was filled in by parents. Main outcome measure was effect size of ASQ total score. Statistical analyses comprised a matched analysis of 102 pairs and a nonmatched regression analysis of all participants. RESULTS: The response rate was 79% (n = 162 of 206) in the study group and 70% (n = 146 of 208) in the control group. Neither the matched nor the nonmatched analysis showed any statistically significant differences between the groups; the effect size of the total score was 0.04 (-0.24 to 0.32) and -0.04 (-0.26 to 0.19), respectively. CONCLUSIONS: Using the parent-completed ASQ, we found no evidence of developmental delay in children aged between 1 and 5 years with severe neonatal hyperbilirubinemia compared with a matched control group.