Total bilirubin assay differences may cause inconsistent treatment decisions in neonatal hyperbilirubinaemia.

Abstract

To assess interlaboratory variability of total serum bilirubin (TSB) results in newborns. Initiated following a clinical incident in which a neonate was transferred to a tertiary hospital for treatment of severe hyperbilirubinemia but on arrival was reclassified into alower risk category due to a 20% difference in TSB between laboratories. Fresh residual plasma samples from hospital-born infants were pooled to obtain 11 samples across a range of total bilirubin concentrations. Aliquots were light-protected and measured on 7 commercial platforms at 4accredited medical laboratories. Data from The Royal College of Pathologists of Australasia Quality Assurance Programs' (RCPAQAP) Neonatal Bilirubin program was analysed. Twenty-four to 30% difference in results for individual samples, largely due to calibration differences between assays. When interpreted according to guidelines,results from different platforms would have ledto different clinical interventions in some cases. RCPAQAP results showed significant within-method bias but were not shown to be commutable with patient samples. There are clinically significant method-dependent differences in TSB results from neonatal samples, consistent with our clinical incident. The differences are largely due to lack of standardisation of calibrator values. Thishas implications for healthcare resource use and possiblyfor the neurodevelopment of infants. Intervention isneeded ata number of levels, including clinical reporting ofincidents arising from discordant results, commitment by manufacturers to ensure metrological traceability of methods with sufficiently low uncertainty in the final measurements, andavailability of commutable quality assurance material to monitor assay performance, especially at the clinical decision points for neonatal jaundice.