Direct Antiglobulin Test in Predicting the Severity of Hyperbilirubinemia and Haemolytic Disease of the Newborn

Abstract

This study investigated the efficacy of the Direct Antiglobulin Test (DAT) reaction grades and the severity of hyperbilirubinaemia, in order to assist with the prediction and treatment of HDN. However, a weak correlation was found in this study. DAT significance may be ambiguous and it is only when combined with clinical assessment may it aid in building a complete prognosis. This was supported from studies such as [1,2], who also believed that in isolation DAT significance is limited without other parameters such as, the Full Blood Count (FBC), Total Serum Bilirubim(TSB) , reticulocyte count and more importantly a clinical assessment.A total of 287 neonates were identified and eligible for the study over a 3 year period, 126 were female of which 77.8% with a negative DAT, 15.9% weakly positive (1+), 4.8% with a 2+ reaction strength and 1.6% as 3+ reaction. In comparison there were 161 male neonates with similar results with a negative DAT at 70.2%, 1.9% had an inconclusive DAT and 13% had an 1+ DAT reaction. The male neonates were around 3 times more likely to have a 2+ DAT at 11.8% than the female neonates and almost twice more likely to have a 3+ DAT. Both genders had a p-value of 0.92. There was a low prevalance of DAT positive neonates. The frequency of negative DAT made up 73.5% of the study population with a skewness 1.879. In total there were 76 (26.4%) of which 14.3% had a weakly positive (1+) DAT.The independent distribution of DAT positivity suggested non-parametric statistics application to the dataset. The DAT results were skewed (showing a disproportionate number of negative DAT results. However, this was also found in studies described by [3], who found only 37/303 neonates having a positive DAT.The limitations to the study were the small number of patients with a positive DAT, only having 2 patients with a positive DAT >3. With it being an observational study, a correlation between the DAT positivity and hyperbilirubinaemia and phototherapy was sought, however this could not be used to determine causality within the cohort as there was so much variations between the subjects and a follow up with neonates was not justified post discharge.