Comparison of Bilirubin Induced Neurologic Dysfunction Score with Brainstem Auditory Evoked Response in Detecting Acute Bilirubin Encephalopathy in Term Neonates

Abstract

Introduction: Brainstem Auditory Evoked Response (BAER) is an effective and objective hearing screening method in new-borns, especially those with Bilirubin Encephalopathy (BE). The most common and earliest manifestation of bilirubin neurotoxicity is involvement of the auditory nerve. This, often ‘silent’ sequel is sometimes missed, but can be detected early using BAER. The Bilirubin Induced Neurologic Dysfunction (BIND) score has been proposed to facilitate the clinical diagnosis of this disorder. Aim: To determine the effectiveness of BAER and BIND score in detecting Acute Bilirubin Encephalopathy (ABE) amongst neonates with hyperbilirubinaemia. Materials and Methods: A cross-sectional study involving 132 consecutive term neonates (66 neonates with Total Serum Bilirubin (TSB) ≥10.0 mg/dL and 66 age and sex matched controls) was conducted. Eligible neonates were subjected to BAER immediately after sample for bilirubin was taken and BIND scoring was done. The data was analysed with SPSS version 21. The mean, standard deviation and t-test was calculated for continuous data, while percentages and Chi-square test or fisher’s-exact test (where applicable) were computed for categorical variables. The sensitivity, specificity, predictive values of the BIND score relative to BAER and Receiver Operator Characteristic (ROC) curve analysis were also calculated. The level of statistical significance was set at p≤0.05. Results: The mean gestational age at birth of cases was 39.1±0.8 weeks, and 39.1±0.7 weeks for healthy controls. The age range of the neonates at presentation was between 24 hours to 15 days, with the mean age of neonates with hyperbilirubinaemia was 5.17±2.1 days while that of the healthy controls was 5.98±2.8. Thirty-six (54.5%) males and 30 (45.5%) females with hyperbilirubinaemia were enrolled (M:F 1.2:1), similar to 35 (53%) females and 31 (47%) males amongst the control group (M:F=1:1.1). The sensitivity and specificity of the BIND score relative to BAER was 93.8% and 90% respectively, with an area of 0.96 by ROC analysis. The BIND score had a positive predictive value of 75%, negative predictive value of 97.8% and an overall diagnostic accuracy of 90.9%. Conclusion: BAER audiometry and BIND score are useful diagnostic tools in detecting ABE. The BIND score is a reliable surrogate where BAER is not available to detect ABE.

Keywords

• bilirubin neurotoxicity
• bilirubin induced neurologic dysfunction score
• hyperbilirubinaemia