Comparison of transcutaneous and plasma bilirubin measurement

Abstract

Objectives: To compare transcutaneous bilirubin measurements made using Bilicheck equipment with assays of capillary plasma using the Unistat bilirubinometer (Leica).

Methods: Two hundred concomitant assays were performed (transcutaneous and in plasma), and the correlation and level of agreement between them was calculated. An assessment was also made of the influence of birth weight, skin color, gestational age, postnatal age and phototherapy.

Results: The linear correlation coefficient was 0.92, and the mean difference between assays was 0.72 (+/-1.57) mg/dL, with a 95% confidence interval from -2.42 to +3.86. The best of a series of ROC curves demonstrated that transcutaneous assays at 14 mg/dL offer the best sensitivity (88.2%) and specificity (97.8%), with a positive predictive value of 78.9%, negative predictive value of 98.9 and are below the curve of 0.98.

Conclusions: Assays performed using Bilicheck can be substituted for capillary plasma assays up to 14 mg/dL. Above this level the device should only be used for screening for patients whose bilirubin should be assayed in blood.