Transcutaneous bilirubinometers and ethnicity

Differences Between Transcutaneous and Serum Bilirubin Measurements in Black African Neonates

BACKGROUND AND OBJECTIVE

Transcutaneous bilirubin (TcB) correlates positively with total serum bilirubin (TSB) across different racial populations. However, little is known about the pattern of divergence between TcB and TSB at individual patient-level and the relationship with TcB measuring techniques among African neonates. This study, therefore, investigates TcB-TSB discrepancies and the contribution of 2 models of transcutaneous bilirubinometers to the observed divergence in a black African population.

METHODS

Medical records were retrieved for late preterm and term infants with 1 to 3 pairs of TcB and TSB measurements between December 2011 to June 2015 in Nigeria. Divergence between TcB and TSB values for each infant was determined and the associated factors explored with generalized estimating equations for logistic regression. Contributions of BiliChek and JM-103 transcutaneous bilirubinometers to the divergence were further explored through linear regression and Bland-Altman analysis.

RESULTS

Overall, 2107 TcB/TSB measurements from 1553 infants were analyzed. TSB was overestimated by ≥2 mg/dL in 64.5%, ≥3 mg/dL in 42.7%, and ≥4 mg/dL in 25.7% of all measurements. In contrast, TSB was underestimated by ≥2 mg/dL in 1.1%, ≥3 mg/dL in 0.5%, and ≥4 mg/dL in 0.3% of all recordings. Postnatal age, feeding mode, and type of TcB instrument were predictive of TSB overestimation. The JM-103 was associated with greater imprecision than BiliChek at all TSB levels.

CONCLUSIONS

BiliChek and JM-103 bilirubinometers significantly overestimate TSB in black African neonates and may result in unnecessary or excessive treatments. Additional development of appropriate bilirubin determination devices for this racial group, especially in resource-limited settings, is warranted.

Transcutaneous bilirubinometry

Although the modern era of transcutaneous bilirubin monitoring (TcB) began only about 35 years ago, this screening tool is now widely used in newborn nurseries and outpatient clinics, offices, and emergency departments to obtain a rapid and non-invasive estimate of the degree of hyperbilirubinemia. TcB devices have become more sophisticated, and major breakthroughs include the following: (a) ability to report a bilirubin value rather than an index value, (b) enhanced correction for chromophores other than bilirubin, and (c) technologic improvements including interface with electronic medical records. Good agreement with laboratory bilirubin measurement has been demonstrated, and the ability of TcB screening to predict and decrease the incidence of subsequent hyperbilirubinemia has been well-documented. To date, it has not been shown that this screening results in improved long-term outcomes.

Comparison of a new transcutaneous bilirubinometer (Bilimed) with serum bilirubin measurements in preterm and full-term infants

Background

The gold standard to assess hyperbilirubinemia in neonates remains the serum bilirubin measurement. Unfortunately, this is invasive, painful, and costly. Bilimed^®, a new transcutaneous bilirubinometer, suggests more accuracy compared to the existing non-invasive bilirubinometers because of its new technology. It furthermore takes into account different skin colours. No contact with the skin is needed during measurement, no additional material costs occur. Our aim was to assess the agreement between the Bilimed^® and serum bilirubin in preterm and term infants of different skin colours.

Methods

The transcutaneous bilirubin measurements were performed on the infant's sternum and serum bilirubin was determined simultaneously. The agreement between both methods was assessed by Pearson's correlation and by Bland-Altman analysis.

Results

A total of 117 measurement cycles were performed in 99 term infants (group1), further 47 measurements in 38 preterm infants born between 34 - 36 6/7 gestational weeks (group 2), and finally 21 measurements in 13 preterm infants born between 28 - 33 6/7 gestational weeks (group 3). The mean deviation and variability (+/- 2SD) of the transcutaneous from serum bilirubin were: -14 (+/- 144) μmol/l; -0.82 (+/- 8.4) mg/dl in group 1, +16 (+/- 91) μmol/l;+0.93(+/- 5.3) mg/dl in group 2 and -8 (+/- 76) μmol/l; -0.47 (+/- 4.4) mg/dl in group 3. These limits of agreement are too wide to be acceptable in a clinical setting. Moreover, there was to be a trend towards less good agreement with increasing bilirubin values.

Conclusion

Despite its new technology the Bilimed^® has no advantages, and more specifically no better agreement not only in term and near-term Caucasian infants, but also in non-Caucasian and more premature infants.