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

Abstract

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) micromol/l; -0.82 (+/- 8.4) mg/dl in group 1, +16 (+/- 91) micromol/l;+0.93(+/- 5.3) mg/dl in group 2 and -8 (+/- 76) micromol/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.

Figures

Figure 1

Bilimed® values on the sternum against total serum bilirubin values in term infants (Figure 1A, group 1, n = 111) and in preterm infants (Figure 1B, group 2 and 3, n = 68). Continuous linear regression line; dotted line of identity.

Figure 2

Bilimed® values on the sternum against total serum bilirubin values in Caucasian (Figure 2A, n = 126) and non-caucasian (Figure 2B, n = 59). Continuous linear regression line; dotted line of identity.

Figure 3

Bland-Altman plot showing agreement between total serum bilirubin values and the Bilimed® values for group 1. The lines represent mean difference (-14) and ± 2SD of the difference (+/- 144)

Figure 4

Bland-Altman plot showing agreement between total serum bilirubin values and the Bilimed® values for group 2. The lines represent mean difference (+16) and ± 2SD of the difference (+/- 91)

Figure 5

Bland-Altman plot showing agreement between total serum bilirubin values and the Bilimed® values for group 3. The lines represent mean difference (-8) and ± 2SD of the difference (+/- 76)

Figure 6

Bland-Altman plot showing agreement between total serum bilirubin values and the Bilimed® values for Caucasian (white rectangles, dotted lines indicate mean (16) and ± 2SD of the difference (+/- 121) and for non-caucasian (black diamonds, continuous lines represent mean (10) and ± 2SD of the difference (+/- 174).