Transcutaneous bilirubinometry is a widely used screening method for neonatal hyperbilirubinemia. Deviation of the transcutaneous bilirubin concentration (TcB) from the total serum bilirubin concentration (TSB) is often ascribed to biological variation between patients, but variations between TcB meters may also have a role. This study aims to provide a systematic evaluation of the inter-device reproducibility of TcB meters.
Thirteen commercially available TcB meters (JM-105 and JM-103) were evaluated in vitro on phantoms that optically mimic neonatal skin. The mimicked TcB was varied within the clinical range (0.5-181.3 μmol/L).
Absolute differences between TcB meter outcomes increased with the measured TcB, from a difference of 5.0 μmol/L (TcB = 0.5 μmol/L phantom) up to 65.0 μmol/L (TcB = 181.3 μmol/L phantom).
The inter-device reproducibility of the examined TcB meters is substantial and exceeds the specified accuracy of the device (±25.5 μmol/L), as well as the clinically used TcB safety margins (>50 µmol/L below phototherapy threshold). Healthcare providers should be well aware of this additional uncertainty in the TcB determination, especially when multiple TcB meters are employed in the same clinic. We strongly advise using a single TcB meter per patient to evaluate the TcB over time.
Key message: The inter-device reproducibility of TcB meters is substantial and exceeds the clinically used TcB safety margins.What this study adds to existing literature: The inter-device reproducibility of transcutaneous bilirubin (TcB) meters has not been reported in the existing literature. This in vitro study systematically evaluates this inter-device reproducibility.
This study aids in a better interpretation of the measured TcB value from a patient and is of particular importance during patient monitoring when using multiple TcB meters within the same clinical department. We strongly advise using a single TcB meter per patient to evaluate the TcB over time.Fig. 1a Schematic overview of the working principle of the evaluated TcB meters (JM-103 and JM-105). Both types of meters have the same optical design. b Photograph of the tip of the evaluated TcB meter with light being emitted from the illumination ring (pink). The detection rings for the long and short optical path appear as dark gray in the photograph.Fig. 2Measured TcB values per TcB meter (M1-M13, Table 1) and phantom (F1-F6, Table 2) as a function of a the absorption coefficient of the phantom at 450 nm, and b the average measured TcB over all meters. Error bars (standard deviation of the TcB measurements per meter) fall behind the data points.Fig. 3Intra-device reproducibility (average SD over all measurements and phantoms per TcB meter) as a function of time since installation in the clinic (i.e., TcB meter age). The correlation coefficient between both parameters is R = 0.03. Error bars represent the standard deviation of the average SD across phantoms.