Laboratory validation and field usability assessment of a point-of-care test for serum bilirubin levels in neonates in a tropical setting

Diagnostic methods for neonatal hyperbilirubinemia: benefits, limitations, requirements, and novel developments

Invasive bilirubin measurements remain the gold standard for the diagnosis and treatment of infants with severe neonatal hyperbilirubinemia. The present paper describes different methods currently available to assess hyperbilirubinemia in newborn infants. Novel point-of-care bilirubin measurement methods, such as the BiliSpec and the Bilistick, would benefit many newborn infants, especially in low-income and middle-income countries where the access to costly multi-analyzer in vitro diagnostic instruments is limited. Total serum bilirubin test results should be accurate within permissible limits of measurement uncertainty to be fit for clinical purposes. This implies correct implementation of internationally endorsed reference measurement systems as well as participation in external quality assessment programs. Novel analytic methods may, apart from bilirubin, include the determination of bilirubin photoisomers and bilirubin oxidation products in blood and even in other biological matrices. IMPACT: Key message: Bilirubin measurements in blood remain the gold standard for diagnosis and treatment of severe neonatal hyperbilirubinemia (SNH). External quality assessment (EQA) plays an important role in revealing inaccuracies in diagnostic bilirubin measurements. What does this article add to the existing literature? We provide analytic performance data on total serum bilirubin (TSB) as measured during recent EQA surveys. We review novel diagnostic point-of-care (POC) bilirubin measurement methods and analytic methods for determining bilirubin levels in biological matrices other than blood. Impact: Manufacturers should make TSB test results traceable to the internationally endorsed total bilirubin reference measurement system and should ensure permissible limits of measurement uncertainty.

Diagnostic Properties of a Portable Point-of-Care Method to Measure Bilirubin and a Transcutaneous Bilirubinometer

BACKGROUND

Recently, the Bilistick®, a point-of-care instrument to measure bilirubin levels, has been developed. It is fast and cheaper than transcutaneous bilirubin (TCB)-measuring devices, but data on diagnostic properties are scarce.

OBJECTIVE

This study aimed to compare the performance of the Bilistick® (BM-BS 1.0 - FW version 2.0.1) and the JM-105 bilirubinometer for measuring bilirubin.

METHOD

This is a prospective study in infants born after ≥32 weeks' gestation, and/or a birth weight of ≥1,500 g, and a postnatal age ≤14 days in Surabaya, Indonesia. Bilirubin was measured with the Bilistick® System (BM-BS 1.0 - FW version 2.0.1), transcutaneously (TCB) with the JM-105 bilirubinometer, and in serum (TSB) with a routine laboratory technique. Mean differences and 95% limits of agreement (LOA) and correlations were calculated.

RESULT

We enrolled 149 neonates and 126 had paired measurements of Bilistick® bilirubin, TCB, and TSB. Bilistick® failed in 16 (10.7%) infants. Mean Bilistick® bilirubin-TSB difference was -11 µmol/L (95% LOA: -101 to 79 µmol/L) and r = 0.738 (p < 0.001). Mean TCB-TSB difference was 26 μmol/L (95% LOA: -33 to 88) and r = 0.785 (p < 0.001). The sensitivity, specificity, PPV, and NPV for Bilistick® bilirubin for a TSB above treatment thresholds were 0.74, 0.84, 0.67, and 0.88, respectively, and for TCB 0.92, 0.64, 0.54, and 0.95, respectively.

CONCLUSION

The Bilistick® System (BM-BS 1.0 - FW version 2.0.1) underestimates TSB, whereas TCB overestimates TSB in jaundiced Indonesian infants. Further improvement of Bilistick®'s diagnostic accuracy with less false-negative readings is essential to increase its use.