Supplementary Material for: Assessing diagnostic accuracy of a handheld point-of-care device for quantifying neonatal bilirubin levels: the BEAT jaundice @home study

Introduction The Bilistick is a handheld point-of-care device for measuring total bilirubin levels in small blood volumes. We assessed its diagnostic accuracy and user convenience in near-term neonates cared for at home. Methods A prospective cohort study was conducted in nine Dutch community midwifery practices. Neonates ≥35 weeks' gestation were eligible if they were at home between postnatal days 2–8 and had not received phototherapy. A Bilistick version 2.0 was used in parallel to laboratory-based bilirubin (LBB) quantification when significant visible jaundice was observed or the transcutaneous bilirubin reading was elevated. Results 2314 neonates were included in the study, with 423 blood samples analyzed across 13 laboratories. On 203 occasions, the Bilistick was not used. Among the remaining 220 Bilistick readings, 104 failed, and two lacked corresponding LBB results. A Bland-Altman plot of 114 paired measurements of Bilistick and LBB showed a mean difference of +9.7 µmol/L (0.57 mg/dL) with corresponding 95% limits of agreement of -179.7 to +199.2 µmol/L (-10.5 to 11.7 mg/dL). The positive predictive value of a Bilistick reading for having a TSB level above the phototherapy threshold was 36.4%. The negative predictive value was 90.1%, sensitivity 60% and specificity 77.6%. Hemolysis (24%) contributed to overestimations by the Bilistick. Community midwives expressed multiple barriers related to user convenience. Conclusion Diagnostic accuracy of the Bilistick when used in the home setting was limited. Its use was further hindered by a significant proportion of failed readings and low user-convenience when operated by midwives.