Validity of transcutaneous bilirubin measurements during and after phototherapy in term and late preterm infants

Abstract

The purpose of the study was to investigate correlation and concordance between total serum bilirubin (TSB) and transcutaneous bilirubin measured at covered (TcBC) and uncovered (TcBU) skin during and after discontinuation of phototherapy. A cross-sectional study included ≥ 34 weeks gestation infants requiring phototherapy for neonatal hyperbilirubinemia. In-house, photo-opaque patches were placed on infants’ sternums before phototherapy initiation. Simultaneous blood sampling for TSB, TcBC, and TcBU measurements were performed. Among 103 infants included in the final analysis, 70% were full-term. Covering skin during phototherapy resulted in strong TcBC-TSB correlation (r = 0.91, 95% CI 0.87–0.94, P < 0.001) compared to TcBU (r = 0.53, 95% CI 0.37–0.65, P < 0.001), persisting post-phototherapy (r = 0.88, 95% CI 0.82–0.91, P < 0.001). Bland–Altman analysis showed a higher mean difference and wider 95% limits of agreement for TcBU-TSB during phototherapy (-6.3 mg/dL and -11.1 to -1.6) vs TcBC-TSB (0.9 mg/dL and -1.2 to 2.9). Passing-Bablok regression analysis confirmed good agreement between TcBC and TSB. Conclusions: The application of in-house, photo-opaque patches enhanced the correlation and agreement between TcBC and TSB during and after discontinuation of phototherapy. This may prove particularly useful in resource-limited settings where commercial devices are unavailable. (Table presented.)