Agreement test of transcutaneous bilirubin and bilistick with serum bilirubin in preterm infants receiving phototherapy

Background: This study compares the minimally invasive Bilistick and a noninvasive method with standard Total Serum Bilirubin (TSB) measurement in preterm newborns receiving phototherapy. We assess the agreement of Transcutaneous Bilirubinometer (TcB) and Bilistick bilirubin measurements with standard TSB measurement in preterm infants receiving phototherapy. Methods: Bilirubin was measured by using TcB and Bilistick in 94 preterm infants in RSCM Jakarta Neonatal Ward from October 2016 to March 2017, with gestational ages of < 35 weeks, before phototherapy and after 24 and 48 h of phototherapy. Results: There was significant correlation before, at 24 and 48 h of phototherapy between TSB and either TcB (r = 0.874; r = 0.889; r = 0.878 respectively; p < 0.0001), or Bilistick (r = 0.868; r = 0.877; r = 0.918 respectively; p < 0.0001). The mean difference and limits of agreement before, at 24 and 48 h of phototherapy between TcB and TSB were 0.81 +/- 1.51 mg/dL (-2.14 to 3.77 mg/dL); 0.43 +/- 1.57 mg/dL (-2.66 to 3.51 mg/dL); 0.41 +/- 1.58 mg/dL (-2.69 to 3.50 mg/dL), respectively. For Bilistick they were -1.50 +/- 1.47 mg/dL (-4.38 to 1.38 mg/dL); -1.43 +/- 1.47 mg/dL (-4.32 to 1.46 mg/dL); -1,15 +/- 1.31 mg/dL (-3,72 to 1,42 mg/dL), respectively. Conclusions: Both methods are reliable for measuring TSB before, during, and after phototherapy in preterm infants. TcB tends to overestimate while Bilistick underestimates TSB.