353 - Phototherapy minimally affects the correlation between total serum bilirubin and transcutaneous bilirubin levels in term and preterm infants

Poster Number: 353
Publication Number: 353.123

Meera N. Sankar, Stanford University, Palo Alto, CA, United States; Ganesh K. Sivakumar, Icahn School of Medicine at Mount Sinai, Sunnyvale, CA, United States; Dharshi Sivakumar, Stanford University School of Medicine, Sunnyvale, CA, United States; Melinda Porter, El Camino Health, Mountain View, CA, United States; Cody Arnold, Stanford University School of Medicine, Palo Alto, CA, United States; Ronald J. Wong, Stanford University School of Medicine, Stanford, CA, United States

Background: Transcutaneous bilirubin (TcB) measurements are safe, noninvasive, cost-effective, and widely used to screen late preterm and term infants for hyperbilirubinemia without the need for blood collection. However, there is paucity of data on the effect of phototherapy on TcB measurements in newborns.

Objective: To determine the effect of phototherapy on the correlation between TcB and total serum bilirubin (TSB) levels in term and preterm infants.

Design/Methods:
This retrospective study included all term and preterm infants admitted to a single center NICU in California. A TcB measurement was performed by trained nursing staff using the Draeger Jaundice Meter (JM-105) within 30-60 min of a paired routine TSB measurement during the first 2 weeks of life.  Neonates with TSB levels at the phototherapy threshold received treatment as per the standard protocol. The Bili Eclipse, a commercial photo-opaque patch, was placed on the area of skin on the sternum used to measure TcB in infants undergoing phototherapy. Differences between TcB and TSB values were compared by gestational age (GA) and on and off phototherapy. Correlation between TSB and TcB levels was assessed using Pearson’s correlation analyses. The Bland-Altman method was used to calculate the mean difference (or bias) and imprecision between TcB and TSB measurements.

Results: 440 paired TcB and TSB measurements from 154 infants were analyzed. Mean difference between TcB and TSB for all infants was 0.065+1.97. When stratified by GA, mean TcB/TSB differences were: -0.10+2.12 at >34wks (n=262) and -0.012+1.72 at < 34wks (n=178). During phototherapy, overall mean TcB/TSB differences were -0.45+2.68 (n=80), and -0.31+2.88 at >34wks (n=57) and -0.81+2.14 at < 34wks (n=23). Off phototherapy, overall mean TcB/TSB differences were -0.26±2.14 (n=63), and -0.76 ±2.49 (n=34) at >34wks and 0.31±1.48 at < 34wks (n=29) (Figure 1). Bland Altman analysis showed a good agreement at 95 percent limits during (Figure 2) and off phototherapy. Regression equation showed a moderate correlation during phototherapy (r2=0.66; TSB = 0.59 *TcB+4.02) and off phototherapy (r2=0.70; TSB = 0.72*TcB+3.27) compared with an r2=0.73 for all infants.Conclusion(s):
TcB levels correlated moderately with TSB values with or without phototherapy. We conclude that TcB measurements could be used to monitor TSB levels in infants during phototherapy and thus minimize invasive blood draws in the NICU setting.

Figure 1: Boxplot of TcB and TSB valuesBoxplot of TcB and TSB values by gestational age groups in infants on and off phototherapy
Figure 2: Bland- Altman plotBland-Altman plot with data showing the difference between TcB and TSB on the Y-axis against the mean of TcB and TSB on the X-axis during phototherapy