How accurate is transcutaneous bilirubin testing in newborns with darker skin tones?
EVIDENCE-BASED ANSWER:
Fairly accurate. Photometric transcutaneous bilirubin (TcB) testing may overestimate total serum bilirubin (TSB) in neonates with darker skin tones by a mean of 0.68 to > 2 mg/dL (strength of recommendation [SOR]: C, diagnostic cohort studies with differing reference standards).
Overall, TcB meters retain acceptable accuracy in infants of all skin tones across a range of bilirubin levels, despite being more likely to underestimate lighter skin tones and overestimate darker ones (SOR: C, diagnostic cohort studies with differing reference standards). It is unclear if the higher readings prompt an increase in blood draws or otherwise alter care.
Stated limitations of the study included relatively low numbers of neonates with dark skin tone, no test of interobserver reliability in skin tone assignment, and enrollment of exclusively healthy neonates with low bilirubin levels.2
Other studies report overestimation in infants with darker skin tone
Two Canadian diagnostic cohort studies also found evidence that TcB testing overestimated TSB in infants with darker skin tones, although TcB test characteristics proved stable over a wide range of bilirubin levels.
The first study enrolled 451 neonates ≥ 35 weeks gestational age at a hospital in Ottawa and assessed TcB using the JM-103 meter.3 The neonates were stratified into light (n = 51), medium (n = 326), and dark (n = 74) skin tones using cosmetic reference color swatches. All had a TcB and TSB obtained within 30 minutes of each other.
TcB testing underestimated TSB in infants with light and medium skin tones and overestimated TSB in infants with darker skin tone (mean difference, –0.88 mg/dL for light; –1.1 mg/dL for medium; and 0.68 mg/dL for dark; P not given). The mean area under the curve (AUC) was ≥ 0.94 for all receiver–operator characteristic (ROC) curves across all skin tones and bilirubin thresholds (AUC range, 0-1, with > 0.8 indicating strong modeling).3
Limitations of the study included failure to check interrater reliability for skin tone assessment, low numbers of infants with elevated bilirubin (≥ 13.5 mg/dL), and very few infants in either the dark or light skin tone groups.3
Continue to: The second Canadian study...
