Noninvasive measurement of total serum bilirubin in a multiracial predischarge newborn population to assess the risk of severe hyperbilirubinemia

Background. Jaundice in near-term and term newborns is a frequent diagnosis that may prompt hospital readmission in the first postnatal week. Hyperbil irubinemia, when excessive, can lead to potentially irreversible bilirubin- induced neurotoxicity. Predischarge risk assessment (at 24-72 hours of age) for subsequent excessive hyperbilirubinemia is feasible by a laboratory-ba sed assay of total serum bilirubin (TSB). Hypothesis. Noninvasive, transcutaneous, point-of-care measurement of trans cutaneous bilirubin (TcB) predischarge by multiwavelength spectral analysis , using a portable BiliCheck device (SpectRx Inc, Norcross, GA), is clinica lly equivalent to measurement of TSB in a diverse, multiracial term and nea r-term newborn population and predictive of subsequent hyperbilirubinemia. Methodology. We evaluated a hand-held device that uses multiwavelength spec tral reflectance analysis to measure TcB (BiliCheck). The study population (490 term and near-term newborns) was racially diverse (59.1% white, 29.5% black, 3.46% Hispanic, 4.48% Asian, and 3.46% other) and was evaluated at 2 separate institutions using multiple (11) devices. The postnatal age range d from 12 to 98 hours and the ranges of birth weights and gestational ages were 2000 to 5665 g and 35 to 42 weeks, respectively. All transcutaneous ev aluations were performed contemporaneously and paired with a heelstick TSB measurement. All TSB assays were performed by high performance liquid chrom atography, as well as by diazo dichlorophenyldiazonium tetrafluoroborate te chniques. Results. TSB values ranged from .2 to 18.2 mg/dL (mean +/- standard deviati on: 7.65 +/- 3.35 mg/dL). The overall correlation of TSB (by high performan ce liquid chromatography technique) to TcB (by BiliCheck devices) was linea r and statistically significant (r = .91; r(2) = .83; TcB = .84; TSB = .75; standard error of regression line = 1.38; P < .001; n = 490 infants; 1788 samples). Similar regression statistics were evident in subset populations categorized by race (white: r = .91 [n = 289 infants]; black: r = .91 [n = 145 infants]) as well as by gestation (term: r = .91 [n = 1625 samples]; ne ar-term: r = .89 [n = 163 samples]). Intradevice precision was determined t o be .59 mg/dL (2-3 measurements per infant with 1 device; n = 210 infants; 510 samples in a separate subset). Interdevice evaluation of 11 devices de termined the precision to be .68 mg/dL (2-4 devices used for measurements p er patient). In 23 of 419 of the study population infants who were in the 24- to 72-hour age range, the predischarge TSB values designated them to be at high risk for subsequent excessive hyperbilirubinemia (above the 95th percentile trac k on the hour-specific bilirubin nomogram). For these infants, the paired B iliCheck TcB values were all above the 75th percentile track (negative pred ictive value = 100%; positive predictive value = 32.86%; sensitivity = 100% ; specificity = 88.1%; likelihood ratio = 8.43). Conclusions. Our data demonstrate the accuracy and reproducibility of the p redischarge BiliCheck measurements in term and near-term newborn infants of diverse races and ethnicities. Infants with predischarge BiliCheck values above the 75th percentile of hour-specific TSB values on the bilirubin nomo gram may be considered to be at high risk for subsequent excessive hyperbil irubinemia. Further studies are needed to assess the efficacy of this techn ique in preterm infants, those undergoing phototherapy, and those with TSB values of greater than or equal to 15 mg/dL (greater than or equal to 256 m u mol/L).