New Model May Simplify Hyperbilirubinemia Risk Estimation

By Reuters Staff

April 29, 2021

NEW YORK (Reuters Health) - Researchers have developed a more precise and simpler method to determine when a newborn requires outpatient follow-up for jaundice.

Their method had "excellent ability to predict postdischarge total serum bilirubin (TSB) above phototherapy thresholds and may be simpler to use than the Bhutani Nomogram," Dr. Michael Kuzniewicz, with Kaiser Permanente Division of Research in Oakland, California, and colleagues report in Pediatrics.

Jaundice impacts more than half of term and late-preterm newborns in the first week of life. The American Academy of Pediatrics (AAP) recommends using a graph of predischarge TSB levels by age (the Bhutani Nomogram) to help guide newborn follow-up and a separate graph to determine if an infant meets a threshold for phototherapy.

Dr. Kuzniewicz and colleagues found that using a single graph that incorporates the difference between the last TSB before discharge and the AAP phototherapy threshold (the delta-TSB model) improves the prediction of a postdischarge TSB above the phototherapy threshold.

They compared three models - delta-TSB, delta-TSB-Plus, which includes additional variables, and the Bhutani Nomogram - in an ethnically diverse sample of more than 148,000 newborns born at 35 weeks' gestation or more.

Follow-up TSB testing was performed in 40% of infants. A total of 2,623 (1.8%) newborns exceeded the AAP phototherapy threshold after discharge.

The predicted probability of exceeding the phototherapy threshold after discharge ranged from 56% for a predischarge delta-TSB 0 to 1 mg/dL below the threshold to 0.008% for delta-TSB more than 7 mg/dL below the threshold, the authors report.

They found that discrimination was better for the delta-TSB model (area under the receiver operating characteristic curve, 0.93) and the delta-TSB-Plus model (AUC, 0.95) than for the Bhutani Nomogram (AUC, 0.88).

The authors of a linked editorial note that while all three models performed well for babies at the highest and lowest risk of developing severe hyperbilirubinemia, "both (delta-TSB and delta-TSB-Plus) models differentiated newborns in the intermediate zones better than the Bhutani Nomogram."

Dr. Laura Kair of the University of California, Davis, and Dr. Carrie Phillipi of Oregon Health and Science University, in Portland, also point out that 44% of newborns in Bhutani's high-intermediate risk zone - who would be recommended for follow-up within 48 hours - had a delta-TSB between 24 and 25 mg/dL.

"In these newborns, the risk of ever having a subsequent TSB measurement above the AAP threshold was only 1.6%, suggesting follow-up within 48 hours might not be indicated," they note.

Dr. Kair and Dr. Phillipi say it's important to consider that the delta-TSB measurements used in this study relied on clinician discretion in follow-up; "therefore, the predictive accuracy of the (delta-TSB) models may be inflated because of differential verification bias as the authors mention."

This study, they say, "could have significant impact on the experience of care for new families and curb health care overuse. Implementation of a (delta-TSB) approach has the potential to simplify postdischarge phototherapy risk estimation and might decrease unnecessary health care visits and extra hospital days for newborns previously stratified to the high- intermediate and low-intermediate risk zones on the Bhutani Nomogram."

"Select newborns could be discharged at 24 hours rather than 48 hours given this new evidence supporting an enhanced understanding of bilirubin trajectories. Some newborns with intermediate risk could safely defer in-person follow-up through weekends, holidays, and inclement weather days, whereas others may avoid daily outpatient bilirubin sampling with more optimally timed follow-up," Drs. Kair and Phillipi add.

"This research also highlights, with large numbers, how truly low risk some newborns are for developing significant hyperbilirubinemia. With increasing adoption of telemedicine, those newborns who are also at low risk of feeding problems could be safely cared for in their homes," they conclude.

The study had no commercial funding and authors have no relevant disclosures.

SOURCE: Pediatrics, online April 26, 2021.