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Fractionated Bilirubin Among 252 892 Utah Newborns with and Without Biliary Atresia: A 15-year Historical Birth
Zachary J Kastenberg1, Mark R Deneau2, Elizabeth A O'Brien3
1Division of Pediatric Surgery, Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT.
Insights
Elevated conjugated or direct bilirubin levels in newborns can indicate biliary atresia (BA). A higher screening threshold improves detection accuracy for this serious liver condition in infants.
Area of Science:
- Neonatal Medicine
- Pediatric Gastroenterology
- Public Health Screening
Background:
- Biliary atresia (BA) is a rare but serious neonatal liver disease requiring early diagnosis and intervention.
- Elevated conjugated or direct bilirubin levels in newborns are key indicators that warrant further investigation for potential liver issues.
- Current screening methods may generate false positives, necessitating refined diagnostic thresholds.
Purpose of the Study:
- To ascertain if neonatal conjugated or direct bilirubin levels are elevated in infants diagnosed with biliary atresia (BA).
- To estimate the number of newborns who might screen positive, requiring follow-up testing.
- To evaluate the impact of adjusted bilirubin thresholds on screening performance.
Main Methods:
- Utilized administrative data from a large healthcare network (2005-2019) to identify newborns with fractionated bilirubin measurements.
- Defined elevated conjugated bilirubin (>0.2 mg/dL) and direct bilirubin (>0.5 mg/dL) based on laboratory percentiles.
- Conducted simulations to predict false-positive screen rates at different threshold levels.
Main Results:
- Out of 252,892 newborns assessed, 26 had BA. All 26 infants with BA exhibited elevated conjugated or direct bilirubin.
- An additional 3,246 newborns (1.3%) without BA also had elevated levels.
- Simulations indicated 9-21 per 1000 screened infants could have elevated bilirubin; higher thresholds improved screening accuracy without increasing false negatives.
Conclusions:
- Confirms that elevated conjugated or direct bilirubin is a consistent finding in newborns with BA.
- Implementing a higher threshold for conjugated bilirubin enhances screening performance for BA.
- Further research is needed to optimize BA screening tests and evaluate program effectiveness and cost-efficiency.
Objectives:
To determine whether neonatal conjugated or direct bilirubin levels were elevated in infants with biliary atresia (BA) and to estimate the number of newborns who would have positive screens in the nursery necessitating repeat testing after discharge.
Study Design:
We used administrative data from a large integrated healthcare network in Utah to identify newborns who had a fractionated bilirubin recorded during birth admission from 2005 through 2019. Elevated conjugated bilirubin was defined as greater than 0.2 mg/dL and direct bilirubin was defined as greater than 0.5 mg/dL (>97.5th percentile for the assays). We performed simulations to estimate the anticipated number of false-positive screens.
Results:
There were 32 cases of BA and 468 161 live births during the study period (1/14 700). There were 252 892 newborns with fractionated bilirubin assessed, including 26 of those subsequently confirmed to have BA. Conjugated or direct bilirubin was elevated in all 26 infants with BA and an additional 3246 newborns (1.3%) without BA. Simulated data suggest 9-21 per 1000 screened newborns will have an elevated conjugated or direct bilirubin using laboratory-based thresholds for a positive screen. Screening characteristics improved with higher thresholds without increasing false-negative tests.
Conclusions:
This study validates the previous findings that conjugated or direct bilirubin are elevated in the newborn period in patients with BA. A higher threshold for conjugated bilirubin improved screening performance. Future studies are warranted to determine the optimal screening test for BA and to assess the effectiveness and cost-effectiveness of implementing such a program.
