Nomogram can help estimate risk of serious hyperbilirubinemia in healthy infants
Article Outline
- Question
- Design
- Setting
- Participants
- Intervention
- Outcomes
- Main Results
- Conclusions
- Commentary
- References
- Copyright
Varvarigou A, Fouzas S, Skylogianni E, Mantagou L, Bougioukou D, Mantagos S. Transcutaneous bilirubin nomogram for prediction of significant neonatal hyperbilirubinemia. Pediatrics 2009;124:1052-9.
Question
In healthy term and near-term neonates, can transcutaneous bilirubin (TcB) measurements be used to develop a predictive nomogram to assess the risk of significant hyperbilirubinemia?
Design
Prospective cohort.
Setting
Well-infant nursery in a university hospital in Greece, between September 2005 and December 2007.
Participants
2039 healthy neonates (gestational age ≥35 weeks and birth weight ≥2000 g).
Intervention
10 382 TcB measurements were performed with a BiliCheck bilirubinometer (SpectRx, Norcross, GA) at designated time points between 12 and 120 hours of life.
Outcomes
Significant hyperbilirubinemia was defined on the basis of the hour-specific threshold values for phototherapy proposed by the American Academy of Pediatrics.
Main Results
Using likelihood ratios (LRs), the high- and low-risk demarcators for each designated time were calculated and presented on an hour-specific nomogram. Significant hyperbilirubinemia was documented for 122 neonates (6%). At 24 hours of life, the high-risk zone of the nomogram had 73.9% sensitivity and a positive LR of 12.1 in predicting significant hyperbilirubinemia, whereas the low-risk zone had 97.7% sensitivity and a negative LR of 0.04. At 48 hours, the high-risk zone had 90% sensitivity and a positive LR of 12.1, whereas the low-risk zone had 98.8% sensitivity and a negative LR of 0.02. In this study population, the probability of significant hyperbilirubinemia would be >35% for values in the high-risk zone and <0.5% for values in the low-risk zone of the nomogram.
Conclusions
The authors provide a predictive TcB tool that could allow for a noninvasive, risk-based approach to neonatal hyperbilirubinemia.
Commentary
This paper presents nomograms for interpreting hour-specific transcutaneous bilirubin (TcB) measurements with the Bilicheck device, by predicting whether infants should receive phototherapy according to the American Academy of Pediatrics (AAP) guidelines.1 The authors' approach appears to be a pragmatic one—pediatricians will have to act on the basis of TcB measurements, and, presumably, they intend to follow the AAP guidelines. Briefly, the AAP guidelines interpret total serum bilirubin (TSB) measurements differently for infants in “low,” “intermediate,” and “high” baseline risk strata that are defined by gestational ages and risk factor profiles. Yet, the Varvarigou nomogram explicitly averages over the baseline risk strata. I do not argue that this is a bad decision—I merely point out the oddity of predicting a combination of TSB and clinical factors from a surrogate of TSB alone. So, to which baseline risk stratum is the Varvarigou nomogram “high-risk zone” cutoff most applicable? Judging from the distribution of gestational ages (infants with risk factors were practically excluded), 20% of the studied infants are of “intermediate” baseline risk with the rest being “low” risk. Therefore, the Varvarigou “high-risk zone” boundary is a bit of an underestimate for “low risk,” a bit of an overestimate for “intermediate risk,” and an overestimate for (the excluded) “high-risk” infants in the AAP guidelines. It is my own belief that we can only fully understand the implications of variations in screening through careful decision modeling.2 The authors have a wonderful data set to model the TcB trajectories of individual infants over time and the opportunity to pursue more detailed models than those published to date. It may be worth a try.
References
PII: S0022-3476(09)01203-7
doi:10.1016/j.jpeds.2009.11.068
© 2010 Mosby, Inc. All rights reserved.
