Objectives AAP supported the development of bilirubin nomograms in different populations to better evaluate the jaundice in various settings. Skin bilirubin determination is becoming widespread. We recently published the European skin bilirubin nomogram and now 4 curves are available. This suggests the existence of wide differences in the bilirubin trend and kinetics. We aimed to review such differences using metaanalysis tools to obtain normative data on skin bilirubin kinetics.
Methods Metaanalysis of the raw dataset provided by single Authors. Comparison with AAP recommendations. Velocity/acceleration analysis and plotting their supposed trend overtime, using advanced non-linear regression. Definition of risk value for skin bilirubin rate of increase.
Results Studies show significant differences about populations and mean bilirubin value. Significant variability exists in the velocity and trends: mean weighted bilirubin and velocity are provided from metanalysis. Hyspanic babies show the higher velocity and the more late plateau: both Hyspanic and European may need phototherapy even when bilirubin is <95th percentile. Weighted velocity reach a plateau close to 0 at ≈96 h, in fact acceleration is highly positive before 48 h, become negative and then approaches to 0, after 48 h. Velocity and acceleration are significantly described by quadratic relationship. Rates needed to cross the curves decrease overtime but in the first 48 h are lower than usually reported (>0.11 mg/dl/h).
Conclusions Use of different nomograms may influence the evaluation of jaundice. Clinicians must choose the curve most similar to their population. In the first 48 h, velocity >0.11 mg/dl/h may lead to bilirubin rise over the initial percentile.