Frequency of Neonatal Bilirubin Testing and Hyperbilirubinemia in a Large Health Maintenance Organization

Abstract

Objective. To determine the frequency and interhospital variation of bilirubin testing and identified hyperbilirubinemia in a large health maintenance organization. Design. Retrospective cohort study. Setting. Eleven Northern California Kaiser Permanente hospitals. Subjects. A total of 51 387 infants born in 1995–1996 at ≥36 weeks' gestation and ≥2000 g. Main Outcome Measure. Bilirubin tests and maximum bilirubin levels recorded in the first month after birth. Results. The proportion of infants receiving ≥1 bilirubin test varied across hospitals from 17% to 52%. The frequency of bilirubin levels ≥20 mg/dL (342 μmol/L) varied from .9% to 3.4% (mean: 2.0%), but was not associated with the frequency of bilirubin testing (R2 = .02). Maximum bilirubin levels ≥25 mg/dL (428 μmol/L) were identified in .15% of infants and levels ≥30 mg/dL (513 μmol/L) in .01%. Conclusions. Significant interhospital differences exist in bilirubin testing and frequency of identified hyperbilirubinemia. Bilirubin levels ≥20 mg/dL were commonly identified, but levels ≥25 mg/dL were not.