Frequency of neonatal bilirubin testing and hyperbilirubinemia in a large health maintenance organization

Objective. To determine the frequency and interhospital variation of biliru bin 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 greater than or eq ual to 36 weeks' gestation and greater than or equal to 2000 g. Main Outcome Measure. Bilirubin tests and maximum bilirubin levels recorded in the first month after birth. Results. The proportion of infants receiving greater than or equal to 1 bil irubin test varied across hospitals from 17% to 52%. The frequency of bilir ubin levels greater than or equal to 20 mg/dL (342 mu mol/L) varied from .9 % to 3.4% (mean: 2.0%), but was not associated with the frequency of biliru bin testing (R-2 = .02). Maximum bilirubin levels greater than or equal to 25 mg/dL (428 mu mol/L) were identified in .15% of infants and levels great er than or equal to 30 mg/dL (513 mu mol/L) in .01%. Conclusions. Significant interhospital differences exist in bilirubin testi ng and frequency of identified hyperbilirubinemia. Bilirubin levels greater than or equal to 20 mg/dL were commonly identified, but levels greater tha n or equal to 25 mg/dL were not.