Trends in hospitalizations for neonatal jaundice and kernicterus in the United States, 1988-2005.

CONTEXT AND
OBJECTIVE: Recent reports have raised global concerns about a reemergence of kernicterus. Accurate information on the incidence of kernicterus is unavailable because of the rarity of the condition and the lack of a systematic surveillance strategy. We used nationally representative hospital discharge data to evaluate trends in the diagnosis and management of neonatal jaundice and the incidence of kernicterus in relation to the American Academy of Pediatrics hyperbilirubinemia clinical practice guideline. PATIENTS AND METHODS: The data came from the Healthcare Cost and Utilization Project family of databases. The Nationwide Inpatient Sample and the Kids' Inpatient Database were combined to generate trend data for the years 1988-2005. All neonatal discharges with primary or secondary International Classification of Diseases, Ninth Revision, Clinical Modification diagnoses codes for jaundice or kernicterus occurring within the first 30 days of life were selected with population incidence rates calculated from estimates of term and preterm newborn hospitalizations derived from the Healthcare Cost and Utilization Project data. To increase the reliability of identified kernicterus hospitalizations, newborns with a diagnosis of kernicterus and a procedure code for phototherapy or exchange transfusion were included as cases.
RESULTS: Hospital diagnosis codes for kernicterus likely included a substantial number of rule-out cases, because approximately 70% did not include a procedure code for phototherapy or exchange transfusion. Including only cases with a procedure code for phototherapy or exchange transfusion resulted in 2.7 per 100000 diagnosed with kernicterus over the entire study period. A diagnosis code for jaundice was recorded for 15.6% of newborns. The diagnosis of jaundice and kernicterus differed according to race and gender. Rates also were elevated in preterm relative to term infants for both jaundice and kernicterus. Trends in diagnosis for newborn jaundice were u-shaped, with rates falling in the years before the initial American Academy of Pediatrics guideline (1988-1993) and increasing in the years after publication of the guideline (1997-2005). In contrast, the number of newborn hospitalizations with a diagnosis of kernicterus generally declined throughout the study period. Most of the decline in hospitalizations for term infants with a diagnosis of kernicterus occurred before and immediately after publication of the 1994 guideline, going from 5.1 per 100000 in 1988 to 1.5 per 100000 in the years from 1994 to 1996 and has since remained constant.
CONCLUSIONS: Nationally representative hospital data indicate a declining incidence of hospitalizations with a diagnosis of kernicterus in newborn infants over the period 1988-2005. The decline occurred before and immediately after publication of the 1994 American Academy of Pediatrics guideline on hyperbilirubinemia. Epidemiologic findings were mostly consistent with other studies. Healthcare Cost and Utilization Project data provide an important system for monitoring hospitalizations of uncommon newborn conditions such as kernicterus.