968 Estimation of hemolytic disease of the newborn in the United States from 1996-2010

Abstract

Hemolytic Disease of the Newborn (HDN) or Fetus and Newborn (HDFN) has not been assessed over years at the national level in the United States (US) since the 1980’s when the incidence of Rh HDN was estimated to be 106/100,000 births based on the CDC’s Birth Defects Monitoring Program. Current estimates of 3-80/100,000 for Rh HDFN and 30-700/100,000 for ABO HDFN are derived from indirect data sources. We utilized a nationally representative medical care survey, the National Hospital Discharge Survey to estimate the rate of HDN in neonates in the US from 1996 to 2010. Data were collected from neonates with ICD-9 codes 773.0-773.5, indicating HDN caused by Rh, ABO and other/unknown red cell antigens. Rates of neonatal HDN, demographics, and outcomes were analyzed over the 15-year timeframe and compared to those of non-HDN newborns. Severe HDN was defined as neonates requiring exchange transfusion or IVIg or suffering hydrops, late onset of anemia or death. Weighted frequencies and Chi Square analyses (SAS v9.4) were utilized. A total of 480,230 births were included in the analysis. The rate of all HDN remained stable at 1,700 cases/100,000 newborns whereas Rh HDN declined, on average, from 85 to 60 cases per 100,000 newborns. The majority of HDN was caused by ABO incompatibility or other/unknown antigens. While white newborns formed the majority of HDN cases, the rate of HDN was observed to be higher amongst black (2.3%) versus white (1.6%) neonates. Compared to healthy newborns, HDN newborns experienced longer hospital stays (3 days vs 2 days), were less likely to be routinely discharged (97.99% vs 99.72%) and had higher Caesarean section rates (30.6% vs 20.9%). Severe HDN occurred in 5.8-7.5/100,000 newborns. Using a nationally representative database, the estimated rate of HDN is consistent with those observed in previous studies. Despite RhIg prophylaxis, a low rate of Rh HDN persists as does severe disease and the need for increased neonatal care. Demographic and clinical disparities merit further investigation.