Epidemiology of biliary atresia: A population-based study

Objective. Biliary atresia is the leading cause of extrahepatic obstructive jaundice in the newborn and is the single most frequent indication for liver transplantation in children. The cause of biliary atresia is unknown, although several mechanisms have been postulated to explain the inflammatory process that obliterates the bile ducts. Most interest has been directed toward viral infections, information about the epidemiologic characteristics of biliary atresia in well-defined populations is lacking but is essential for developing and addressing hypotheses of causation for the disease. Methods. Infants with biliary atresia were identified in metropolitan Atlanta from 1968 through 1993 by a population-based birth defects surveillance system that ascertains infants with serious birth defects in the first year of life using active case ascertainment. Birth prevalence rates were analyzed for spatial and temporal clustering and effects attributable to county of residence, sex, race, maternal age, parity, and birth weight. Logistic regression was used to study the independent effects of the risk factors and to look for interactions. Results. Fifty-seven infants with biliary atresia were identified, for a rate of 0.73 per 10 000 live births. There was significant seasonal clustering of the disease, with rates three times higher from December through March compared with rates from April through July. Rates were significantly higher among nonwhite infants compared with white infants (0.96 vs 0.44 per 10 000 live births) and infants born at term with low birth weights (<2500 g) compared with infants born at term with normal birth weights (greater than or equal to 2500 g) (2.62 vs 0.75 per 10 000 live births). Conclusions. Our study is the first in the United States to describe the epidemiologic characteristics of biliary atresia using a population-based approach. The demonstration of significant seasonal clustering provides support for theories that biliary atresia may be caused by environmental exposure (consistent with a viral cause) during the perinatal period.