The geoepidemiology of primary biliary cirrhosis: Contrasts and comparisons with the spectrum of autoimmune diseases

Recent data have suggested that the prevalence of many autoimmune diseases is higher than originally suspected. Indeed, the incidence of some autoimmu ne diseases may be increasing. Part of the problem in these later two issue s is that thee is a dearth of well-designed and controlled epidemiologic st udies, and often confounding variables in diverse populations and geographi c areas that are not well controlled. Primary biliary cirrhosis (PBC) is a highly directed, organ-specific autoimmune disease that results in the dest ruction of intrahepatic bile ducts. It is primarily a disease of middle-age d women. Although there is no obvious association with MHC class I or class II alleles, the relative risk of a family member of a first-degree relativ e within a family having a member with PBC is a hundred-fold that of the ge neral population. Unfortunately, most epidemiologic studies have been descr iptive, providing incidence and prevalence rates with many methodologic pro blems, including lack of an appropriate case definition, varying criteria f or inclusion of cases, and inaccurate estimate of the time period to which the rate applies. Because PBC is a ver definable disease with significant c linical and serologic overlaps among patients throughout the world, we beli eve that a review of the geoepidemiology of PBC is not only specifically of value to workers interested in autoimmune liver disease, but also of gener ic interest in the study of autoimmune disease. In this review, we discuss the nature of the existing epidemiologic data and the possible roles of gen etic and environmental factors in the etiology of the disease and compare s uch data to similar observations for multiple sclerosis, systemic lupus ery thematosus, and rheumatoid arthritis. (C) 1999 Academic Press.