Worldwide Incidence of Autoimmune Liver Disease.

BACKGROUND

The variation that occurs in the incidence patterns of autoimmune liver diseases may provide insight into the risk factors causing the diseases. We systematically reviewed studies on the incidence of autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), and immunoglobulin G4-associated cholangitis (IAC) in general populations.

KEY MESSAGES

We found relevant studies through Medline and Scopus, and we examined whether they were population-based; the way they found cases for inclusion and which diagnostic criteria they used; and whether they used standardization to facilitate comparison with other studies. The 55 identified studies varied greatly in their case-finding methods, and only 14 (25%) of them used a standard population. Reported incidence rates of AIH were around 1 per 100,000 population per year, possibly higher in Scandinavia than in other countries, and a Danish study of the 1994-2012 period found an increasing incidence. A majority of PBC studies found incidence rates of 1-2 per 100,000 population per year and an increasing time trend, but incidence was lower in the Netherlands and New Zealand and higher in North East England. Most studies of PSC found incidence rates around 1 per 100,000 population per year, but there were no incident cases among 100,000 Alaska natives during the period 1984-2000. The incidence of IAC remains unknown.

CONCLUSIONS

The incidence of the autoimmune liver diseases is around 1-2 per 100,000 population per year for each disease. The variation in incidence over time and place suggests that there are differences in the prevalence of risk factors for the diseases, but the studies used different methods and so it is difficult to draw firm conclusions. We recommend that groups of investigators conduct multisite studies with identical case-finding methods, and that they use a standard population to account for differences in demographics.