ABSTRACT
There are apparently large geographical and secular variations in the prevalence of
primary biliary cirrhosis worldwide. Most studies suggest that the disease is most
common in Northern Europe, particularly northern Britain and Scandinavia, and that
the prevalence is increasing. This comprehensive review of the literature explores
to what extent these variations could be real rather than artifactual due to lack
of comparability among studies. The major design flaws are examined and guidelines
for better practice are outlined. It is hoped that other researchers will utilize
these recommendations for future studies so that true variations can be identified
and hypotheses regarding disease causation may be formulated and investigated. These
guidelines include: stringent case inclusion criteria; definition of date of disease
onset; well-defined study period, area and population; multiple case finding methods;
rigorous tracing of all possible cases. Preliminary results of the authors' study
using these guidelines are described and report a point prevalence of 235 per million
population in 1994 in the north of England, the highest yet reported.
KEY WORDS
primary biliary cirrhosis - liver disease - epidemiology - guidelines - review of
literature - geographical variation
