Gershwin ME et al. (2005) Risk factors and comorbidities in primary biliary cirrhosis: a controlled interview-based study of 1032 patients. Hepatology 42: 1194–1202

Primary biliary cirrhosis (PBC) is a rare autoimmune disease that is costly to treat and increasing in prevalence. Although a genetic susceptibility has long been suspected, environmental factors are also likely to have a role in the etiology of PBC. Epidemiologic data relating to PBC risk factors are limited.

Gershwin et al. have considerably expanded the available data by conducting telephone interviews based on a modified version of the US National Health and Nutrition Examination Study (NHANES III) questionnaire. They interviewed 1,032 patients with PBC from 23 tertiary referral centers for liver disease, and 1,041 controls who were selected by random-digit dialing and matched for sex, 5-year age-group, ethnicity and geographic area.

The mean age at diagnosis of PBC was 51 ± 10 years. Comorbid autoimmune conditions were common: the prevalence of Raynaud and Sjögren syndromes was 6–20 times higher in patients than controls (P <0.0001 for both) and rates of systemic lupus erythematosus, scleroderma and autoimmune thyroid disease were also elevated. The presence of a first-degree relative with PBC (adjusted odds ratio [AOR] = 10.736) and a history of urinary tract infection (AOR = 1.511), smoking (AOR = 1.569) or use of hormone replacement therapy (AOR = 1.548) were all associated with an increased PBC risk.

Although information was obtained directly from patients without medical confirmation, this study provides valuable information about PBC risk factors. The authors suggest this should be consolidated by initiating linkage studies, to clarify genetic contributors, and animal studies to characterize the environmental determinants of risk.