Lichen planus and liver diseases: a multicentre case-control study. Gruppo Italiano Studi Epidemiologici in Dermatologia (GISED).

OBJECTIVE To assess the association of lichen planus with liver complaints and with known aetiological factors of liver diseases. DESIGN Multicentre case-control study. Interviews were conducted by trained medical investigators on the basis of a structured questionnaire. At the interview patients and controls were asked for consent to blood samples being taken to determine transaminase activities and the presence of hepatitis B virus surface antigen. SETTING Outpatient departments of 27 Italian general and teaching hospitals that were collaborating in the Gruppo Italiano Studi Epidemiologici in Dermatologia (GISED). SUBJECTS Incident cases and controls were eligible. A total of 577 patients with lichen planus and 1031 controls with dermatological diseases other than lichen planus were interviewed. Less than 1% of the people contacted refused to participate. Patients and controls were matched for sex and age in five year intervals. RESULTS The risk of lichen planus was higher in patients with a history of liver diseases requiring hospital admission or specialist consultation (relative risk = 1.6; 95% confidence interval = 1.2 to 2.2), those who had had liver biopsy (5.5; 1.9 to 15.6), and those with a history of viral hepatitis (1.9; 1.1 to 3.1). High activities of liver enzymes and positive results of tests for hepatitis B virus surface antigen were also associated with lichen planus. The association with alcohol consumption was not clearly confirmed by a dose-risk relation. CONCLUSION This study adds quantitative epidemiological evidence to the clinical observation that liver disease is a risk factor for lichen planus although not a specific marker of it.