Study objective: To determine the prevalence and meaning of antibodies to the hepatitis C virus (HCV) in patients with nonalcoholic chronic liver diseases.

Design: Cross-sectional study.

Setting: The liver unit of a referral-based university hospital.

Patients: Three hundred and forty-six consecutive patients, including 137 with cryptogenic chronic liver disease, 156 with chronic hepatitis B, 47 with primary biliary cirrhosis, and 8 with persistently abnormal aminotransferase serum levels and normal liver histology. Among patients with cryptogenic liver disease, 41 received blood transfusions before discovery of liver disease and 18 had circulating nonorgan-specific autoantibodies. For comparison, 1495 apparently healthy volunteer blood donors were included in the study. LABORATORY INVESTIGATIONS: The presence of anti-HCV antibodies (anti-HCV) was determined by a recently developed enzyme-linked immunoassay.

Measurements and main results: In patients with cryptogenic liver disease, the prevalence of anti-HCV was 82% (95% CI, 76% to 89%), being higher (P = 0.02) in patients with histories of blood transfusion than in those with unknown sources of exposure. Antibodies to HCV were not detected in patients with antinuclear antibodies at high titer. Among patients with chronic hepatitis B, anti-HCV were found in 11% (CI, 5% to 18%) of those with hepatitis B virus (HBV)-associated DNA in serum and in 29% (CI, 17% to 43%) of those with undetectable HBV replication (P less than 0.05). The prevalence of anti-HCV in blood donors was 1.2% (CI, 1.1% to 1.3%).

Conclusions: Our results indicate that HCV infection probably plays an important etiologic role in cryptogenic liver disease and, in some patients, in chronic hepatitis B. Determining whether anti-HCV are present appears to be useful for differentiating viral from autoimmune chronic liver diseases.