[Risk factors of hepatitis C virus infection].

In order to clarify the risk factors of hepatitis C virus (HCV) infection, past medical histories, family histories of liver disease, and lifestyle factors (smoking and drinking habits) were compared between anti-HCV positive cases and anti-HCV negative controls. Studies were 433 anti-HCV positive cases and 298 negative controls, all of whom were out-patients with chronic hepatitis or liver cirrhosis. The findings were contrasted with the risk factors of hepatitis B virus (HBV) chronic infection. Multiple logistic regression analysis revealed the following findings. Prevalence of anti-HCV among patients with chronic hepatitis or liver cirrhosis increased with age, while prevalence of HBsAg decreased with age. Histories of blood transfusion were closely associated with the risk of HCV infection. Adjusted relative risk for patients with a history of blood transfusion was estimated to be 2.97 (95% confidence intervals: 1.88-4.71) in comparison with the risk for patients without it. Any family history of liver disease was not related with the risk of HCV infection, while mother's history of liver disease was significantly associated with the risk of chronic HBV infection (adjusted relative risk was 2.96 with 95% confidence intervals: 1.32-6.62).