Long-term trend of decreasing frequency of hepatitis B virus infection.

Statistical and histopathological analysis was carried out to determine whether hepatitis B surface antigen (HBsAg) with the autopsy diagnosis of hepatitis, cirrhosis, and hepatocellular carcinoma declined during 1964-1991. In this study, the liver specimens from 673 autopsy cases at Nagasaki University Hospital were used, and these materials were stained for HBsAg with immunoperoxidase method. For statistical calculation, we used Cochran's chi-square test with one degree of freedom for linear trend for proportions. We investigated HBsAg positive rates for the four time periods, 1964-1970, 1971-1977, 1978-1984, and 1985-1991, and for the diagnosis of hepatitis, cirrhosis, and hepatocellular carcinoma. The decreasing linear trend of HBsAg positivity with time was significant for hepatocellular carcinoma and cirrhosis.