[Natural history of HCV seropositive cases found in health screening]

In order to elucidate causative factors in HCV infection and natural history of HCV seropositive cases, examinees of adult health screening in two rural districts near Asahikawa (Groups A and B) were tested for HCV antibody and the clinical data of the HCV seropositive cases were retrospectively followed up. The examinees who showed cut-off index not less than 2.0 in C100-3 antibody test were taken as HCV seropositive cases. HCV seropositive rate was 5.1% for Group A, compared with 2.7% for Group B. HCV related factors were examined between HCV seropositive cases and age/sex-matched controls in the same group. As a result, blood transfusion and operation histories proved to be responsible for HCV seroreactivity in both Groups A and B. Although no significant difference was noted in blood transfusion and operation histories between Groups A and B, the rates with past history of liver disease, HBV exposure, and advanced age above 60 were significantly higher for Group A, suggesting HCV related factors other than blood transfusion and operation to be regionally different. Majority of HCV seropositive cases (79.2%) were ALT-normal, but 42.5% and 32.5% of this group showed ZTT- and ADA-abnormality, compared with 6.5 and 10.9% of the normal ALT group of HBV carriers respectively. HCV seropositive cases could be classified as ALT-abnormal (group I), ALT-transition from normal to abnormal (group II) and ALT-persistently normal (group III), depending on the change in ALT level during follow-up period. Of these, group III represented 38% of HCV seropositive cases. The rate in which the HCV seropositive cases of this group III showed ZTT abnormality at least once during follow-up period was 81% and significantly higher than 43.5% for HBV carriers with persistently normal ALT level. Significant correlations between ZTT and IgG values were noted for both HCV seropositive cases and HBV carriers with persistently normal ALT level. For HCV seropositive cases, ZTT and IgG showed broad distributions from low to high values, compared with distribution in normal area for HBV carriers. ZTT-abnormality in HCV seropositive cases may reflect some hepatic changes, because no other factors contribute to their ZTT abnormality. At least, some of group III HCV seropositive cases found in health screening may represent those who make no progress with chronic persistent hepatitis.