Study on the Seroincidence of Hepatitic C Virus Infection among blood donors in Korea

Oh, Heung Bum; Hwang, Yoo Sung; Kim, Doo Sung; Kim, Sang In; Lee, Soon Young; Han, Kyo Sup

Abstract

BACKGROUND
Since the introduction of anti-HCV assay, post-transfusion hepatitis (PTH) by Hepatitis C Virus (HCV) was remakably reduced. Recently, based on the estimation of HCV seroincidence rate in blood donors, an investigator insisted that alanine aminotransferase (ALT) test be discontinued as a surrogate marker. This study was designed to determine the HCV seroincidence in Korean blood donors.
METHODS
HCV seroincidence was calculated using repeat donors who had donated repeatedly during the 26 months from Nov. 1994 through Dec. 1996. To calculate the person-years according to ALT value, the computer database of the Korean National Red Cross (KNRC) was used in which results for anti-HCV by enzyme immunoassay (EIA) were filed up. To count the true incidence cases, who were defined as donors showing seroconversion by confirmatory test in two successive donation, seroconverted donors by EIA were individually reconfirmed whether they were true seroconverters. Finally, projected impact on HCV risk of discontining of ALT screening was calculated by using two important value previously known, such as periods of seroconversion window for anti-HCV and ALT preconversion window.
RESULTS
HCV seroincidence was estimated to be 13.79/100,000 person-years. Seroincidences according to the ALT groups were as follows; 13.22 in the normal ALT group (< or = 64 IU/L), 34.15 in the elevated group (65-130 IU/L), 87.13 in the highly elevated group (> or =131 IU/L). By this study, investigators also could find seroconverted donors, whose result for anti-HCV by immunoblot was positive at the first donation and changed to negative by EIA at the next donation, as many as 100 donors. Among these falsely seroconverted persons, 16% of donors showed elevated ALT value. 8 units per 1 million donations were estimated to be discarded only by abnormal results of ALT testing in Korea.
CONCLUSION
HCV seroincidence in Korean donors was 2.8 times as high as in American donors. HCV seroincidence calculated by this study seems to be somewhat lower than true rate because of the problem of summing-up the person-years. Considering that higher seroincidence results in more donors in seroconversion window phase, donor selection by careful history taking should be re-emphasized to reduce the seroincidence rate in Korean blood donation program.