Limited utility of alanine aminotransferase screening of hepatitis C antibody-screened blood donors.

BACKGROUND

The introduction of hepatitis C virus (HCV) screening has significantly reduced the frequency of posttransfusion hepatitis C. To examine the current added value of alanine aminotransferase (ALT) screening, all donor screening at two large blood centers was reviewed.

STUDY DESIGN AND METHODS

From July 1991 through March 1994, 1,258,000 allogeneic blood donors were screened by enzyme immunoassay for anti-HCV: 343,000 donations by the first-generation test (HCV 1.0) and 915,000 donations by the second-generation test (HCV 2.0). Donations with positive EIA results were confirmed with a recombinant immunoblot assay.

RESULTS

Of these donors, 1,637 (0.13%) were confirmed as HCV-positive and 21,666 (1.72%) had elevated ALT. To estimate the additional margin of safety due to ALT screening, all donors who seroconverted were reviewed, and those donors who had elevated ALT but were HCV negative on a previous donation were identified. One hundred eleven HCV seroconversions were observed: 19 seroconversions from HCV 1.0-negative to HCV 1.0-confirmed-positive, 82 apparent seroconversions from HCV 1.0-negative to HCV 2.0-confirmed-positive, and 10 seroconversions from HCV 2.0-negative to HCV 2.0-confirmed-positive. The number of apparent HCV 1.0-negative to HCV 2.0-positive seroconversions was much greater than expected, which reflected the increased sensitivity of HCV 2.0. Only 15 donors were identified who had an elevated ALT on a previous HCV-negative blood donation, and all of these were among those who apparently seroconverted from HCV 1.0-negative to HCV 2.0-confirmed-positive. Out of the 10 HCV 2.0-seroconverting donors, no donor was found who was initially HCV 2.0 negative with elevated ALT and later was HCV 2.0 positive; nor were such donors found among 4 additional HCV 2.0-seroconverting donors.

CONCLUSION

With the introduction of HCV 2.0 screening. ALT appears to have little value as a surrogate test for hepatitis C, and ALT testing was unable to detect any donors who later seroconverted, as detected by HCV 2.0.