Background: Since the mid-1980s, blood banks in the United States have screened donors for elevated alanine aminotransferase (ALT) in an effort to prevent posttransfusion hepatitis. The present study was designed to quantitate the residual value of ALT screening following the implementation of hepatitis C virus (HCV) assays.
Study design and methods: Two approaches were used. First, a database of 2.3 million donations made by 586,507 volunteer blood donors between 1991 and 1993 was used to compare the incidence of seroconversion to hepatitis B virus (HBV) and HCV marker positivity in donors with elevated ALT values and with normal ALT values. Second, the duration of ALT elevation prior to HBV and HCV seroconversion was determined from 34 well-documented cases of posttransfusion HBV and HCV; elevated-ALT window periods were multiplied by rates of HBV and HCV incidence in donors to project the yield of ALT screening. Predictive value and cost-effectiveness analyses were also performed to compare the value of ALT screening before and after HCV screening was implemented.
Results: Both approaches indicate that ALT testing does not detect HBV in the window phase but does currently identify approximately 3 HCV window-phase donations per 1 million donations; this contrasts with ALT detection of approximately 1800 HCV-infectious units per 1 million donations prior to anti-HCV screening. Currently, only 8 in 10,000 donated units with elevated ALT (negative anti-HCV) are infected with HCV. The cost of continued ALT screening was estimated at $7,931,000 per quality-adjusted year of life saved.
Conclusion: The yield, predictive value, and cost-effectiveness of ALT screening of blood donors have declined dramatically with the implementation of progressively improved anti-HCV assays. ALT screening of volunteer blood donors should be discontinued.