title: Loss of volunteer blood donors because of unconfirmed enzyme immunoassay screening results. Retrovirus Epidemiology Donor Study.
abstract: BACKGROUND
  Blood donors who test repeatably reactive on enzyme immunoassay (EIA) and are not confirmed as positive are a continuing problem for blood banks. Units are discarded and donors are deferred, in spite of multiple studies indicating that such donors are very rarely infected with the transmissible agents. Few data are available, however, with which to evaluate whether the discarded units are more likely to come from particular demographic subgroups.
  
  
  METHODS
  The Retrovirus Epidemiology Donor Study database of over 2 million allogeneic whole-blood donations collected in the years 1991 through 1993 was utilized. The prevalence of false-positive and indeterminate test results within demographic subgroups was computed for antibodies to human immunodeficiency virus, hepatitis C virus, and human T-lymphotropic virus (anti-HIV, anti-HCV, anti-HTLV, respectively) and hepatitis B surface antigen (false-positive only) as the proportion of donations that were repeatably reactive on EIA but negative or indeterminate on the confirmatory or supplemental test.
  
  
  RESULTS
  Several demographic groups with increased prevalence of false-positive and indeterminate anti-HIV results were the same females, younger age groups, blacks, and first-time donors. Likewise, many of the demographic subgroups with increased prevalence of false-positive and indeterminate anti-HCV results were similar: older age groups, non-whites, lower education levels, first-time donors, donors making directed donations, and donors who had received transfusions. For anti-HTLV, by contrast, the oldest group had the highest prevalence of false-positive results but the lowest prevalence of indeterminate results: blacks had the lowest prevalence of false positive results but the highest prevalence of indeterminate results.
  
  
  CONCLUSIONS
  If units that test repeatably reactive on EIA but that are not confirmed as positive are almost always from individuals not infected with the virus in question, then these results indicate that there may be sex-, race-, and/or age-linked proteins cross-reacting with the test kit materials. Elucidation of these antigenic determinates and their subsequent removal should be a priority.
authors.affiliation: American Red Cross Blood Services, Southeastern Michigan Region, Detroit, USA.
authors.forename: H E
authors.initials: HE
authors.lastname: Ownby
authors.forename: J J
authors.initials: JJ
authors.lastname: Korelitz
authors.forename: M P
authors.initials: MP
authors.lastname: Busch
authors.forename: A E
authors.initials: AE
authors.lastname: Williams
authors.forename: S H
authors.initials: SH
authors.lastname: Kleinman
authors.forename: R O
authors.initials: RO
authors.lastname: Gilcher
authors.forename: P
authors.initials: P
authors.lastname: Nourjah
mesh_terms: D001782:Blood Donors; D005189:False Positive Reactions; D015528:HIV Seroprevalence; D006508:Hepatitis Antibodies / Q000097:blood; D006801:Humans; D007124:Immunoenzyme Techniques / Q000592:standards; D012680:Sensitivity and Specificity
chemical_list: D006508:Hepatitis Antibodies