title: Clinical significance of nondiscriminated reactive results with the Chiron Procleix HIV-1 and HCV assay.
abstract: BACKGROUND
  A NAT was developed (Procleix multiplex, Chiron Corporation) to simultaneously detect HIV-1 and HCV RNA with multiplex transcription-mediated amplification (mTMA) on pooled or single donations. HIV-1 and/or HCV RNA discriminatory probes confirm infection and discriminate the virus type. When a multiplex reactive sample does not react in discriminatory assays, the result is considered nondiscriminated reactive (NDR) and the donor status is uncertain. This study was designed to determine the clinical significance of NDR results.
  
  
  METHODS
  Three years of donor NAT and serology results were reviewed to determine HCV and HIV-1 infection rates as well as NDR events. Index NDR and seronegative donations were retested by mTMA and serology. Follow-up samples were tested by serology, mTMA, and PCR (selected samples).
  
  
  RESULTS
  From April 1999 through April 2002, 5.1 million donations were screened with Procleix HIV-1 and HCV mTMA. The observed NDR rate declined from 0.014 percent (1 in 7242) to 0.0053 percent (1 in 18,795). None of the 462 donors with index NDR donations and additional NAT and serology data (from 724 donation and follow-up samples) were found infected.
  
  
  CONCLUSIONS
  In most NDRs, the original mTMA reactivity is not reproducible and likely related to technical errors (mTMA cross-contamination). The retest and clinical follow-up data, combined with published evidence that the two discriminatory assays have the same sensitivity as multiplex HIV-1 and HCV, support the recommendation that donors with an NDR result for whom the multiplex reactivity cannot be reproduced should either not be notified or be deferred or should be counseled that they are not infected and expeditiously reinstated.
authors.affiliation: Blood Systems Laboratory and Arizona State University, Tempe, 85282, USA. jmcauley@bloodsystems.org
authors.forename: Joan D
authors.initials: JD
authors.lastname: McAuley
authors.forename: Sally
authors.initials: S
authors.lastname: Caglioti
authors.forename: Robert C
authors.initials: RC
authors.lastname: Williams
authors.forename: Gene F
authors.initials: GF
authors.lastname: Robertson
authors.forename: Larry
authors.initials: L
authors.lastname: Morgan
authors.forename: Leslie H
authors.initials: LH
authors.lastname: Tobler
authors.forename: Michael P
authors.initials: MP
authors.lastname: Busch
mesh_terms: D001782:Blood Donors; D015497:HIV-1 / Q000302:isolation & purification*; D016174:Hepacivirus / Q000302:isolation & purification*; D006801:Humans; D008403:Mass Screening / Q000379:methods; D021141:Nucleic Acid Amplification Techniques; D015203:Reproducibility of Results; D014766:Viremia / Q000175:diagnosis*