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Longitudinal Quality Assurance of HIV Nucleic Acid Testing in Blood Screening

Longitudinal Quality Assurance of HIV Nucleic Acid Testing in Blood Screening. D Jardine, S Best , EM Dax (National Serology Reference Laboratory, Australia) and Participating Blood & Blood Product Screening Laboratories. Blood Screening NAT EQAS.

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Longitudinal Quality Assurance of HIV Nucleic Acid Testing in Blood Screening

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  1. Longitudinal Quality Assurance of HIV Nucleic Acid Testing in Blood Screening D Jardine, S Best, EM Dax (National Serology Reference Laboratory, Australia) and Participating Blood & Blood Product Screening Laboratories

  2. Blood Screening NAT EQAS • EQAS is designed to monitor an entire testing process • 3 NAT EQAS panels annually • 2 NRL; 1 VQC Laboratory (The Netherlands) • Each NRL panel designed to fulfil a specific objective • 10 laboratories (Australia, NZ, SE Asia) • Chiron TMA: 8 laboratories • Roche Ampliscreen: 2 laboratories • 2 replicate panels to each laboratory

  3. Blood Screening NAT EQAS Panel 6, September ‘02: Composition – HIV component • 7 HIV positive samples randomly distributed • HIV loads: 130 – 36000 geq/mL determined in Roche Amplicor HIV Monitor Results – Samples A& B Investigation; follow-up action

  4. Blood Screening NAT QC Chiron TMA HIV external run control* results in laboratory with aberrant EQAS result 30 Reagent Batch Change Mean+2SD 25 20 Mean 15 Mean-2SD S/Co 10 Panel 6, replicate 2 Panel 6, replicate 1 5 Invalidated run cutoff 0 12 18 22 26 28 34 38 42 44 10 14 16 20 24 30 32 36 40 46 0 2 4 6 8 Run No. *250 geq HIV RNA/mL; VQC Luminometer 1 Luminometer 2

  5. Blood Screening NAT EQAS Panel 3, June ‘01 Chiron TMA results in dilution series of various HIV-1 subtypes 25 20 Subtype A Subtype B 15 Subtype C S/Co Subtype D 10 Subtype E 5 cut-off 0 2500 250 25 2.5 geq HIV RNA/mL

  6. Blood Screening NAT EQAS Panels 7 & 8: HIV components Panel 7 Panel 8 Origin Distributed VQC Dec ‘02 NRL April ‘03 10 No. HIV positive samples 10 HIV loads (geq/mL) 3.8 - 1400 160 All reactive( 140 geq/mL) All reactive Results

  7. Discussion • EQAS Panel 6, sample B should be reactive 100% in TMA • 95% COV: 28 (95% CI 16-62) geq HIV RNA/mL (NRL evaluation) • Corroborated by data obtained in EQAS Panel 3 • 0.35% failure rate (S/CO ratio <1) of external run controls * • Ongoing rate since implementation of NAT screening (2000) • Results from low positive HIV samples in EQAS panels 7 & 8: concordant with reference results • Future panels will continue to monitor low levels of RNA *Australian Red Cross Blood Service data

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