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 – geq/mL determined in Roche Amplicor HIV Monitor
Results – Samples A& B
Chiron TMA
Roche Ampliscreen
Sample ID A B
HIV load (geq/mL)
130
170
No. of results 16 2
No. reactive 15
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 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46
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
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
No. HIV positive samples 10 10
HIV loads (geq/mL)
160
Results
All reactive ( 140 geq/mL)
All reactive

7. *Australian Red Cross Blood Service data
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