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
D Jardine, S Best, EM Dax (National Serology Reference Laboratory, Australia) and Participating Blood & Blood Product Screening Laboratories
Blood Screening NAT EQASBlood 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
Blood Screening NAT EQAS 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
Chiron TMA Roche Ampliscreen
Sample ID A B A B
HIV load (geq/mL) 130 170 130 170
No. of results 16 16 2 2
No. reactive 16 15 2 2
Investigation; follow-up action
Blood Screening NAT QCBlood Screening NAT QC
Run No.
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46
S/C
o
0
5
10
15
20
25
30
Mean
Mean-2SD
Mean+2SD
cutoff
Luminometer 1
Luminometer 2
Panel 6, replicate 1Panel 6, replicate 2
Reagent Batch Change
Chiron TMA HIV external run control* results in laboratory with aberrant EQAS result
Invalidated run
*250 geq HIV RNA/mL; VQC
Blood Screening NAT EQASBlood Screening NAT EQAS
Subtype BSubtype BSubtype ASubtype A
Subtype CSubtype CSubtype DSubtype DSubtype ESubtype E
25002500 250250 2525 2.52.5
S/C
oS
/Co
00
55
1010
1515
2020
2525
cut-offcut-off
geq HIV RNA/mLgeq HIV RNA/mL
Chiron TMA results in dilution series of various HIV-1 subtypes
Panel 3, June ‘01
Blood Screening NAT EQAS Blood Screening NAT EQAS
All reactiveAll reactive
( 140 geq/mL) Results
1603.8 - 1400HIV loads (geq/mL)
1010No. HIV positive
samples
NRL
April ‘03
VQC
Dec ‘02
Origin
Distributed
Panel 8Panel 7
Panels 7 & 8: HIV components
DiscussionDiscussion
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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