Probability of false initial and repeat ID-NAT reactive donations. Marion Vermeulen IPFA Rome 2014

Transcription

1 Probability of false initial and repeat ID-NAT reactive donations Marion Vermeulen IPFA Rome 2014

2 Overview of SANBS SANBS is a non profit organization Provides a vein to vein blood transfusion service in 8 of the 9 provinces in SA. WPBTS in Western Cape 805,000 units of blood collected annually (100% voluntary) units bled daily 2 testing centres - Johannesburg and Durban Also test for Namibia BTS (ID-NAT as well) 7 blood processing centres 84 blood banks serving > 600 hospitals and clinics. SANBS is accredited with the South African National Accreditation System (SANAS) Specific laboratories are ISO accredited HQ in Johannesburg

3 Background The package insert of the Ultrio assay (Hologics/Grifols) suggests the use of discriminatory (d) HBV, HCV and HIV assays for testing of ID-NAT initial reactive (IR) donations. SANBS follows this dhxv test algorithm for both seronegative and seropositive donations, but also tests the Ultrio IR samples in duplicate repeat assays.

4 NAT & Serology Testing Algorithm PRISM Screening Initial reactive Ultrio Screening Initial reactive PRISM repeat 1 PRISM repeat 2 Ultrio repeat 1 Ultrio repeat 2 Concordant NAT & serology yield Ultrio RR/dHXV Reactive and PRISM RR (Defer donor) Potential NAT Yield Ultrio RR and/or dhxv Reactive, PRISM negative Defer and Recall donor Potential Serology Yield Discriminatory tests dhxv dhbv dhcv PRISM RR, Immunoblot/HBsAg neutralization Pos, NAT neg or NRR Defer and recall donor NAT nonrepeat reactive (NRR) Donation discarded but donor eligible to donate again Anti-HBc on next donation Confirmation of Potential Yields using sample FFP unit Q-PCR and multiple repeat Ultrio (5x) and dhxv (5x) p24 Ag, immunoblot, HBsAg neutr., anti-hbc (IgM & IgG), anti-hbs titre dhiv

5 Aim To review the sensitivity and specificity of the Ultrio and dhxv reactivity's after five year of ID-NAT screening. To evaluate the HIV-1, HBV and HCV infection status in subsequent donations of seronegative donors with a NRR NAT result to determine whether the IR NAT result could possibly reflect a true infection

6 Annual proportion of initial NAT reactives that are repeat and nonrepeat reactive Month/Year Total Donations (Initial Reactives) %RR of IR %Concordant of IR % potential yields of IR %NRR of IR Specificity % NAT Year (4012) 1289 (32.13%) 1064 (26.5%) 225(5.60) 2723 (67.87%) NAT Year (5261) 1826 (34.71%) 1572 (29.9%) 253(4.81) 3435 (65.29%) NAT Year (3999) 2133 (53.34%) 1936 (48.4%) 197(4.92) 1866 (46.66%) NAT Year (3564) 2758 (77.38%) 2559 (71.8%) 199(5.58) 806 (22.62%) 99.9 NAT Year (3757) 2802 (74.58%) 2564 (68.2%) 238(6.33) 955 (25.42%) Total (20593) 10808(52.48%) 9695 (47.1%) 1112(5.40%) 9785(47.5%) 99.75

7 Five year ID-NAT screening data of South African National Blood Service (SANBS) 3,799,509 donations screened 10,808 (0.28%) Ultrio RR and/or dhxv R (0.27%) Ultrio NRR/NDR (89.7%) seropositive 1112 (10.3%) seronegative 19/8529 (0.22%) potential HBV 8510/8529 (99.78%) false IR

8 Proportion of confirmed NAT yields# 5 year Ultrio screening data SANBS # confirmed by: follow up Viral load on plasma unit Replicate Ultrio (5x) and dhbv (5x) on plasma unit NAT yield category n (%) Ultrio Initial reactive Ultrio repeat 1 Ultrio repeat 2 Potential NAT yield* 1112 (100%) confirmed positive 644 (57.9%) dhbv dhcv dhiv unresolved 60 (5.3%) false positive 408 (36.7%) *seronegative Ultrio RR and/or dhxv R.

9 Impact of ID-NAT algorithm on recognition of confirmed NAT yields# # confirmed by: follow up Viral load on plasma unit Replicate Ultrio (5x) and dhbv (5x) on plasma unit Ultrio Initial reactive Ultrio repeat 1 Ultrio repeat 2 dhbv Ultrio dhxv n (%) RR R 504 (78%) RR NR 104 (16%)* NR R 36 (5.6%)* All confirmed 644 (100%) dhcv dhiv * All HBV confirmed

10 Ultrio/dHXV reactivity in confirmed ID-NAT yields Confirmed NAT yields dhiv reactive dhcv reactive dhbv reactive dhxv nonreactive Potential Yields 235 (21.1%) (100%) 105 (9.4%) (100%) 513 (46.1%) (100%) 259 (23.3%) (100%) Ultrio RR Ultrio R,NR Ultrio NRR 162 (14.6%) (68.9%) 3 (0.26%) (2.9%) 275 (24.7%) (53.6%) 34 (3.0%) (13.1%) 3 (0.3%) (1.3%) (5.5%) (11.9%) 70 (6.3%) (27.0%) 36 (3.2%) (7.0%) Total confirmed 165 (14.8%) (70.2%) 3 (0.26%) (2.9%) 372 (33.4%) (72.5%) 104 (9.3%) (40.2%) All 1112(100%) 474 (42.6%) 134 (12.0%) 36 (3.2%) 644 (57.9%)

11 Confirmed positive Yields dhiv reactive dhcv reactive dhbv reactive dhxv nonreactive 1200 Confirmed positives Potential Yields Ultrio RR Ultrio R,NR Ultrio NRR Total confirmed

12 Ultrio/dHXV reactivity in false reactive or unresolved ID-NAT yields dhiv reactive dhcv reactive dhbv reactive dhxv nonreactive Potential Yields 235 (21.1%) (100%) 105 (9.4%) (100%) 513 (46.1%) (100%) 259 (23.3%) (100%) False and unresolved NAT yields Ultrio RR Ultrio R,NR Ultrio NRR Total false 37 (3.3%) (15.7%) 42 (3.8%) (40.0%) 54 (4.8%) (10.5%) 45 (4.0%) (17.4%) 2 (0.18%) (0.9%) 2 (0.18%) (1.9%) 48 (4.3%) (9.4%) 100 (9.0%) (38.6%) 20 (1.8%) (8.5%) 51 (4.6%) (48.6%) 7 (0.63%) (1.4%) 59 (5.3%) (25.1%) 95 (8.5%) (90.5%) 109 (9.8%) (21.2%) 145 (13.0%) (56.0%) All 1112(100%) 178 (16.0%) 152 (13.7%) 78 (7.0%) 408 (36.7%)

13 Confirmed False positive yields dhiv reactive dhcv reactive dhbv reactive dhxv nonreactive False positives Potential Yields Ultrio RR Ultrio R,NR Ultrio NRR Total false

14 Five year ID-NAT screening data of South African National Blood Service (SANBS) 3,799,509 donations screened 10,808 (0.28%) Ultrio RR and/or dhxv R (0.27%) Ultrio NRR/NDR (89.7%) seropositive 1112 (10.3%) seronegative 19/8529 (0.22%) potential HBV 8510/8529 (99.78%) false IR

15 NRR donor follow study Donors or infection category Ultrio NRR/dHXV NR group Ultrio NR control group p value Initial reactive donors Donors returning 8529 (82.7%) (82.7%) Return donations (8.2) (6.6) OBI infections in one of next bleeds 14 (0.164%) 5 (0.015%) < HBV seroconversions in next bleed 5 (0.059%) 4 (0.012)% Average HBV seroconversion interdonation interval (range) 81 (64-118) 255 (77-381) HIV seroconversions in next bleed 3 (0.035%) 8 (0.024%) 0.57

16 Percent confirmed in subsequent donation Ultrio NRR/dHXV NR group Ultrio NR control group 0,18% 0,16% 0,14% 0,12% 0,10% 0,08% 0,06% 0,04% 0,02% 0,00% 0,16% 0,02% 0,06% 0,04% 0,01% 0,02% OBI infections in one of next bleeds HBV seroconversions in next bleed HIV seroconversions in next bleed

17 Summary Overall 644 (57.9%) potential NAT yields were true infections 408 (36.7%) were false reactive 60 (5.4%) were unresolved. The duplicate repeat Ultrio algorithm detected 608 (94.4%) and the dhxv assays 540 (83.8%) of 644 confirmed infections. The Ultrio repeat algorithm falsely reacted 330 (80.9%) and the dhxv assay 263 (64.5%) times in 408 false reactive samples. 8510/8529 (99.78% ) of Ultrio NRR/NDR donations were false IR

18 Conclusion The combined Ultrio repeat/dhxv algorithm detected 408/1051(39%) false reactive and may have missed 19 NRR/NDR samples (0.16%) from possible low viral load HBV infections. If we considered a serology like repeat test strategy and the release of (anti-hbc NR) Ultrio NRR donations we could have released components from 8515 safe donations but potentially missed 5 low level HBV WP donations*. A triplicate Ultrio repeat test strategy for seronegative donations would have eliminated dhxv assays on IR donations (50%). A straight dhxv algorithm seems more suitable for seropositive donations and for identifying double infections. *Residual risk of WP donations 1:27,000 or 140 infections in the 5 year study period

19 Acknowledgements Nico Lelie Lelie Research Josephine Mitchel SANBS Charl Coleman SANBS Nomaphelo Sofute SANBS Ronel Swanevelder SANBS Linzi Ford SANBS Cordelia Mmemu - SANBS

20 THANK YOU

21 False positive plasma bags Index donation ULT 1st HBsAg 1HBsAg 2 HBsAg 3neut % Plasma dhbv 1 Plasma dhbv 2 Plasma dhbv 3 Plasma dhbv 4 Plasma dhbv 5 Plasma HBsAg Plasma A-HBc IgM Plasma A-HBc Total Plasma A-HBs Retest results ID to Retest interval ULT 1 dhbv HBsAg A-HBc A-HBc IgM Total Anti-HBs titre