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Comparison of the HIV LIA vs WB on HIV-Negative Samples

Comparison of the HIV LIA vs WB on HIV-Negative Samples. CDC-HIV Diagnostics Meeting “New Diagnostic Technologies” Dec 5-7, 2007 Dr. John Kim National Laboratory for HIV Reference Services Public Health Agency of Canada Ottawa, Ontario. sample. EIA. non-reactive. REPORT. screening.

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Comparison of the HIV LIA vs WB on HIV-Negative Samples

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  1. Comparison of the HIV LIA vs WB on HIV-Negative Samples CDC-HIV Diagnostics Meeting “New Diagnostic Technologies” Dec 5-7, 2007 Dr. John Kim National Laboratory for HIV Reference Services Public Health Agency of Canada Ottawa, Ontario

  2. sample EIA non-reactive REPORT screening Repeat reactive confirmatory (a) Western blot (HIV-1) (b) RIPA (HIV-1, HIV-2) (C) LIA (HIV-1/HIV-2) Final Diagnosis (d) PCR –Roche, Hpol, gp41, HIV-2 RNA – bDNA, Roche, Abbott, HIV-2 Q Figure 1. HIV Testing (general)

  3. Positive Predictive Values (Importance of Supplementary Tests) Prevalence EIAEIA + WB 0.02 % 9% 89.3 %* 0.04 % 16.7 % 95.2 % 0.40 % 66.7 % 99.5 % 1.0 % 83.5 % 99.8 %

  4. INNO-LIA HIV (new technology ?) • New anti-human immunodeficiency virus immunoblot assays resolve non-specific Western blot results. (Zaaijer et al, Transfusion, 37:193, 1997). • Validation of a new immunoblot assay for confirmation of human immunodeficiency virus infection (Zaaijer et al, Transfusion, 38:776, 1998). • Ability of the Innogenetics Inno-Lia to distinguish HIV-1, HIV-2 and dually reactive sera. (Granade et al, Abstr. Gen Meet Am Soc Microbiol, 92:416 [T-47[, 1992. • Confirmation of HIV infection with the line immune assay (INNO-LIA) using whole blood impregnated filter paper discs. (Kestens et al, Abstr. Int Conf Aids 5:309 [TBP 135], 1989.

  5. p31 p17 Detection of non-Subtype B HIV reference samples on Subtype B HIV-1 (WB & LIA) antigen kits “O” ? A D C E F F + “O” ? A D C E F F 2 2 gp160 gp120 gp41 HIV-1 HIV-2 p24

  6. gp41 p31 p24 p17 HIV-2 Reference Samples and atypical HIV-1 WB Patterns 1 2 3 4 5 6 7 gp160 1 2 3 4 5 6 7 gp120 HIV-1 HIV-2

  7. HIV WB Quality ISSUES-Canada

  8. Methods • BIO-RAD Wb vs INNOGenetics HIV 1/2 Score • > 1000 samples, (2002-2007) • n=823 (77-pos; 746-neg), final status known/WB-LIA results • Neg samples (746) • n=472, LIA-neg/Wb-neg • n=232*, LIA-neg/Wb-ind • n=42, LIA-ind/Wb-ind [23],LIA-ind/Wb-neg [15], • LIA-pos/Wb-pos/neg/ind [4]

  9. NLHRS n=823 positive negative 73 258 positive TP FP Wb 4 488 negative FN TN HIV Wb vs NLHRS sens – 73/(73 +4)= 95% spec – 488/(488+258)= 65% PPV – 73/(73 +258)= 22% NPV – 488/(488+4)= 99%

  10. NLHRS n=823 positive negative 77 42 positive TP FP LIA 0 704 negative FN TN HIV LIA vs NLHRS sens – 77/(77 +0)= 100% spec – 704/(704+42)= 94% PPV – 77/(77 +42)= 65% NPV – 704/(704+0)= 100%

  11. Comparison of WB vs LIA Patterns on HIV-Negative Samples (NLHRS)

  12. HIV-1 WB (BIO-RAD) gp 160 gp 120 p66 p55 p51 gp 41 p31 p24 p17 HIV-1 gp 120 gp 41 p31 p24 p17 gp 105 gp 36 INNO-LIA – HIV 1&2 HIV-1 HIV-2

  13. HIV-1 WB (BIO-RAD) gp 160 gp 120 p66 p55 p51 gp 41 p31 p24 p17 HIV-1 gp 120 gp 41 p31 p24 p17 gp 105 gp 36 INNO-LIA – HIV 1&2 HIV-1 HIV-2

  14. HIV-1 WB (BIO-RAD) gp 160 gp 120 p66 p55 p51 gp 41 p31 p24 p17 HIV-1 gp 120 gp 41 p31 p24 p17 gp 105 gp 36 INNO-LIA – HIV 1&2 HIV-1 HIV-2

  15. Living with the Wb-Improvements • Wb still most widely used (licensed) confirm tool • Known for years (89.3% [266/298]; BIORad; p20) • Review/Change interpretative criteria…Harmonize international criterias • Combine wb interpretative criteria • eg: CDC/ASTPHLD + WHO [Tebourski et al, 2004] • License new tests (eg. LIA) – patent issues ? • LIA – test of choice in NLHRS • sens (100% vs 95%), spec (94% vs 65%) • PPV (65% vs 22%), NPV (100% vs 99%)

  16. % False Positives OMIT SLIDE ? % Prevalence

  17. Predictive Values OMIT SLIDE ??? Positive predictive value (PPV) PPV = TP/TP +FP (x 100) Negative predictive value (NPV) NPV = TN/TN+FN (x100) How accurately a test predicts the presence or absence of analyte (disease) ! (i) sensitivity - incidence of true positives in those with disease (ii) specificity - incidence of true of negatives in those without disease (iii) prevalence - number of actual cases (of disease) in the population. Galen RS and Gambino SR. Beyond Normality: The Predictive Value and Efficiency of Medical Diagnosis. New York: Wiley, 1975.

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