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New strategies for HIV diagnostic algorithms

Multi-test strategies for the determination of HIV serostatus without the use of Western immunoblotting. New strategies for HIV diagnostic algorithms. Jane Feldman, Susan Wells, Michele Owen, and Tim Granade. Current HIV testing algorithm CDC/APHL -- 1993. Screen by EIA

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New strategies for HIV diagnostic algorithms

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  1. Multi-test strategies for the determination of HIV serostatus without the use of Western immunoblotting New strategies for HIV diagnostic algorithms Jane Feldman, Susan Wells, Michele Owen, and Tim Granade

  2. Current HIV testing algorithmCDC/APHL -- 1993 • Screen by EIA • Re-test reactive specimens in duplicate using same EIA • Specimens reactive in at least 2 of 3 tests are further tested by WB/IFA

  3. Changes in HIV diagnostic testing • Introduction of 3rd and 4th generation HIV EIAs • FDA approval of rapid HIV antibody screening tests • Use of HIV nucleic acid detection assays Can alternative strategies provide equivalent or better results?

  4. Methods • Samples (n=342) that were submitted to the CDC HIV CLIA Reference Laboratory • “Difficult” samples • Most submitted due to inability of public health labs to reach a definitive answer • Suspicion of HIV-2 • Many likely screened with Bio-Rad HIV1/2 plus O

  5. HIV diagnostic testing strategy • Standard algorithm (reference) • Biorad 1/2/O EIA / WB Biorad or Maxim • Additional testing • Abbott rDNA HIV-1/2 • Multi-spot HIV-1/2 • Algorithms analyzed • Dual EIA • EIA/RT • Triple tests • Specimens • N=342

  6. Proposed Testing Strategies for Laboratory HIV Testing Facilities A1 EIA (HIV-1) Strategy 1. HIV-1 EIA/WB/NAAT A1 (+) A1 (-) Negative for HIV-1 antibodies† Repeat A1 (in duplicate) A1 (- -) B2 Individual HIV-1 NAAT (option for initial plasma submissions) A1 (++ or - +) OR B1 HIV-1 WB or HIV-1 IFA Negative* Positive** Positive Negative Indeterminate Positive for HIV-1 antibodies and HIV-1 RNA Positive for HIV-1 antibodies Negative for HIV-1 antibodies† Inconclusive for HIV-1 antibodies; request redraw in 2-4 weeks; requires medical follow-up for further evaluation and testing †∞ * HIV-1 RNA not detected, however, a WB or IFA should be performed to confirm the absence of HIV-1 antibodies. Medical follow-up for further evaluation and testing may be required. ** It may be necessary to repeat a positive NAAT for confirmation † If window period infection is suspected, refer to Acute HIV Infection Testing, Strategy 4 ∞ If HIV-2 infection is suspected, refer to HIV-2 Testing, Strategy 5

  7. Biorad HIV-1/2 plus O N=342 P N Repeat in duplicate 177 165 N P 7 158 Western blot I N P 77 41 40 Reference serology 77 reactive, 41 indeterminate, 224 non-reactive

  8. A1 (++ or +-) A1 (-) Strategy 3. HIV-1/2 Dual Immunoassay A1 HIV-1/2 Immunoassay (e.g. EIA or CIA) Proposed Testing Strategies for Laboratory HIV Testing Facilities A1 (+) A1 (-) Negative for HIV-1 and HIV-2 antibodies† A1 (- -) Repeat A1 in duplicate A2 HIV-1/2 immunoassay* in duplicate A2 (- -) A1 (++ or + -) A2 (++ or + -) Inconclusive for HIV antibodies; request plasma redraw for NAAT† Requires medical follow-up for further evaluation and testing Presumptive positive for HIV-1 or HIV-2 antibodies; requires medical follow-up for further evaluation and testing HIV-2 Testing; Strategy 5, if applicable

  9. P N 243 99 Biorad HIV-1/2 plus O N P 11 88 Western blot I N P 76 19 4 Dual EIA / WB Abbott HIV-1/2 -Biorad HIV-1/2 plus O-WB N=342 76 reactive, 19 indeterminate, 247 non-reactive

  10. EIA/RT Biorad HIV-1/2 – Multispot HIV-1/2 N=342 P N 177 165 Multi-spot N HIV-2 U I HIV-1 78 6 1 1 79 85 reactive, 1 invalid, 184 non-reactive, 72 inconclusive

  11. EIA/RT Biorad HIV-1/2 – Multispot HIV-1/2 N=342 P N 184 165 Multi-spot N HIV-2 U I HIV-1 72 78 6 1 1 85 reactive, 1 invalid, 184 non-reactive, 72 inconclusive

  12. EIA/RT Abbott HIV-1/2 – Multispot HIV-1/2 N=342 P N 243 99 Multi-spot N HIV-2 U I HIV-1 73 5 1 1 19 79 reactive, 1 invalid, 243 non-reactive, 19 inconclusive

  13. P N 177 184 165 Abbott HIV-1/2 N P 7 77 88 Biorad repeat X2 70 Multi-spot 1 2 N I U 1 2 N I U 72 5 9 1 1 6 1 63 0 0 Three test algorithmStrategy 3/5 Biorad HIV-1/2 plus O N=342 84 reactive, 1 invalid, 1 undifferentiated, 184 non-reactive, 72 inconclusive

  14. Performance comparisons BR/AB/WB REF DATA Sensitivity = 98.7%; Specificity = 99.6%

  15. Algorithm summary dataStrategy 3 N=342 • *All Abbott and Multi-spot data are single runs. • a Inconclusive by Strategy 3

  16. Algorithm summary data N=342

  17. N N 2 2 1 1 7 0 34 2 1 36 87 reactive, 254 non-reactive, 1 invalid Reference serology Biorad HIV-1/2 plus O N=342 P N Repeat in duplicate 177 165 N P 7 158 Western blot I N P 77 41 40 Multi-spot

  18. GS HIV-1/2+O Multi-Spot OraQuick Uni-Gold Procleix Vir HIV-1 GS rLav Reveal Abbott WB Indeterminate WB positive 10 5 25 20 15 0 Days before Western blot positivity Sequence of Positivity NAT> 3rd Generation EIA>2nd Generation EIA= Rapid>1st Generation EIA

  19. Acknowledgements Jane Feldman Susan Wells Michele Owen Patrick Sprinkle

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