1 / 9

Objectives

Comparative Performance of Dual 3rd Generation Immunoassays as a Potential Laboratory-Based HIV-1/2 Testing Strategy. B. Bennett, S. Fordan, O. David, M. Salfinger, M. Chan, D. Willis, S. Crowe, Florida Department of Health, Bureau of Laboratories-Jacksonville, FL., USA. Objectives. Primary:

rania
Download Presentation

Objectives

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Comparative Performance of Dual 3rd Generation Immunoassays as a Potential Laboratory-Based HIV-1/2 Testing Strategy.B. Bennett, S. Fordan, O. David, M. Salfinger, M. Chan, D. Willis, S. Crowe, Florida Department of Health, Bureau of Laboratories-Jacksonville, FL., USA.

  2. Objectives Primary: • To assess clinical performance of each immunoassay for possible ITN purposes within our current algorithm, not specifically for a dual immunoassay algorithm design. Strategy-specific: • Increase algorithm sensitivity w/o compromising specificity as compared to a traditional algorithm. • Demonstrate potential reagent cost-effectiveness on seropositive results as compared to a traditional algorithm. • Demonstrate improve testing TAT on non-seronegative reporting. • Reduce the number of inconclusive reports.

  3. Methods • Assay selection;BioRad’s HIV-1/2 Plus O EIA Siemens Advia Enhanced HIV-1/O/2 • n = 2,765 fresh serum samples tested by both 3rd generation immunoassays. • TP = 92 (3.3%), 90 WBlot +, 1 NAAT +, 1 subsequent seroconversion • TN = 2,673

  4. Strategy 3. HIV 1/2 Dual Immunoassay A1 = HIV1/2 immunoassay(e.g. EIA or CIA) n = 2765 TP = 92 (3.3%) A1 (+) BR1/2/O = 98E1/2/O = 98 A1 (-) Negative for HIV-1 & HIV-2 antibodies BR1/2/O = 2667E1/2/O = 2667 A1 (- -) Repeat A1**This study did not include the (duplicate) ? ? repeat AI pathway. A2 = HIV 1/2 immunoassay in duplicate (e.g. EIA or CIA or non-waived rapid) A2(- -) E1/2/O = 2BR1/2/O = 2 A1 (++ or +-) A2 (++) (+-) Presumptive positive for HIV-1 or HIV-2 antibodies; requires medical follow-up for further evaluation and testingE1/2/O = 96 BR1/2/0 = 96A1/A2 sensitivity = 100% PPV = 95.8% A1/A2 specificity = 99.85% NPV = 100% Inconclusive for HIV antibodies; request plasma redrawfor NAAT *. Requires medical follow-up for further evaluation and testing. HIV-2 testing; Strategy 5, if 1 or more of the following apply: 1) Indicated by clinical presentation 2) Indicated by local HIV-2 prevalence 3) Indicated by client/patient travel or risk history *If window period infection is suspected, refer to Acute HIV Infection Testing, Strategy 4.

  5. Table 1Individual Assay & Strategy PerformanceAssay(s) Clinical Sensitivity Clinical Specificity * Optional replacement with Advia HIV-1/O/2 w/ same performance.** Based on Western Blot negative and/or limited seronegative follow up.

  6. Table 2 Discordant Results Specimen HIV-1/2 Plus O Advia HIV-1/O/2 Western NAAT Follow up S/CO* Index* Blot (HIV-1) (Aptima HIV-1 RNA) * <1.0 s/co or index values are exact, >1.0 s/co or index values are averages of replicates. Color representations; false positive screens, false negative blots,confirmed HIV-1 acute infections.

  7. Conclusions • Increased sensitivity over the reference method. • Increased specificity over either 3rd generation immunoassay in stand-alone use. • Comparable specificity to a licensed HIV-1 WBlot, the licensed HIV-1 NAAT assay and several POC HIV-1/2 rapid devices. • Did not demonstrate the ability to detect a very limited number of confirmed HIV-1 acute infections. • Laboratory-TAT of seropositive results potentially could be reduced by 1-3 days. • Diagnostic reagent costs could be reduced for non-negative specimens by 26-43%.

  8. Table 3Application ComparisonsStrategy Turn-Around-Time (non-negatives) Reagent Costs

  9. Study Notes & Needs • Need to expand study size & include more acute and early infections(focus on increasing specificity w/o compromising the improved sensitivity); - Better assay(s) selections? - The addition of a 3rd assay? - The use of a S/CO threshold value to assist in further testing, referrals and/or reporting needs? • Need for reproducibility data over more than one lot# per assay. • Need for seroconversion panels(budgetary restraints in our case) • Note: Based on this study’s limited number of AIs (4) and if AIT is desired, perhaps consider the Strategy 5 add-on. • Note: Large automated analysis platforms are often required to accompany these newer diagnostic assays and possibly could impact the cost-effectiveness of a dual immunoassay algorithm. Use of other diagnostic applications (HBV, HCV, etc.) on the secondary platform may counter some of the additional costs. • Note: The “Random access” feature of at least one immunoassay has the potential to decrease TAT in a dual immunoassay algorithm but the “control bracketing” requirement may lessen the appeal when testing small numbers of initial reactives.

More Related