Hiv testing procidures by Dr Munawar Khan SACP
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This document provides information about rapid HIV testing, including 4 FDA-approved rapid HIV tests, how the tests work, their sensitivity and specificity, and examples of their use in various outreach and clinical settings. It discusses that while rapid HIV tests can significantly increase the number of people receiving their results, some may receive false positive results initially before confirmatory testing. It emphasizes the importance of confirmatory testing after an initial positive rapid HIV test result.
Hiv testing procidures by Dr Munawar Khan SACP
- 1. Rapid HIV Testing: Presented by: Dr. M. Munawar Khan BCC COORDINATOR SACP
- 2. Rapid HIV Testing: 2005 Update Presentation of Bernard M. Branson, M.D. Associate Director for Laboratory Diagnostics Division of HIV/AIDS Prevention Presented by: Dr. M. Munawar Khan BCC COORDINATOR SACP
- 3. Awareness of Serostatus among Persons with HIV, United States Number HIV infected 850,000 - 950,000 Number unaware of their HIV infection 180,000 - 280,000
- 4. Advancing HIV Prevention: New Strategies for a Changing Epidemic Four priorities: 1. Make voluntary HIV testing a routine part of medical care 2. Implement new models for diagnosing HIV infections outside medical settings 3. Prevent new infections by working with persons diagnosed with HIV and their partners 4. Further decrease perinatal HIV transmission MMWR April 18, 2003
- 5. Four FDA-approved Rapid HIV Tests Sensitivity Specificity (95% C.I.) (95% C.I.) OraQuick Advance - whole blood 99.6 (98.5 - 99.9) 100 (99.7-100) - oral fluid 99.3 (98.4 - 99.7) 99.8 (99.6 – 99.9) - plasma 99.6 (98.5 - 99.9) 99.9 (99.6 – 99.9) Uni-Gold Recombigen - whole blood 100 (99.5 – 100) 99.7 (99.0 – 100) - serum/plasma 100 (99.5 – 100) 99.8 (99.3 – 100)
- 6. Four FDA-approved Rapid HIV Tests Sensitivity Specificity (95% C.I.) (95% C.I.) Reveal G2 - serum 99.8 (99.2 – 100) 99.1 (98.8 – 99.4) - plasma 99.8 (99.0 – 100) 98.6 (98.4 – 98.8) Multispot - serum/plasma 100 (99.9 – 100) 99.9 (99.8 – 100) - HIV-2 100 (99.7 – 100)
- 7. OraQuick Advance HIV-1/2 CLIA-waived for finger stick, whole blood, oral fluid; moderate complexity with plasma Store at room temperature Screens for HIV-1 and 2 Results in 20 minutes
- 8. Obtain finger stick specimen…
- 9. Insert loop into vial and stir
- 10. Collect oral fluid specimens by swabbing gums with test device. Gloves optional; waste not biohazardous
- 11. Insert device; test develops in 20 minutes
- 12. Reactive Control Positive HIV-1/2 Positive Negative Read results in 20 – 40 minutes
- 13. Uni-Gold Recombigen CLIA-waived for finger stick, whole blood; moderate complexity with serum, plasma Store at room temperature Screens for HIV-1 Results in 10 minutes
- 14. Add 1 drop specimen to well
- 15. Add 4 drops of wash solution
- 16. Positive Negative Read results in 10 -12 minutes
- 17. Reveal G2 CLIA moderate complexity with serum, plasma Reconstitute and refrigerate reagents Screens for HIV-1 Perform test in 5 minutes
- 18. Centrifuge to obtain serum or plasma
- 19. Add buffer to reconstitute conjugate. (Sufficient for 15 tests; Refrigerate to store)
- 20. Add 3 drops buffer to moisten membrane
- 21. Add one drop of serum or plasma, followed by 3 drops of buffer.
- 22. Add 4 drops of Colorimetric Detection Agent
- 23. Add 3 drops of buffer to wash
- 24. Reactive Negative Read results immediately
- 25. Multispot HIV-1/HIV-2 CLIA moderate complexity with serum, plasma Refrigerate reagents Distinguishes HIV-1 from HIV-2 Perform test in 15 minutes
- 26. Dilution of plasma or serum
- 27. Remove and discard pre-filter
- 28. Several timed reagent & wash steps
- 29. Reactive Recombinant HIV-1 Control Peptide HIV-2 Peptide HIV-1 Negative HIV-1 & HIV-2 Positive
- 30. Remember the tradeoffs… Good News: More HIV-positive people receive their test results. Bad News: Some people will receive a false- positive result before confirmatory testing.
- 31. Interpreting Rapid Test Results For a laboratory test: Sensitivity: Probability test=positive if patient=positive Specificity: Probability test=negative if patient=negative Predictive value: Probability patient=positive if test=positive Probability patient=negative if test=negative
- 32. Example: Test 1,000 persons Test Specificity = 99.6% (4/1000) HIV prevalence = 10% True positive: 100 False positive: 4 Positive predictive value: 100/104 = 96%
- 33. Example: Test 1,000 persons Test Specificity = 99.6% (4/1000) HIV prevalence = 10% True positive: 100 False positive: 4 Positive predictive value: 100/104 = 96% HIV prevalence = 0.4% True positive: 4 False positive: 4 Positive predictive value: 4/8 = 50%
- 34. Positive Predictive Value of a Single Test Depends on Specificity & Varies with Prevalence Predictive Value, Positive Test HIV Prevalence OraQuick Reveal Uni-Gold Single EIA 10% 99% 92% 97% 98% 5% 98% 85% 95% 96% 2% 95% 69% 87% 91% 1% 91% 53% 77% 83% 0.5% 83% 36% 63% 71% 0.3% 75% 25% 50% 60% 0.1% 50% 10% 25% 33% Test Specificity 99.9% 99.1% 99.7% 99.8%
- 35. Routine HIV Screening for Emergency Department Patients OraQuick testing since October 2002 60% accept HIV testing 98% receive test results 2.5% new HIV positive 80% entered HIV care 4 new demonstration projects (Wisconsin, Massachusetts, Los Cook County Hospital, Chicago Angeles, New York)
- 36. Characteristics Rapid Test Positive Patients N=82 No previous test 47 (57%) Risk Factors MSM 29 (34%) IDU 8 (10%) Sex Partner IDU 3 ( 4%) No identified risk 42 (51%)
- 37. HIV Screening in Acute Care Settings New HIV+ Cook County ED, Chicago 2.5% Grady ED, Atlanta 2.7% Johns Hopkins ED, Baltimore 3.2% Massachusetts (4 hospitals) 2.0% HIV testing sites 1.2%
- 38. HIV Screening with OraQuick in Labor and Delivery: the MIRIAD Study Testing of pregnant women in labor for whom no HIV test results are available; 12 hospitals in 5 cities: Atlanta, Chicago, Miami, New Orleans, New York To date 4894 women screened 34 (0.7%) new HIV infections identified 4 false positive OraQuick tests, no false negatives 11 false-positive EIAs: 5 p24 only, 6 WB negative Positive Predictive value: OraQuick 90%; EIA 76% Bulterys et al, JAMA July 2004
- 39. Turnaround Times for Rapid Test Results, Point-of-Care vs Lab Testing Point-of-care testing: median 45 min – (range 30 min – 2.5 hours) Same test in Laboratory: median 3.5 hours – (range 94 min – 16 hours) MMWR 52:36, Sept 16, 2003
- 40. OraQuick Outreach Testing for High- risk Persons: El Paso On-site testing at community sites: Old Plantation night club and mobile van Individual counseling and testing El Paso Gay Community Center and Centro de Salud Familiar la Fe
- 41. OraQuick Fingerstick Results: N = 1275 Preliminary positive 18 (1.4%) True positives 17 (1.3%) False Positives 1 (0.07%) Specificity 1256/1257 (99.9%) Positive Predictive Value 17/18 (94%) All clients received their test results
- 42. OraQuick Outreach to High-risk Persons of Color On-site testing at sites throughout the community Group pretest counseling. Individual testing and post-test counseling. Patrick Keenan MD University of Minnesota Medical School Department of Family Practice and Community Health
- 43. Outreach Testing Sites Chemical Dependency Sex offender groups Programs “Johns” programs Homeless shelters Half-way houses Sex worker support Health fairs program Strip club workers Drop-in center for gay African-born groups youth Drug court support Teen clinic groups Gay bars
- 44. OraQuick Fingerstick Results: N = 1021 Preliminary positive 5 (0.5%) True positives 4 (0.4%) False Positives 1 (0.1%) Sensitivity 4/4 (100%) Specificity 1016/1017 (99.9%) Positive Predictive Value 4/5 (80%)
- 45. Results 99.7% of clients received their test results and post-test counseling. The average time between fingerstick and learning test result was 28 minutes.
- 46. CDC’s OraQuick Procurement & Distribution 527,775 test kits shipped in 2003 and 2004 –137 health depts and CBOs in 36 states Utilization September 2003 – September 2004: – 173,003 persons tested – 2,741 (1.6%) HIV positive – 17,266 devices used for training – 25,926 devices use to run external controls
- 47. Changes in HIV Testing at Same Sites After Rapid Testing Introduced 6000 5222 EIA 5000 Rapid Test Number of Tests 3839 4000 3000 2000 1929 1359 932 1002 1000 666 786 0 02 03 02 03 02 03 02 03 Utah Maryland New York Wisconsin State
- 48. Changes in Positive Tests at Same Sites After Rapid Testing Introduced 60 Number of Positive Tests 50 EIA Rapid Test 40 30 20 10 0 02 03 02 03 02 03 02 03 Utah Maryland New York Wisconsin State
- 49. Results of Confirmatory Testing MMWR March 19, 2004
- 50. Results of Confirmatory Testing 5 patients: •Initial EIA or confirmatory test negative •Some labs did only EIA •HIV-positive on follow-up specimen
- 51. Results of Confirmatory Testing 4 patients: •Initial confirmatory test indeterminate •Early infection, evolving Western blot •HIV-positive on follow-up specimen
- 52. Results of Confirmatory Testing 4 patients: •Initial and follow-up tests negative •False-positive OraQuick rapid test
- 53. Results of Confirmatory Testing 8 patients: •Unsuccessful follow-up •HIV status unconfirmed
- 54. Confirmatory Testing Confirmatory test essential (not just EIA!) For Western blot: Venipuncture for whole blood Oral fluid specimen Follow-up testing of persons with negative or indeterminate Western blot results after 4 weeks
- 55. Additional Resources General and technical information (updated frequently): www.cdc.gov/hiv/rapid_testing