HIV Rapid Tests 101: Procurement for VCT Service Delivery Dvora Joseph, HIVAIDS Service Delivery Man

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HIV Rapid Tests 101 Procurement for VCT Service
DeliveryDvora Joseph, HIV/AIDS Service
Delivery ManagerPSI/AIDSMarkPresentation for
PSI ProcurementJuly 8, 2005
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Conventional approach to HIV Testing ELISA

• Enzyme-linked immunoabsorbent assay (ELISA)
• Requires machine to measure color change in test
  wells (spectrophotometer)
• Designed for batch testing (gt100 specimens at a
  time) - can be automated
• Most useful for surveillance and centralized
  blood transfusion testing
• Centralized QA/QC Done at National and Regional
  Laboratories - easy to control
• Obtain informed consent and prepare client for
  HIV testing

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Limitations of ELISA for VCT

• Not flexible (need minimum no. samples filled for
  maximum efficiency)
• Requires specialized equipment (automatic
  pipettes, incubators, washers, test tubes, etc.)
• Requires highly skilled trained technicians to
  perform and read results
• Machine requires maintenance
• Requires venous blood sample and central
  laboratory
• Results can not usually be provided on same-day
  (1-2 week delay often involved)

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Rationale for Development of Rapid HIV Testing
Technology

• The rationale for HIV diagnostic testing has
  changed
• Beginning of Epidemic Clinical confirmation of
  suspected HIV disease
• Present Stage of Epidemic Prevention care
  potential of knowing ones HIV status (VCT
  setting)
• Advent of rapid testing technology has simplified
  HIV testing allowing to move-on-site and away
  from centralized laboratories

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Characteristics of HIV Rapid Tests

• Based on four immunologic principles particle
  agglutination, immunodot, immunofiltration and
  immunochromatography
• Positive test kit result indicated by clumping, a
  spot, a dot or line (visual to naked eye)
• Most rapid tests detect antibodies to both HIV-1
  and HIV-2

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Advantages of Rapid Tests compared to ELISA

• More flexible (efficient for 1 to multiple tests
  at a time)
• Requires minimal equipment and reagents
• Does not require highly trained or skilled staff
• On-site clinic testing can be performed easily
• Very easy to interpret test results (naked eye)
• Samples can obtained less invasively
  (finger-prick) - safer to lab technician
• Same-day screening and confirmation of results
  (available lt30 min.)

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Advantages of Same Day Rapid Test Results

• Lower client travel time and expenses
• Less anxiety during waiting period
• More likely to get same counselor for both pre-
  and post-test counseling
• Client post-test adherence increases dramatically
  (99 compared to 60-80)
• Client VCT intake increases dramatically (500 ?
  in Malawi VCT centers, 1999-2000)
• Facilitates expansion of VCT services in
  resource-constrained settings (remote areas,
  mobile clinics, etc.)

Msowoya K, Marum E et al. Rapid testing and same
day counseling results in huge increase in demand
for for VCT in Malawi. International AIDS
Conference Abstract Durban, 2000.
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HIV Rapid Test Algorithm Development (ANNEXE C)

• Use multiple (up to 3) rapid test kits in
  parallel or in series to maximize positive and
  negative prediction values (required for
  diagnostic purposes)
• Parallel testing Clients are tested using two
  test simultaneously (in parallel) - if tests
  discordant (lt1 occurrence) than a 3rd type of
  rapid test is used (tiebreaker)
• Serial testing Clients test with one rapid test.
  If result is positive, a 2nd different rapid test
  used. Discordant test results are further tested
  with 3rd different type of rapid test (tests done
  in series)

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Advantages of Parallel (vs. Serial) Testing
Algorithm

• Minimize the risk of false negative test result
• Clients perceive that two tests are better than
  one - reduces client shopping around phenomenon
• Can do two rapid tests with one finger-stick
• reduces potential stigma that might result if
  patient called back a second time)
• Shorter clinic waiting times resulting from
  simultaneous testing
• Disadvantage Parallel testing more expensive b/c
  using at least two tests for each client

Adapted from FHI, 2001. Issues in diagnostics
for VCT - Focus on series.
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HIV Rapid Test Algorithm Development (cont.)

• First screening rapid test should be as
  sensitive as possible (minimize false negatives)
• Follow-up confirmatory tests need to be highly
  specific (minimize false positives)
• Use Level 1 complexity test kits - require
  little to no laboratory experience or additional
  equipment and only finger-prick blood
• Selected test kits should be recommended by
  UNAIDS/WHO (see Report of Operational
  Characteristics of Commercially Available HIV
  Tests)

e.g., Determine, Uni-Gold, HemaStrip and Oraquick
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General Outline for Country Evaluation of HIV
Testing Technologies

• Phase I Retrospective evaluation of the
  sensitivity and specificity of selected tests at
  the national reference laboratory
• Phase II Prospective evaluation of the selected
  tests at the regional laboratories
• Phase III Prospective evaluation of selected
  tests at settings where they will most likely be
  used
• NOTE Outline should be adapted upon for specific
  country evaluations

UNAIDS/WHO/CDC. 2001. Guidelines for Using HIV
Testing Technologies in Surveillance.
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VCT Clinic Rapid Test QA/QC

• Ongoing External Quality Control
• Proficiency Testing
• Every month, random 5-10 of total sample load
  (ideally including ve and -ve test results) sent
  to reference laboratory for ELISA testing
  cross-checking
• All rapid test kit algorithm indeterminate
  results confirmed with ELISA testing before
  results provided to client

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Critical Issues for Rapid Test QA/QC

• Use of test kits that have not expired
• Training with the technology being used
• Adherence to manufacturers instructions
• Correct interpretation and transcription of
  results by person reading results

UNAIDS/WHO/CDC. 2001. Guidelines for Using HIV
Testing Technologies in Surveillance.
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PSI Procurement of RTKs

• Approved List of Testing Kit Products and
  Manufacturers as of July 6, 2005
• 12 Highlighted manufacturers make tests that PSI
  countries procure from PSI/W

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PSI PROCUREMENT COUNTRIES AND TEST MANUFACTURERS

• BENIN- ABBOTT, TRINITY (UNIGOLD) AND ORGENICS
• GUYANA- ABBOTT, TRINITY, CHEMBIO, SALIVA
• HONDURAS- ORASURE
• COTE DIVOIRE- ABBOTT, PREMIER MEDICAL
  CORPORATION, TRINITY BIO
• KOSOVO- ABBOTT
• LESOTHO- ABBOTT, ORGENICS, TRINITY BIO-TECH
• MALI- ABBOTT, ORASURE, SALIVA DIAGNOSTICS AND
  CHEMBIO
• MOZAMBIQUE- ABBOTT, TRINITY
• TOGO- ABBOTT AND ORGENICS
• UGANDA- ABBOTT, CARRAMORE, CHEMBIO AND TRINITY
  BIO-TECH
• WCA AMBASSADOR FUND- ABBOTT, ORGENICS
• WEST AFRICA REGION- ABBOTT, ORGENICS, TRINITY
• ZAMBIA- ABBOTT, BIORAD, TRINITY
• 12/13 use Abbott Determine RTKs, all other VCT
  countries do as well

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Questions?See H Drive AIDSMarkRead Only
VCT RTK and Lab for more information.