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Routine HIV Screening in Health Care Settings David Spach, MD Clinical Director Northwest AIDS Education and Training Center Professor of Medicine, Division.

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Presentation on theme: "Routine HIV Screening in Health Care Settings David Spach, MD Clinical Director Northwest AIDS Education and Training Center Professor of Medicine, Division."— Presentation transcript:

1 Routine HIV Screening in Health Care Settings David Spach, MD Clinical Director Northwest AIDS Education and Training Center Professor of Medicine, Division of Infectious Diseases University of Washington Seattle This project was funded under cooperative agreement number U65/PS from the Centers for Disease Control and Prevention (CDC). HIV Diagnostic Testing

2 Types of HIV Diagnostic Tests Initial and Supplemental HIV Tests Sensitivity and Specificity of HIV Tests Laboratory-Based HIV Testing Algorithms Point-of-Contact (Rapid) HIV Testing Algorithms Diagnosis of Acute HIV

3 HIV Diagnostic Testing Types of HIV Diagnostic Tests Initial and Supplemental HIV Tests Sensitivity and Specificity of HIV Tests Laboratory-Based HIV Testing Algorithms Point-of-Contact (Rapid) HIV Testing Algorithms Diagnosis of Acute HIV

4 Types of HIV Diagnostic Tests HIV Antibodies HIV-1 RNA HIV p24 Antigen Most Common Test for Established Infection Rarely Used Future use: 4 th Generation EIA Used for Acute HIV and Indeterminate WB

5 HIV Diagnostic Testing Types of HIV Diagnostic Tests Initial and Supplemental HIV Tests Sensitivity and Specificity of HIV Tests Laboratory-Based HIV Testing Algorithms Point-of-Contact (Rapid) HIV Testing Algorithms Diagnosis of Acute HIV

6 Initial and Supplemental HIV Tests Initial Test - Enzyme Immunoassay (EIA) - Chemiluminescent Immunoassay (CIA) Supplemental Tests - Western blot - Indirect Immunofluorescence Assay (IFA) - Qualitative HIV-1 RNA

7 Initial and Supplemental HIV Tests Initial Test - Enzyme Immunoassay (EIA) - Chemiluminescent Immunoassay (CIA) Supplemental Tests - Western blot - Indirect Immunofluorescence Assay (IFA) - Qualitative HIV-1 RNA

8 Generation of EIA Tests First Second Third*Fourth Uses crude viral lysate Detects IgM and IgG in “Sandwich” EIA Uses recombinant HIV antigens or peptides Detects HIV antibodies and p24 antigen *Not US FDA-approved as of 10/1/09

9 Traditional HIV EIAs Based on color change/fluorescence Change compared with standardized cut-off Result positive or negative No specific antibody reaction information Multiple samples run with traditional EIA Based on color change/fluorescence Change compared with standardized cut-off Result positive or negative No specific antibody reaction information Multiple samples run with traditional EIA 96-Well Microtiter Plate EIAInterpretation of EIAs

10 HIV-1 Western Blot Antigens p = protein gp = glycoprotein Number = molecular weight

11 Components Used in HIV-1 Western Blot Human HIV Antibodies (from patient serum) YYYY HIV Western blot Strip YY HIV Antigens (on Western blot) YYY Antihuman IgG Antibodies Enzyme Detector Color Reagent

12 Sample HIV-1 Western Blot Y Y Y YY Y Y Y YY Y Y Antibodies to gp120 Anti-human IgG Enzyme Detector HIV gp120 antigen Color Reagent Antibodies to p24 Enzyme Detector HIV p24 antigen Color Reagent Anti-human IgG Test Completed gp120 & p24 bands Visible

13 HIV-1 Gene Products & Western Blot

14 HIV-1 and HIV-2 Gene Products & Western Blot

15 Interpretive Criteria for HIV-1 Western Blot Source: CDC. MMWR. 1989:38(S-7):1-7. Positive Control

16 Interpretive Criteria for HIV-1 Western Blot Source: CDC. MMWR. 1989:38(S-7):1-7. Negative No bands:

17 Interpretive Criteria for HIV-1 Western Blot Source: CDC. MMWR. 1989:38(S-7):1-7. Positive At least two of the following bands: p24 gp41 gp120/160

18 Interpretive Criteria for HIV-1 Western Blot Source: CDC. MMWR. 1989:38(S-7):1-7. Indeterminate One or more bands present Not meeting positive criteria Examples Most common bands seen with indeterminate Western blot (IWB) p17, p24, p55

19 HIV Diagnostic Testing Types of HIV Diagnostic Tests Initial and Supplemental HIV Tests Sensitivity and Specificity of HIV Tests Laboratory-Based HIV Testing Algorithms Point-of-Contact (Rapid) HIV Testing Algorithms Diagnosis of Acute HIV

20 Sensitivity Probability that test is positive if person is infected HIV Antibody Test: Sensitivity

21 Persons Infected with HIV: n = 50 Example

22 HIV Antibody Test: Sensitivity HIV Antibody Testing: 49/50 PositivePersons Infected with HIV: n = 50 Example

23 HIV Antibody Test: Sensitivity HIV Antibody Testing: 49/50 PositivePersons Infected with HIV: n = 50 Sensitivity = 49/50 = 98% Example

24 Sensitivity of HIV Antibody Tests Used in US HIV Antibody Tests Sensitivity >> 99%

25 HIV Antibody Test: False Negative HIV Antibody TestingHIV-Infected Persons Example

26 HIV Antibody Test: False Negative HIV Antibody TestingHIV-Infected Persons False Negative Example

27 Some Causes of False-Negative Antibody Tests Acute HIV Infection Advanced HIV Infection Antiretroviral Therapy

28 Specificity Probability that test is negative if person is not infected HIV Antibody Test: Specificity

29 Persons NOT Infected with HIV: n = 50 Example

30 HIV Antibody Test: Specificity HIV Antibody Testing: 48/50 NegativePersons NOT Infected with HIV: n = 50 Example

31 HIV Antibody Test: Specificity HIV Antibody Testing: 48/50 NegativePersons NOT Infected with HIV: n = 50 Specificity = 48/50 = 96% Example

32 HIV Antibody Test: False Positive HIV Antibody TestingPersons NOT Infected with HIV Example

33 HIV Antibody Test: False Positive HIV Antibody TestingPersons NOT Infected with HIV False Positive Example

34 Specificity of HIV Antibody Tests Used in US Initial HIV Antibody Tests Specificity > 98% Supplemental HIV Test (if initial test positive) Specificity >> 99%

35 HIV Antibody Test: Specificity True Infection False Positive False Positives: proportion of false-positive tests increases in populations with low HIV prevalence

36 Causes of False-Positive HIV Antibody Tests Other Viral Diseases Hematologic Disorders Liver Disease Immunizations Autoimmune Disorders

37 Interpreting Test Results Sensitivity: Probability test = positive IF person = positive Specificity: Probability test = negative IF person = negative Positive Predictive Value: Probability person = positive IF test = positive Negative Predictive Value: Probability person = negative IF test = negative

38 Positive Predictive Value of HIV Tests in Populations with Differing HIV Prevalence Example: HIV Testing 1,000 Persons

39 HIV Diagnostic Testing Types of HIV Diagnostic Tests Initial and Supplemental HIV Tests Sensitivity and Specificity of HIV Tests Laboratory-Based HIV Testing Algorithms Point-of-Contact (Rapid) HIV Testing Algorithms Diagnosis of Acute HIV

40 General Approach to HIV Diagnostic Testing Supplemental Initial Optimized for Sensitivity Optimized for Specificity

41 1989 CDC/ASTPHLD HIV Testing Algorithm InitialSupplemental EIA Western blot or IFA Repeatedly Reactive Source: CDC. MMWR. 1989;38(S-7):1-7.

42 Modern HIV Testing Algorithms Source: CDC. MMWR. 2001;50(RR19):1-58. Initial Laboratory-Based Approach to HIV Testing Point-of-Contact Approach to HIV Testing Point-of-Contact Approach to HIV Testing Diagnosing Acute HIV

43 HIV Testing Algorithms

44 HIV Testing Algorithms

45 Laboratory-Based HIV Testing Algorithms Initial HIV Negative Nonreactive HIV-1/HIV-2 Immunoassay* *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

46 Laboratory-Based HIV Testing Algorithms Initial Reactive Repeat Testing (in duplicate) HIV-1/HIV-2 Immunoassay* *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

47 Laboratory-Based HIV Testing Algorithms Initial Reactive Repeat Testing (in duplicate) HIV Negative Both Nonreactive HIV-1/HIV-2 Immunoassay* *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

48 Laboratory-Based HIV Testing Algorithms Initial Reactive Repeat Testing (in duplicate) Repeatedly Reactive Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1/HIV-2 Immunoassay* *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

49 Laboratory-Based HIV Testing Algorithms Initial Reactive Repeat Testing (in duplicate) Repeatedly Reactive Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1/HIV-2 Immunoassay* HIV Negative Negative *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

50 Laboratory-Based HIV Testing Algorithms Initial Reactive Repeat Testing (in duplicate) Repeatedly Reactive Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1/HIV-2 Immunoassay* HIV Negative Negative Test for HIV-2 with any of Following: Indicated by local HIV-2 prevalence Indicated by travel or risk history Indicated by clinical presentation *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

51 Laboratory-Based HIV Testing Algorithms Initial Reactive Repeat Testing (in duplicate) Repeatedly Reactive Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1/HIV-2 Immunoassay* Positive HIV Infected *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

52 Laboratory-Based HIV Testing Algorithms Initial Reactive Repeat Testing (in duplicate) Repeatedly Reactive Supplemental HIV-1/HIV-2 Immunoassay* Indeterminate HIV-1 Western blot *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

53 Approach to Indeterminate Western blot HIV-1 Western blot Indeterminate

54 Approach to Indeterminate Western blot HIV-1 Western blot Repeat HIV-1 Western blot after 2-4 Weeks HIV RNA Test or Indeterminate

55 Modern Approach to Indeterminate Western blot Source: CDC. MMWR. 2001;50(RR19):1-58. Indeterminate (no recent exposure) HIV-1 Western blot HIV Infected Not HIV Infected Repeat HIV-1 Western blot after 2-4 Weeks HIV RNA Test or Indeterminate

56 Modern Approach to Indeterminate Western blot HIV Infected HIV-1 Western blot Repeat HIV-1 Western blot after 2-4 Weeks HIV RNA Test or Indeterminate Not HIV Infected Indeterminate (no recent exposure)

57 Modern Approach to Indeterminate Western blot Not HIV Infected HIV Infected HIV-1 Western blot Repeat HIV-1 Western blot after 2-4 Weeks HIV RNA Test or Indeterminate Indeterminate (RECENT EXPOSURE ) Further Evaluation Needed Indeterminate (RECENT EXPOSURE ) Further Evaluation Needed

58 Approach to Indeterminate Western blot HIV-1 Western blot HIV Infected Not HIV Infected Repeat HIV-1 Western blot after 2-4 Weeks HIV RNA Test or Indeterminate Indeterminate (no recent exposure)

59 HIV Diagnostic Testing Types of HIV Diagnostic Tests Initial and Supplemental HIV Tests Sensitivity and Specificity of HIV Tests Laboratory-Based HIV Testing Algorithms Point-of-Contact (Rapid) HIV Testing Algorithms Diagnosis of Acute HIV

60 Point of Contact (Rapid) Tests Uni-Gold Recombigen Multispot HIV-1/HIV-2Clearview Complete HIV 1/2 Oraquick Advance HIV-1/2Reveal G3Clearview HIV 1/2 Stat Pak

61 Point of Contact (Rapid) HIV Tests FDA-Approved Tests in US, August 2009

62 Point of Contact (Rapid) HIV Testing Algorithms Nonreactive Rapid Test Source: CDC. MMWR. 2004;53(10):221-2.

63 Point of Contact (Rapid) HIV Testing Algorithms Source: CDC. MMWR. 2004;53(10): HIV Negative Nonreactive Rapid Test Client considered HIV-negative unless recent exposure to HIV has occurred

64 Point of Contact (Rapid) HIV Testing Algorithms Source: CDC. MMWR. 2004;53(10): Rapid Test Reactive Preliminary Positive Counsel Client that HIV has not been Confirmed Follow-Up Supplemental Testing is Necessary

65 Point of Contact (Rapid) HIV Testing Algorithms Rapid Test Reactive Preliminary Positive Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA Source: CDC. MMWR. 2004;53(10):221-2.

66 Point of Contact (Rapid) HIV Testing Algorithms Source: CDC. MMWR. 2004;53(10): Rapid Test Reactive Preliminary Positive Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA EIA CIA Optional EIA or CIA testing optional Perform supplemental testing regardless of EIA or CIA result EIA = Enzyme Immunoassay CIA= Chemiluminescent Immunoassay

67 Point of Contact (Rapid) HIV Testing Algorithms Initial Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA Positive HIV Infected Rapid Test Reactive Preliminary Positive EIA CIA Optional Source: CDC. MMWR. 2004;53(10):221-2.

68 Point of Contact (Rapid) HIV Testing Algorithms Source: CDC. MMWR. 2004;53(10): Rapid Test Reactive Preliminary Positive Follow-up repeat supplemental testing 4 weeks after original reactive Rapid Test Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA Non-Reactive Indeterminate or

69 Point of Contact (Rapid) HIV Testing Algorithms Source: CDC. MMWR. 2004;53(10): Rapid Test Reactive Preliminary Positive Repeat Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA Follow-up repeat supplemental testing 4 weeks after original reactive Rapid Test Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA Non-Reactive Indeterminate or 4 weeks

70 Point of Contact (Rapid) HIV Testing Algorithms Initial Reactive HIV-1/HIV-2 Immunoassay* Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA

71 Point of Contact (Rapid) HIV Testing Algorithms Initial Reactive Repeat Testing (in duplicate) HIV Negative Both Nonreactive HIV-1/HIV-2 Immunoassay* *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

72 Point of Contact (Rapid) HIV Testing Algorithms Initial Reactive Repeat Testing (in duplicate) Repeatedly Reactive Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1/HIV-2 Immunoassay* *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

73 Point of Contact (Rapid) HIV Testing Algorithms Initial Reactive Repeat Testing (in duplicate) Repeatedly Reactive Supplemental HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1 Western blot or HIV-1 IFA or HIV-1 RNA HIV-1/HIV-2 Immunoassay* HIV Negative Negative *Enzyme Immunoassay (EIA) or Chemiluminescent Immunoassay (CIA)

74 HIV Diagnostic Testing Types of HIV Diagnostic Tests Initial and Supplemental HIV Tests Sensitivity and Specificity of HIV Tests Laboratory-Based HIV Testing Algorithms Point-of-Contact (Rapid) HIV Testing Algorithms Diagnosis of Acute HIV

75 Diagnosing Acute HIV HIV RNA levels abruptly rise within several weeks after acute infection Infection HIV RNA

76 Diagnosing Acute HIV HIV RNA “spike” precedes production of detectable HIV antibodies Infection HIV RNA Antibody Titer Detectable Antibody

77 Diagnosing Acute HIV: Eclipse Period Eclipse Period = Time between infection and detectable HIV RNA Infection HIV RNA

78 Diagnosing Acute HIV: Window Period Window Period = Time between infection and detectable HIV antibodies Infection Antibody Titer Detectable Antibody Window Period

79 Modified from: Branson BM. Clin Infect Dis. 2007;5:S Timing of Diagnostic Tests after Initial HIV Infection HIV RNA Detectable HIV EIA* Western blot HIV EIA* 3 rd Generation, IgM-Sensitive EIA 2 nd Generation EIA Viral Lysate EIA HIV EIA* 3 rd Generation, IgM-Sensitive EIA 2 nd Generation EIA Viral Lysate EIA Weeks after HIV Infection

80 Timing of Diagnostic Tests after Initial HIV Infection Modified and Reproduced with permission from American Society of Microbiology Source: Owen SM, et al. J Clin Microbiol. 2008;46:

81 Timing of Diagnostic Tests after Initial HIV Infection Source: Owen SM, et al. J Clin Microbiol. 2008;46: Modified and Reproduced with permission from American Society of Microbiology

82 Timing of Diagnostic Tests after Initial HIV Infection Source: Owen SM, et al. J Clin Microbiol. 2008;46: Modified and Reproduced with permission from American Society of Microbiology

83 Timing of Diagnostic Tests after Initial HIV Infection Source: Owen SM, et al. J Clin Microbiol. 2008;46: Modified and Reproduced with permission from American Society of Microbiology

84 Timing of Diagnostic Tests after Initial HIV Infection Source: Owen SM, et al. J Clin Microbiol. 2008;46: Rapid HIV HIV-1 RNA Modified and Reproduced with permission from American Society of Microbiology

85 Diagnosing Acute HIV: Acute HIV Acute HIV = patients may present with acute retroviral syndrome/illness Acute HIV Infection Antibody Titer Detectable Antibody HIV RNA

86 Source: Vanhems P, et al. AIDS. 2000;14: Signs and Symptoms of 160 Patients with Acute HIV Diagnosing Acute HIV: Clinical Manifestations

87 Laboratory Diagnosis of Acute HIV Acute HIV Infection Antibody Titer Detectable Antibody HIV RNA Positive HIV-1 RNA Assay Negative HIV Antibody Test Positive HIV-1 RNA Assay Negative HIV Antibody Test

88 Acknowledgement The project was funded under cooperative agreement number U65/PS from the Centers for Disease Control and Prevention (CDC).


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