HIV Antibody Testing

Rationale and Background Guidelines

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Rationale and Background

Health care personnel in Massachusetts are required by statute to obtain written informed consent from the patient or his/her health care proxy prior to HIV antibody testing. The HIV antibody testing procedure consists of pretest counseling, the test itself, and post-test counseling.

Massachusetts law provides for confidentiality of HIV testing as follows:

"No health care facility...and no physician or health care provider shall (1) test any person for the presence of the HIV antibody or antigen without first obtaining his written informed consent; (2) disclose the results of such test to any person other than the subject thereof without first obtaining the subject's written informed consent; or (3) identify the subject of such test to any person without first obtaining the subject's written informed consent." (M.G.L. c. 111, s. 70F.)

An HIV antibody test can be ordered by a treating physician or authorized HIV counselor. Pretest and post-test counseling is required for all patients. Results should be given in person and never communicated over the telephone or by mail. Information documented in the medical record should include the reason for test, provision of informed consent, the results, dates of test and pretest and post-test counseling, and requesting provider name.

All newly diagnosed cases of HIV infection should be reported to the Massachusetts Department of Public Health.

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Guidelines

Indications

These are divided into historical and clinical categories:

Historical

• men who have sex with men
• people with multiple sexual partners
• current or past injection drug users (IDUs)
• recipients of blood products between 1978 and 1985
• persons with current or past sexually transmitted diseases
• commercial sex workers and their sexual partners
• pregnant women or those of childbearing age who are at risk through drug use, prostitution, or unprotected sex
• children born to HIV-infected mothers
• sexual partners of those at risk for HIV infection
• persons who consider themselves at risk or request testing
• donors of blood products, semen, or organs

Clinical

• tuberculosis
• syphilis
• recurrent shingles
• unexplained chronic constitutional symptoms
• unexplained chronic generalized adenopathy
• unexplained chronic diarrhea or wasting
• unexplained encephalopathy
• unexplained thrombocytopenia
• thrush or chronic/recurrent vaginal candidiasis
• HIV-associated opportunistic diseases, such as pneumocystis pneumonia and Kaposi's sarcoma

In persons with suspected primary HIV syndrome or recently acquired HIV infection (less than three months prior, an HIV antibody test should be performed for baseline information, but supplemental testing (e.g., HIV viral load) is necessary for early diagnosis. Low titer false-positive HIV viral load assays have been reported in persons with acute non-HIV-related illness, so caution is advised in their interpretation.

Contraindications

• inability of patient to understand implications of test result
• acute psychosis
  
• major depression or suicidality
  
• lack of adequate personal support system
  

Potential Benefits and Risks

• individual health benefits include antiretroviral therapy, prophylaxis for opportunistic infections, screening and prophylaxis for tuberculosis, screening for and treatment of syphilis and other sexually transmitted diseases, administration of appropriate vaccinations, and institution of other health care maintenance measures
  
• public health benefits include reduction of high-risk behaviors and monitoring of HIV infection epidemiology
  
• risks include false-positive test result, false-negative test result, adverse psychological reactions, breach of confidentiality, and social discrimination
  

Pretest Counseling

Pretest counseling should include the following:

• distinction between anonymous and confidential testing, and the availability of home testing kit
  
• review of natural history of HIV infection
  
• review of reasons for testing and expectations
  
• review of individual risk behaviors and risk reduction measures
  
• discussion of meaning of positive and negative results
  
• assessment of personal and social supports
  

Testing Procedure

• HIV antibody testing is performed by using an enzyme-linked immunosorbent assay (ELISA), which is a highly sensitive screening test
  
• if this result is negative, the HIV antibody test is reported as negative
  
• if this result is positive, the ELISA is repeated
  
• if the repeat test is positive, a Western blot (WB) assay, which is more specific, is performed for confirmation
  
• if WB assay result is positive, the HIV antibody test is reported as positive
  
• WB results are occasionally described as indeterminate; in these instances, supplemental testing may be recommended
  
• HIV antibody testing does not reliably detect HIV-2, which is common in West Africa; if suspected by history, an ELISA specific for this type of virus can be requested
  
• a low CD4 cell count is not diagnostic of HIV disease and should never be used in lieu of HIV antibody testing
  
  

Rapid tests that detect HIV antibody within 10 minutes have been developed. These enable clinicians to provide definitive negative and preliminary positive results immediately and may be useful in some settings. A positive rapid HIV antibody test is confirmed with the more specific WB assay.

Post-test Counseling

Post-test counseling should include the following:

• review meaning of test results and implications
• if test result is positive:
  • assess patient's reaction and ability to cope
  • anticipate need for immediate support and close follow-up plan for medical evaluation
• if test result is negative:
  • restate possibility of seroconversion if patient is involved in high risk activities
  • dispel any false beliefs regarding invulnerability or immunity to HIV infection

Risk Reduction Counseling

Risk reduction counseling is an important component of both pretest and post-test counseling. It should include the following advice:

• reduce or limit the number of sexual partners
  
• use latex condoms and spermicide for all sexual activity
  
• detoxification or methadone maintenance program for IDU
  
• always use sterile needles; however, if you do share equipment, make sure it is cleaned with bleach as recommended
  
• do not share personal items such as razors and toothbrushes
  

Special Considerations in Pregnant Women

Zidovudine (ZDV) has been shown to decrease the transmission of HIV from mother to child. AIDS Clinical Trials Unit (ACTG) study 076 demonstrated that treating HIV-infected women with ZDV during the second and third trimesters of pregnancy through delivery and treating the newborn can reduce the risk of vertical transmission by two-thirds. More recent data suggest that other antiretroviral drugs may also be effective in this setting. HIV antibody testing should be recommended to all pregnant women and to women at high risk for HIV infection who are considering pregnancy.

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Comments about these guidelines are welcome and can be sent to the author at hlibman@caregroup.harvard.edu