HIV AIDS screening

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-in-Chief: Ujjwal Rastogi, MBBS ; Ammu Susheela, M.D. [2]

Overview

The major determinant of the morbidity and mortality of HIV infections is adequate antiretroviral therapy. For that reason, early detection is essential in improving outcomes. In 2006, the Centers for Disease Control announced an initiative for voluntary, routine testing of all Americans aged 13–64 during health care encounters. An estimated 25% of infected individuals were unaware of their status. Routine prenatal HIV testing was also recommended for all women as part of their normal gestational screening tests.

Who to screen

Everyone

• According to the U.S. guidelines, all sexually active individuals have to be tested at least once for HIV.
• At least annual testing is recommended for those with an ongoing high risk of infection (sexual partners of individuals with sexually transmitted infections, individuals with more than one sexual partner since their most recent HIV test, injection-drug users, and individuals who exchange sex for drugs or money).

Rationale for Routine Screening for HIV Infection

• People who are infected with HIV but not aware of it are not able to take advantage of the therapies that can keep them healthy and extend their lives, nor do they have the knowledge to protect their sex or drug-use partners from becoming infected. Knowing whether one is positive or negative for HIV confers great benefits in healthy decision making.
• Cohort studies have demonstrated that many infected persons decrease behaviors that help transmit infection to sex or needle-sharing partners once they are aware of their positive HIV status.
• HIV-infected persons who are unaware of their infection do not reduce risk behaviors.
• Persons tested for HIV who do not return for test results might even increase their risk for transmitting HIV to partners.
• Early referral to medical care could prevent HIV transmission in communities while reducing a person's risk for HIV-related illness and death, because medical treatment that lowers HIV viral load might also reduce risk for transmission to others.
• Several patients with undiagnosed HIV infection had multiple health care visits before getting an HIV test.
• Approximately 38% of new HIV cases are transmitted by individuals with undiagnosed HIV infection.
• HIV infection is consistent with all generally accepted criteria that justify screening:

1. HIV infection is a serious health disorder that can be diagnosed before symptoms develop.
2. HIV can be detected by reliable, inexpensive, and noninvasive screening tests.
3. Infected patients have years of life to gain if treatment is initiated early, before symptoms develop.
4. The costs of screening are reasonable in relation to the anticipated benefits. Among pregnant women, screening has proven substantially more effective than risk-based testing for detecting unsuspected maternal HIV infection and preventing perinatal transmission.

• The use of “opt-out” testing (i.e., all adults are informed that an HIV test could be done; however, they can opt out if they want) has been shown to be more reliable in detection of HIV cases and cost-effective.

Screening Donors of Blood and Cellular Products

HIV can be transmitted to a person receiving blood or organs from an infected donor. To reduce this risk, blood banks and organ donor programs screen donors, blood, and tissues thoroughly. People who received blood transfusions or clotting products between 1977 and 1985 (before screening for the virus became standard practice) are at highest risk for getting HIV. Basic screening lab tests and regular cervical Pap smears are important to monitor in HIV infection, due to the increased risk of cervical cancer in women with a compromised immune system. Tests selected to screen donor blood and tissue must provide a high degree of confidence that HIV will be detected if present (that is, a high sensitivity is required). A combination of antibody, antigen and nucleic acid tests are used by blood banks in Western countries. The World Health Organization estimated that, inadequate blood screening had resulted in 1 million new HIV infections worldwide. In the USA, since 1985, all blood donations are screened with an ELISA test for HIV-1 and HIV-2, as well as a nucleic acid test. These diagnostic tests are combined with careful donor selection. The risk of transfusion-acquired HIV in the U.S. was approximately one in 2.5 million for each transfusion.

Screening for HIV in Pregnant Women and their Infants^[3]

• Public health services (PHS) recommends that all pregnant women in the United States be tested for HIV infection. All health-care providers should recommend HIV testing to all of their pregnant patients, pointing out the substantial benefit of knowledge of HIV status for the health of women and their infants. HIV screening should be a routine part of prenatal care for all women.
• HIV testing should be voluntary and free of coercion. Informed consent before HIV testing is essential. Information regarding consent can be presented orally or in writing and should use language the client understands. Accepting or refusing testing must not have detrimental consequences to the quality of prenatal care offered. Documentation of informed consent should be in writing, preferably with the client's signature. State or local laws and regulations governing HIV testing should be followed. HIV testing should be presented universally as part of routine services to pregnant women, and confidential informed consent should be maintained.
• Although HIV testing is recommended, women should be allowed to refuse testing. Women should not be tested without their knowledge.
• Women who refuse testing should not be coerced into testing, denied care for themselves or their infants, or threatened with loss of custody of their infants or other negative consequences.
• Discussing and addressing reasons for refusal (e.g., lack of awareness of risk or fear of the disease, partner violence, potential stigma, or discrimination) could promote health education and trust-building and allow some women to accept testing at a later date.
• Women who refuse testing because of a previous history of a negative HIV test should be informed of the importance of retesting during pregnancy. All logistical reasons for not testing (e.g., scheduling) should be addressed as well. Health-care providers should remember that some women who initially refuse testing might accept at a later date, particularly if their concerns are discussed.
• Some women who refuse confidential testing might be willing to obtain anonymous testing. However, they should be informed that if they choose anonymous testing, no documentation of the results will be recorded in the medical chart, and their providers might have to retest them, potentially delaying provision of antiretroviral drugs for therapy or perinatal prophylaxis. Some women will continue to refuse testing, and their decisions should be respected.
• Before HIV testing, health-care providers should provide the following minimum information. Although a face-to-face counseling session is ideal, other methods can be used (e.g., brochure, pamphlet, or video) if they are culturally and linguistically appropriate.
  • HIV is the virus that causes AIDS. HIV is spread through unprotected sexual contact and injection-drug use. Approximately 25% of HIV-infected pregnant women who are not treated during pregnancy can transmit HIV to their infants during pregnancy, during labor and delivery, or through breast feeding.
  • A woman might be at risk for HIV infection and not know it, even if she has had only one sex partner.
  • Effective interventions (e.g., highly active combination antiretrovirals) for HIV-infected pregnant women can protect their infants from acquiring HIV and can prolong the survival and improve the health of these mothers and their children.
  • For these reasons, HIV testing is recommended for all pregnant women.
  • Services are available to help women reduce their risk for HIV and to provide medical care and other assistance to those who are infected.
  • Women who decline testing will not be denied care for themselves or their infants.
• Health-care providers should perform HIV testing in consenting women as early as possible during pregnancy to promote informed and timely therapeutic decisions. Retesting in the third trimester, preferably before 36 weeks of gestation, is recommended for women known to be at high risk for acquiring HIV (e.g., those who have a history of sexually transmitted diseases [STDs], who exchange sex for money or drugs, who have multiple sex partners during pregnancy, who use illicit drugs, who have sex partner[s] known to be HIV-positive or at high risk, and who have signs and symptoms of seroconversion). Routine universal retesting in the third trimester may be considered in health-care facilities with high HIV seroprevalence among women of childbearing age. Retesting for syphilis during the third trimester and again at delivery also is recommended for pregnant women at high risk. [4]
• Some states mandate syphilis screening at delivery for all pregnant women.
• Women admitted for labor and delivery with unknown or undocumented HIV status should be assessed promptly for HIV infection to allow for timely prophylactic treatment. Expedited testing by either rapid return of results from standard testing or use of rapid testing (with confirmation by a second licensed test when available) is recommended for these women. The goal is to identify HIV-infected women or their infants as soon as possible because the efficacy of prophylactic therapy is greatest if given during or as soon after exposure as possible (i.e., within 12 hours of birth). Informed consent is essential for women tested prenatally, and women in labor with unknown status should

be allowed to refuse testing without undue consequences. After delivery, standard confirmatory testing should be done for women with positive rapid test results.

• Regulations, laws, and policies regarding HIV screening of pregnant women and infants are not standardized throughout all states and U.S. territories. Health-care providers should be familiar with and adhere to state/local laws, regulations, and policies concerning HIV screening of pregnant women and infants.
• Routine prenatal HIV testing with streamlined counseling and consent procedures has increased the number of pregnant women tested substantially.

Selection of tests to screen

Per the United States Preventive Services Task Force (USPSTF):

• "Current CDC guidelines recommend testing for HIV infection with an antigen/antibody immunoassay approved by the US Food and Drug Administration that detects HIV-1 and HIV-2 antibodies and the HIV-1 p24 antigen, with supplemental testing following a reactive assay to differentiate between HIV-1 and HIV-2 antibodies. If supplemental testing for HIV-1/HIV-2 antibodies is nonreactive or indeterminate (or if acute HIV infection or recent exposure is suspected or reported), an HIV-1 nucleic acid test is recommended to differentiate acute HIV-1 infection from a false-positive test result."

Ethics of HIV Screening

The UNAIDS/WHO policy statement on HIV Testing states that conditions under which people undergo HIV testing must be anchored in a human rights approach that pays due respect to ethical principles. According to these principles, the conduct of HIV testing of individuals must be

• Confidential.
• Accompanied by counseling (for those who test positive).
• Conducted with the informed consent of the person being tested.

Confidentiality

Considerable controversy exists over the ethical obligations of health care providers to inform the sexual partners of individuals infected with HIV that they are at risk of contracting the virus. Some legal jurisdictions permit such disclosure, while others do not. More state funded testing sites are now using confidential forms of testing. This allows for monitoring of infected individuals easily, compared to anonymous testing that has a number attached to the positive test results. Controversy exists over privacy issues.

In developing countries, home-based HIV testing and counseling (HBHTC) is an emerging approach for addressing confidentiality issues. HBHTC allows individuals, couples, and families to learn their HIV status in the convenience and privacy of their home environment. Rapid HIV tests are most often used, so results are available for the client between 15 and 30 minutes. Furthermore, when an HIV positive result is communicated, the HTC provider can offer appropriate linkages for prevention, care, and treatment.

Anonymous Testing

Testing that has only a number attached to the specimen that will be delivered for testing. Items that are confirmed positive will not have the HIV infected individual's name attached to the specimen. Sites that offer this service advertise this testing option.

Evaluation and Screening in Patients with HIV Infection

At the Time of Diagnosis

• History taking
• Physical examination
• Screening test for HIV antibody and antigen,
• Measurement of HIV RNA (viral load), CD4 count, and assessment of HIV resistance genotype if ART initiated at time and place of diagnosis or if acute HIV seroconversion suspected
• Liver and kidney function tests
• Complete blood count (CBC) with differential
• Initiation of prophylaxis against Pneumocystis jiroveci pneumonia, if P. jiroveci pneumonia clinically suspected
• Screening for sexually transmitted infection

At First Clinic Visit

• History taking
• Physical examination
• Measurement of HIV RNA (viral load), CD4 count, and assessment of HIV resistance genotype are not needed if ART initiated at time and place of diagnosis
• Assessment of resistance to ART
• Liver and kidney function tests
• Complete blood count (CBC) with differential
• Serum lipid profile
• Urinanalysis
• HBV and HCV serologic tests
• Pregnancy test if the woman in the childbearing age
• Prophylaxis against Pneumocystis jiroveci pneumonia when CD4 count is <200 cells/mm3
• Cryptococcal antigen screening if CD4 counts <100 cells/mm3
• Urine test for histoplasmosis antigen if CD4 count <100 cells/mm3 in areas where histoplasmosis endemic
• Screening for sexually transmitted infection
• Testing for HLA-B*5701 before prescribing abacavir
• Tropism assay (CCR5) before prescribing maraviroc
• Assessment of psychosocial factors (substance abuse, alcohol abuse, depression, anxiety, suicidality, housing, food insecurity, domestic violence)

At Subsequent Visits

• History taking
• Physical examination
• Measurement of HIV RNA (viral load)
• CD4 count every 6 months until HIV RNA sustained (<100 copies/ml) for 1 year and CD4 >250 cells/mm3; then no longer check is needed
• Liver and kidney function tests
• Complete blood count (CBC) with differential
• Serum lipid profile
• Urinanalysis
• HBV or HCV if any unexplained increase in serum AST or ALT level or annually in patients who remain at high risk for infection or reinfection (high-risk sexual exposure or ongoing injection drug use).
• Pregnancy test if the woman in the childbearing age
• Screening for sexually transmitted infection
• Annual evaluation for cervical cancer/anal cancer with pap smears, if available or at least digital rectal examination (DRE)
• Assessment of psychosocial factors (medication adherence, substance abuse, alcohol abuse, depression, anxiety, suicidality, housing, food insecurity, domestic violence, social isolation, polypharmacy)

• Assessment of cognitive function in patients older than 60 year of age or as indicated clinically, every 2 years

With Regimen Change

• History taking
• Physical examination
• Measurement of HIV RNA (viral load), CD4 count, and assessment of HIV resistance genotype at time of confirmed virologic failure (detectable viremia)
• Assessment of resistance to ART at time of confirmed virologic failure (detectable viremia)
• Liver and kidney function tests
• Complete blood count (CBC) with differential
• Initiation of prophylaxis against Pneumocystis jiroveci pneumonia in case of virologic failure
• Cryptococcal antigen screening, each year
• Assessment for medication adherence