Clinical Guide > Testing and Assessment > Rapid HIV Testing

Rapid HIV Testing

January 2011

Chapter Contents

Background

About 1.5 million people are thought to be living with HIV in the United States, and it has been estimated that about 20% of these individuals are unaware of their HIV serostatus. Almost 56,000 new HIV infections occur in the United States each year. It is important to identify persons who are infected with HIV, in order both to link them to health care services and to reduce the risk that they will unknowingly transmit HIV to others.

The U.S. Centers for Disease Control and Prevention recommends routine voluntary HIV screening for all adults, adolescents, and pregnant women. Nevertheless, many people are reluctant to be tested. Rapid HIV testing is one tool that makes it much easier for individuals to be tested for HIV and to obtain their test results promptly and reliably. Results of standard HIV tests typically are not available until about 1 week after the test, and clients are required to return for a second visit in order to obtain their results. Because of this, many people do not return to learn their results. With rapid HIV testing, clients can be tested and receive their results during a single visit. Rapid testing can allow immediate referrals to engage patients in medical care; it also makes possible referrals for urgent treatment, such as for pregnant women, and allows quick decisions to be made in a number of clinical situations, such as assessment for postexposure prophylaxis.

Clients and Settings for Rapid Testing

Rapid HIV testing is recommended for use in settings in which the availability of rapid HIV test results would influence medical care immediately, or as a routine screening tool in settings where HIV prevalence is high or clients are not likely to return for the results of HIV tests. These settings include labor and delivery facilities (to allow intervention to reduce the risk of perinatal HIV transmission in women with undocumented or unknown HIV status), prenatal care facilities for women who present late in pregnancy, hospital emergency departments, urgent care and acute care clinics, sexually transmitted infection clinics, drug treatment clinics, hospitals, and other clinical care or testing sites. Rapid HIV testing is being implemented in employee health departments at hospitals as part of evaluation for and provision of postexposure prophylaxis. In addition, rapid testing is becoming common in nonclinical settings in high-risk jurisdictions such as jails and mobile health service vans, and in community outreach programs.

Rapid HIV Tests

The U.S. Food and Drug Administration (FDA) has approved six rapid tests for use in the United States (Table 1). Federal regulations under the Clinical Laboratory Improvement Amendments (CLIA) program categorize tests as waived, moderate complexity, or high complexity. Four rapid tests are approved as CLIA-waived tests, meaning that they may be performed at the point of care after appropriate staff training and with procedures in place to insure quality control. These tests use whole blood or oral fluid and require a few simple steps to perform. Other rapid tests are "nonwaived" tests and must be performed in laboratories. Results for rapid tests performed at the point of care are available in less than 30 minutes; results for those done in a laboratory should be available within 1 hour.

Table 1. FDA-Approved Rapid HIV Antibody Screening Tests

TestSpecimen TypeCLIA CategorySensitivity (95% CI*)Specificity (95% CI*)ManufacturerApproved for HIV-2 Detection

* CI = confidence interval

Adapted from CDC and Health Research and Education Trust (HRET), FDA-Approved Rapid HIV Antibody Screening Tests, February 4, 2008.

OraQuick Advance Rapid HIV-1/2 Antibody TestOral fluidWaived99.3% (98.4-99.7)99.8% (99.6-99.9)OraSure TechnologiesYes
Whole blood (fingerstick or venipuncture)Waived99.6% (98.5-99.9)100% (99.7-100)
PlasmaModerate complexity99.6% (98.9-99.8)99.9% (99.6-99.9)
Uni-Gold Recombigen HIVWhole blood (fingerstick or venipuncture)Waived100% (99.5-100)99.7% (99.0-100)Trinity BiotechNo
Serum/plasmaModerate complexity100% (99.5-100)99.7% (99.3-100)
Reveal G-3 Rapid HIV-1 Antibody TestSerumModerate complexity99.8% (99.2-100)99.1% (98.8-99.4)MedMiraNo
Plasma99.8% (99.0-100)98.6% (98.4-98.8)
MultiSpot HIV-1/HIV-2 Rapid TestSerumModerate complexity100% (99.9-100)99.9% (99.8-100)BioRad LaboratoriesYes, differentiates HIV-1 and HIV-2
Plasma
Clearview HIV 1/2 STAT-PAKWhole blood (fingerstick or venipuncture)Waived99.7% (98.9-100)99.9% (99.6-100)Inverness Medical Professional DiagnosticsYes
Serum, plasmaNonwaived99.7% (98.9-100)99.9% (99.6-100)
Clearview COMPLETE HIV 1/2Whole blood (fingerstick or venipuncture)Waived99.7% (98.9-100)99.9% (99.6-100)Inverness Medical Professional DiagnosticsYes
Serum, plasmaNonwaived

Interpreting Rapid Test Results

All FDA-approved rapid tests are highly sensitive and specific, as shown in Table 1, and are as accurate as a standard enzyme-linked immunosorbent assay (ELISA). The negative predictive value of all rapid HIV tests is close to 100%. This means that a client who receives a negative rapid test result almost assuredly is not infected, barring recent exposures (e.g., sexual contact or needle sharing with an infected person within the past 3 months). A client with a history of recent HIV risk behaviors or possible exposures should repeat the HIV test in the near future, because it may take up to 3 months for HIV antibodies to be detectable after infection with HIV.

The positive predictive value of a single positive rapid HIV test result depends on the specificity of the test and the HIV prevalence in the community. The high specificity of the rapid tests (Table 1) means that, if a test result is positive, the likelihood that a client is truly HIV infected depends on the local HIV prevalence. In a population with a high HIV prevalence, a positive rapid test result is likely a true positive, but in a population with a low HIV prevalence, that result has a greater chance of being a false positive. For this reason, every positive rapid HIV test result is considered a preliminary result and must be confirmed by either Western blot or immunofluorescence assay (IFA), just as a positive standard

Information for the Client

Educating the Client Before Testing

It is important to offer rapid HIV testing as part of a health screening, to educate clients about HIV infection and about the test, and to give them an opportunity to ask questions and to decline testing. The provider should reassure clients that the rapid HIV test is just as accurate as the standard HIV test. The provider should emphasize that a second test always is performed in order to confirm a positive rapid test result. When possible, rapid testing should be made available during a regular office visit so that clients do not face additional waiting time.

Giving Reactive (Preliminary Positive) Rapid Test Results

Example of simple language to use outside labor and delivery settings

The following wording is suggested when the client's rapid test result is positive:

"Your preliminary test result was positive, but we won't know for sure if you are infected with HIV until we get the results from your confirmatory test. In the meantime, you should take precautions to avoid transmitting the virus. This means protecting sex partners from possible exposure (using condoms, for example), not sharing injection drug needles or syringes, and so forth."

Emphasize the importance of a confirmatory test, arrange for the confirmatory test to be performed as soon as possible, and schedule a return visit for the patient to receive the test result.

Language to use in labor and delivery settings

The following wording is suggested when the client's rapid test result is positive:

"Your preliminary HIV screening result was positive. You may have HIV infection. We need to do a second (or confirmatory) test, but it is important to start medication to reduce the risk of passing HIV to your baby while we wait for the result. It is important to delay breast-feeding until we have the second test result."

Follow-Up for Results of Confirmatory Tests

Clinical sites that offer rapid HIV testing should have a protocol for conveying the results of confirmatory HIV tests to clients. Rapid testing sites should either provide this service in-house or have mechanisms in place for referring clients to community-based HIV services. For example, when women have preliminary positive results on tests done during labor and delivery, confirmatory test results may be sent to their obstetrician, but often may be sent to the local health department. These women should be given appointments specifically for receiving their confirmatory test results. Clinicians should be familiar with community resources for referring clients with positive rapid test results. All clients with confirmed positive HIV test results should be referred for HIV care; testing sites should establish reliable referral pathways to qualified HIV care providers.

Patient Education

In general settings and in situations not involving labor and delivery, advise patients of the following:

References