Rapid HIV Testing

July 2006

Chapter Contents

Background

Clients and Settings for Rapid Testing

Rapid HIV Tests

Interpreting Rapid Test Results

Information for the Client

Follow-Up for Results of Confirmatory Tests

Patient Education

References

Table 1. FDA-Approved Rapid HIV Antibody Screening Tests

Background

It is estimated that as many as 300,000 individuals in the United States are unaware that they have HIV infection. It is also estimated that about 25% of these individuals account for approximately 55% of the 40,000 new infections occurring in the United States each year. Studies have shown that once individuals learn about their HIV infection, they substantially reduce their high-risk sexual behaviors. However, even when people are tested for HIV with standard HIV tests, many do not return to obtain the results. With rapid HIV testing, clients can receive their results during the same visit. A rapid test can allow referrals for urgent treatment, such as in pregnant women, as well as nonurgent referrals to engage patients in medical care. Rapid testing also provides immediate information for making clinical decisions, such as whether to offer postexposure prophylaxis.

Clients and Settings for Rapid Testing

Rapid HIV testing is recommended for settings in which the availability of rapid HIV test results would influence medical care immediately, or HIV prevalence is high but clients are not likely to return for the results of HIV tests. These settings include labor and delivery settings (to allow intervention to reduce the risk of perinatal HIV transmission in women with undocumented or unknown HIV status) as well as hospital emergency departments, urgent care and acute care clinics, sexually transmitted disease clinics, drug treatment clinics, and clinical care or testing sites. Rapid HIV testing also is available or being implemented in employee health departments at many hospitals as part of evaluation for and provision of postexposure prophylaxis.

Rapid HIV Tests

The U.S. Food and Drug Administration has approved 4 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. Two rapid tests are approved as CLIA-waived tests, meaning that they may be done 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 done 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.

Interpreting Rapid Test Results

All of the rapid tests are highly sensitive and specific. 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 is almost assuredly not infected, barring recent exposures (sexual contact or needle sharing with an infected person within 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 depends on the specificity of the test and the HIV prevalence in the community. Given the high specificity of the rapid tests (Table 1), this means that if the rapid 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 to be a true positive, but in a population with a low HIV prevalence, that result may be a false positive. For this reason, every positive rapid HIV test is considered a preliminary result and must be confirmed by either Western blot or immunofluorescence assay (IFA).

Information for the Client

Counseling the Client before Testing

Many clients believe the following:

1) they must consent to HIV testing to receive any medical care; or

2) they have been tested while getting medical care, and, because no one informed them otherwise, they must be HIV negative.

Because these assumptions are false, it is important to offer rapid HIV testing as a health screening test, to educate clients 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. When possible, rapid testing should be made available during the current office visit so that clients do not face additional waiting time. The provider should emphasize that a second test is always done to confirm a positive rapid test.

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 sexual 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 done as soon as possible, and schedule a return visit for the results.

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. It is important to start medication to reduce the risk of passing HIV to your baby while we wait for the second (or confirmatory) test 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, patient education should include the following points:

• Rapid HIV testing is an important health screening. Learning that you have HIV infection early can improve your prognosis (can keep you well).
• Knowing that you have HIV infection can help you take precautions to keep from passing HIV to others.
• You can refuse an HIV test, and it will not affect the care you receive.
• The results from the rapid tests are available at the same visit, usually in less than 1 hour.
• If the rapid test is positive, a second, confirmatory test is always done to be sure the rapid test was accurate.
• The rapid test is very accurate--as accurate as the standard HIV test.
• It is important that you come back for the results of the confirmatory test.
• If the test is negative, you do not have HIV infection, but the test may not show recent infection.
• The test results are kept confidential. However, if the confirmatory test is positive, the law requires that the results be reported to the health department (although this may not be the case in certain states). There are places you can go for more information and for counseling, care, or treatment.

References

• Centers for Disease Control and Prevention. Rapid HIV Testing [Web page]. Available online at http://www.cdc.gov/hiv/rapid_testing/. Accessed May 31, 2006.
• Colfax GN, Buchbinder SP, Cornelisse PG, et al. Sexual risk behaviors and implications for secondary HIV transmission during and after HIV seroconversion . AIDS. 2002 Jul 26;16(11):1529-35.
• Glynn M, Rhodes P. Estimated HIV prevalence in the United States at the end of 2003. In: Program and abstracts of the National HIV Prevention Conference-2005; June 12-15, 2005; Atlanta. Abstract T1-B1101.
• Hutchinson AB, Corbie-Smith G, Thomas SR, et al. Understanding the patient's perspective on rapid and routine HIV testing in an inner-city urgent care center . AIDS Educ Prev. 2004 Apr;16(2):101-14.
• Marks G, Crepaz N, Senterfitt JW, et al. Meta-analysis of high-risk sexual behavior in persons aware and unaware they are infected with HIV in the United States: implications for HIV prevention programs . J Acquir Immune Defic Syndr. 2005 Aug 1;39(4):446-53.
• U.S. Preventive Services Task Force. Screening for HIV: recommendation statement . Am Fam Physician. 2005 Dec 1;72(11):2287-92.