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Frequently Asked Questions About HIV/AIDS (Part Two)

January 2010

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How Accurate Are Home HIV Tests?

Home HIV tests are as accurate as the antibody tests done in doctors' offices and health departments, and they use the same ELISA/Western Blot/IFA tests. Like other antibody tests, these tests are subject to the same six-month waiting period in order for the tests to be fully accurate.

There are certain pros and cons to using home testing kits.

Pros:

  • A person who's scared about being seen in a clinic can do the test without anyone knowing about it outside their home. They may feel more comfortable doing the test alone.

  • These tests can be ordered by phone or on the Internet, and can be an option for those who do not have transportation to local clinics, or who are home-bound due to disabilities.

  • The test itself is as accurate as antibody tests commonly used in clinics around the country.

Cons:

  • Dealing with test results over the phone can be very difficult, especially if the test was positive. A person can just hang up and never hear all the counseling and information they need to hear. Test counseling is best done face-to-face, and is most effective this way.

  • Using home testing, if a person is positive, there is no way to do partner notification (helping a person's sex/needle-sharing partners know they've been exposed). Partner notification is routinely done by local health departments around the country for HIV and other STDs. Home testing would bypass this important, and proven, preventive health measure.

  • Home testing is also more expensive. Testing through local health departments, and some private agencies, is free or low cost. Home test kits can cost $30 to $50.

  • Another issue to be dealt with is confidentiality. If a person buys a home test kit in a store, everyone in the store will know that person is taking an HIV test. The most confidential way to purchase the kit is by phone or through the Internet. Also, when taking a test at home, all the packaging for the kit has to be well hidden in the garbage. If a garbage man empties your garbage, and sees the test kit packaging in the garbage, they'll know you took an HIV test. If your garbage can were to open up (from animals, wind, etc.) your neighbors could know you've been tested for HIV as well. So for persons taking the home test, I say "Hide Your Garbage!"

    In a home test kit, a person has a test ID card that is used to identify the specimen. Anyone who has the number can get the test result over the phone. The person who is being tested has to make sure that nobody sees the card. Otherwise, any person who sees the card or the number can get that other person's test results. So it's important that a person getting tested at home doesn't leave the ID number lying around the house, where other members of the household can see it.

In the United States, there is presently only one home test kit, Home Access, that has been approved by the U.S. Food and Drug Administration (FDA). There was previously another FDA-approved home test called Confide, but this is no longer being sold, and has been discontinued. The Home Access home HIV test has been proven to be safe to use and accurate. Unfortunately, there are also unapproved home HIV tests being sold illegally, especially over the Internet. The accuracy and safety of these unapproved tests is unknown. Therefore, if you are using a home test kit other than Home Access, I cannot tell you whether these tests are safe or accurate. Like anything else you buy (especially over the Internet), as the saying goes, "Let the buyer beware!"

I personally have tried Home Access. Since I live in a rural community in the United States, I had to be very careful regarding confidentiality, especially as it came to hiding my garbage. Also, I can see some people having difficulty in doing a fingerstick to draw blood for the test. The test itself takes about an hour to do (which includes time for the specimen to dry and to package up the sample to send to the lab). It also includes a lot of reading material for the person to read through. I therefore recommend about two hours to do the test at home. This includes all the time to read the materials, and to do the actual test.

Home testing is an option for those who prefer to do the test on their own without having to go through a doctor or a clinic. It is up to you to decide which option is best for you. I chose to take the test at home, so I would gain a personal insight as to what that was like.


Should I Get a PCR Test or an Antigen Test?

The subject of PCR tests is a very confusing one for many people. Unfortunately, these tests have needlessly been done on many people, and have needlessly contributed to an increase in health-care costs. These tests have their legitimate purposes, as described below, but they are not designed just to make people happy who don't want to wait six months for an antibody test. Taking expensive tests like PCR tests, only needlessly increases our health-care costs even more, thereby further limiting our already limited health-care resources. Expensive tests (like PCR tests) should not be done just to make people happy. They should only be done if there is a legitimate clinical need for these tests.

The DNA qualitative PCR test can be used for diagnostic purposes, but there are limitations to its use. Although it can often pick up an infection after about a month after an exposure, it will not always detect the infection. It is not designed to do routine screening in adults. It is used primarily for:

  • Research applications, where the test can be repeated multiple times to rule out inaccuracies
  • Testing in newborns less than 18 months of age where antibody tests are not reliable
  • Testing in persons with other diseases of the immune system where antibody tests may not be reliable
  • Other unusual circumstances

When we do qualitative diagnostic PCRs, we often do them more than once, just in case the first one did not accurately pick up the infection. We very rarely do just one PCR. We usually do more than one under most circumstances (especially in babies). PCR tests are also usually done in conjunction with other tests for HIV, just to rule out inaccuracies in the test.

This test is very difficult for labs to perform, hence its high cost. The more difficult the test, the greater the chance of inaccuracy. But it's a great test for labs that have a lot of experience with it. Usually only regional reference labs will do this test, but not the vast majority of clinical labs.

Many people have requested these tests, since they don't want to wait six months to take an antibody test. Doing these tests is clinically not necessary in the vast majority of these cases, and only needlessly increases our health care costs (these tests cost several hundred dollars). In the vast majority of cases, antibody tests are all an adult needs. If a person can't cope with the six-month waiting period for antibody testing, counseling is often a better option than PCR testing.

The following is a summary statement about PCR testing that was recently published in a research journal. It states:

"The PCR assay is not sufficiently accurate to be used for the diagnosis of HIV infection without confirmation. Use of PCR for the diagnosis of HIV in adults should be limited to situations in which antibody tests are known to be insufficient. Future studies of PCR performance should be sufficiently large and should use adequate reference standard tests and standardized methods for the performance of PCR. Specimens should be evaluated by persons blinded to clinical status and to the results of other diagnostic tests for HIV infection."

The p-24 antigen test will pick up an infection an average of six days prior to a person testing antibody positive. The p-24 antigen tests will often show positive two to three weeks after initial infection. However, not all recently infected persons have detectable levels of p-24 antigen in their blood.

So a negative p-24 antigen test does not necessarily mean a person is not infected. Once the person turns antibody positive, the p-24 antigen test will often revert back to a negative result. So this test will only be positive for a short period of time.

Let me also stress that the p-24 antigen test alone cannot be used to diagnose HIV infection. Remember, this test will not always pick up an infection. A p-24 antigen test (whether positive or negative) must always be used alongside other HIV diagnostic tests, before a person's HIV status can be determined.


Previous Frequently Asked Questions
More Frequently Asked Questions


Do you want more information on HIV/AIDS, STDs or safer sex? Contact the U.S. Centers for Disease Control Health Line, open 24 hours a day, seven days a week, at 1-800-232-4636. Or visit The Body's Safe Sex and Prevention Forum.

Until next time . . . Work hard, play hard, play safe, stay sober!

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This article was provided by Rick Sowadsky, M.S.P.H..
 
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