Financial PlanningHealthcare

Understanding HIV tests: Life Insurance Industry

Rapid HIV tests are widely used and accepted within the clinical sector. In fact, various government campaigns actively promote ‘VCT’ (Voluntary Testing and Counselling). VCT utilises Rapid HIV test kits which require only a finger prick of blood. The advantages are turnaround times of 20-30 minutes, and the convenience of no sophisticated laboratory techniques or personnel being required; and, of course, the tests may be administered almost anywhere. Hence, many may ask why Rapid HIV testing is not used within the insurance sector.

In order to understand why the industry continues to use formal blood tests for HIV testing, as opposed to Rapid HIV tests, one needs to understand the fundamental difference between these tests. The first step would be revisit the landscape of HIV testing and how it has evolved in recent years.

The first HIV test was developed in 1985 primarily to detect infection by human immunodeficiency virus type 1 (HIV-1). Since then, there has been a significant increase in the number and variety of HIV tests available, with the more recent tests detecting infection by HIV-1, sub-type O and HIV-2. The most commonly used HIV tests may be broadly classified as screening tests or confirmatory tests. In clinical practice, the most common screening tests are those that detect only HIV antibodies or tests that detect both HIV antibodies and p24 antigen in a single test. In addition, blood banks also use more sophisticated and expensive techniques such as Nucleic Acid Testing (NAT) which screen for HIV viral RNA.

Confirmatory tests include tests such as the Western Blot, Immunofluorescence Assay and DNA/RNA Amplification Tests. These tests are both labour-intensive and extremely expensive.

Therefore, for routine screening of HIV, both within clinical practice and the insurance sector, it makes sense to utilise the common screening tests.

 

Understanding the Screening Tests

 

The laboratory technique that is most commonly used for screening tests is referred to as enzyme-linked immunosorbent assay, abbreviated as ELISA. Over the years, four generations of ELISA have evolved, namely, the First Generation, Second Generation, Third Generation and FourthGeneration ELISA. The first three generations tested for the presence of HIV antibodies only.

What are Antibodies?

HIV antibodies are proteins produced by white blood cells. These proteins or antibodies form part of the immune response. Therefore, they are responsible for assisting us in fighting off the HIV infection. It takes a variable number of days to weeks for the immune system to produce a sufficient number of antibodies. This time period differs from person to person; however, most people will develop detectable antibodies within two to eight weeks (the average is 25 days). This time period is referred to as the window period, where an HIV test may be reported as negative, despite the person being infected with HIV. Of course, this simply means that the body has not yet mounted an immune response therefore antibodies are not detectable.

This is why, following a negative ELISA, a healthcare practitioner will encourage a patient to return after three months to retest. This is to ensure that a positive result was not missed because the person was within the window period.

The latest generation of ELISA, called the fourth Generation ELISA, has effectively reduced the problem of the window period by incorporating into the test the p24 antigen. Therefore, the Fourth Generation Test detects both antibodies to the HI virus and the P24 Antigen.

What is the P24 Antigen?

Antigens are the substances found on the viruses, bacteria or other foreign organisms that enter our body. Antigens are responsible for triggering the production of antibodies in the body. The antigen on the HI virus which most commonly provokes an antibody response is the protein P24.

When the HI virus enters the cells of the human body, there is an initial explosion of viral replication. Therefore, since the P24 antigen sits on the HI virus early in HIV infection, P24 antigen may be detected in blood tests. The P24 antigen is often detected earlier than antibodies to HIV, since it does not depend on the body’s production, but is actually found on the HI virus itself.

With the latest Fourth Generation HIV test incorporating the P24 Antigen, this effectively means that obtaining a diagnosis of HIV during the window period is more likely. This is because it tests for both antibodies and P24 Antigen. Therefore, the Fourth Generation ELISA has reduced the window period from three months to an average of 10 days.

Within the insurance sector, the Fourth Generation HIV test is currently considered the first line test for initial screening of applicants. If the Fourth Generation delivers a positive or low-reactive result, then the ThirdGeneration is used to double check the results. Both the Third and Fourth Generation ELISA tests are comparable in terms of sensitivity and specificity, with close to 100% and 99% respectively. This is, of course, manufacturer-dependant. Sensitivity may be defined as the percentage of the results that will be positive when HIV is present. Specificity may be defined as the percentage of the results that will be negative when HIV is not present.

As with most blood tests, formal HIV blood tests require a qualified nurse, phlebotomist or doctor withdrawing a vial of blood. The blood must be appropriately stored and transported to the laboratory. The turnaround times for delivery of results may be anything from 24 hours to a week. This brings us to the question of why Rapid HIV tests are not used more extensively within the industry given the obvious advantages.

Rapid HIV test

The Rapid Test HIV test may also be considered a screening test; however, rapid tests are non-formal blood tests, simply because they can rely on blood taken from a finger prick, oral mucous or even urine. Results are often available within 20-30 minutes. The sensitivity of the Rapid Tests is comparable to the ELISA Third/FourthGeneration. In fact, many researchers report a >99% sensitivity and specificity for various Rapid Test Kits (again manufacturer-dependant).

 

So why does the insurance industry not use Rapid HIV Tests?

From a business perspective, the disadvantage of the currently available Rapid Tests is that they detect only HIV antibodies and not the P24antigen. Thus, this makes them less suitable for the detection of early, primary HIV infection.

Subsequently, Rapid Tests have a reduced ability to detect those individuals within the window period as compared to the Fourth Generation ELISA. This, of course, would be a very strong reason to preclude its current use within the insurance industry (three months versus 10 days with the Fourth Generation ELISA).

Nevertheless, in a country such as ours, we cannot discount the high prevalence of HIV and with it the risk of potential numbers of positive tests within the window period that the Rapid Tests may, in fact, miss. Of course, this may negatively impact our business.

From an administrative perspective, Rapid Testing does not require laboratory technicians. This means that these tests may be administered by individuals other than qualified laboratory technician. Since Rapid Tests results are usually delivered by lines formed or colour changes, similar to pregnancy tests, the results may be open to interpretation. From an industry perspective, this certainly reduces the attractiveness of this test, for fear of risk of litigation when false positives arise. Applicants may attribute incorrect results to inappropriately trained personnel reading the test. In addition, in such cases, the appropriate storage and expiry dates of these tests may be challenged.

In addition, since no formal laboratory reports are generated from Rapid HIV Testing, the results of these tests may be vulnerable to fraud. For example, positive HIV results may be being recorded as negative.

Comparing costs of Rapid HIV Tests to ELISA, the Rapid Tests are slightly more expensive than the ELISA. The ELISA incurs the initial investment in equipment and ongoing operational expenses of laboratory technicians and personnel. However, the cost per test of the ELISA may be reduced considerably by batching tests together, making it a more cost-effective option when large numbers of HIV tests are processed at the same time.

Lastly, Rapid Tests should be always be used in conjunction with the clinical status, history, and risk factors of the person being tested. In clinical practice, it usually recommended that these tests be used in settings where there are appropriate multi-test algorithms that include confirmatory tests. The same may be said of formal HIV ELISA tests, which are still regarded as screening tests.

 

What are confirmatory tests?

The most common confirmatory test is the Western Blot. Why does one need to confirm a screening test with sensitivities of close to 100%?

The negative aspect of the high sensitivity of the ELISA (or the Rapid Tests), is that these tests may produce a small number of false-positives. This may occur when there are antibodies to other diseases within the body that the HIV test inadvertently recognises as antibodies to HIV; hence, the test reads as positive. Therefore, a confirmatory test is strongly recommended following a positive ELISA. The most common confirmatory test is the Western blot. This test is less sensitive but more specific, that is, less likely to give false positive results since it can differentiate more accurately the presence of HIV antibodies from other antibodies.

Therefore to summarise, the industry protocol for HIV testing is well-defined, but many may seek quicker and more convenient options. However, HIV is still a highly emotive condition in this country. The risk of litigation, or negative publicity, is great when it involves erroneous HIV results. In addition, there are ethical considerations of a client receiving the incorrect results, the ramifications of which may be considerable. Therefore, it is recommended that insurers follow the formal blood testing route for HIV as per established guidelines.







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