The Performance Rate for the Combined ELISA and WESTERN BLOT HIV Test - Is 99% Accuracy Good Enough? The Answer: NO!

Author

  • The Perth Group

  • Eleni Papadopulos

  • Valendar Turner

  • John M. Papadimitriou

  • Harvey Bialy

Publisher

  • AIDS Update

Category

  • HIV Tests

Topic

  • HIV Test Accuracy

Article Type

  • Column

Publish Year

  • 1999

Meta Description

  • The content discusses the accuracy of ELISA and Western Blot HIV tests. Despite a 99% accuracy rate, the risk of false positives and negatives remains.

Summary

  • The content discusses the accuracy of the ELISA and Western blot HIV tests, which are used to identify HIV. The Centers for Disease Control and Prevention (CDC) claims that these tests have a 99% accuracy rate when performed repeatedly. However, the exact rate is unknown, and the CDC has no data on false positives or false negatives. The risk of testing falsely positive with a 99% accuracy rate is 0.3%, which may seem low but can have significant consequences for individuals. False-positive results can harm personal and professional lives, and there is a danger that false-positive individuals may not take precautions to avoid infecting others. The occurrence of even a small number of false-positive HIV tests can have profound implications, especially when testing blood donors. These false-positive results waste resources and require more expensive tests for verification.

Meta Tag

  • HIV Test

  • ELISA

  • Western Blot

  • Accuracy

  • False Positives

  • False Negatives

  • CDC (Centers for Disease Control and Prevention)

  • Performance Rate

  • 99% Accuracy

  • AIDS

  • Test Results

  • Infection

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  • Keyword of the image

By Gerald J. Stine Ph.D.*
University of North Florida, Jacksonville.
AIDS Update 1999


Even when the AIDS orthodoxy admits the cold figures and hard facts their interpretation is delusional. What follows is a perfect example:
- AIDS UPDATE 1999 -

THE PERFORMANCE RATE FOR THE COMBINED ELISA AND WESTERN BLOT HIV TEST - IS 99% ACCURACY GOOD ENOUGH? THE ANSWER: NO!

The Centers for Disease Control and Prevention (CDC) states that the two tests used to identify HIV - the ELISA and the Western blot (WB) - used in combination, have a better than 99% accuracy rate, but only if they are performed repeatedly. (The exact rate is unknown and the CDC states that it has no data on just how many false positives versus false negatives occur!)[1] The rate is the percentage of correct test results in all specimens tested. With a 99% rate, if a population of 10,000 were tested, 9,900 would receive correct results, but 100 would receive erroneous results - either false positives or false negatives - including indeterminates.

If 99% accuracy is used as an example, the false positives would have to be less than 6/10ths (0.6%) of the erroneous results, because the CDC estimates that 0.6% of Americans are HIV-positive. That is, if false positives account for fully 0.6% of the errors, then the 0.6% of people who are HIV-positive would all be false positives, and that is not the case. However, if one assumes that only 0.2% are false positives, this leaves 0.8% as false negatives. So, of those same 100 people with erroneous results, 20% would be false positives and 80% would be false negatives. False negative people are an unwitting threat to sex partners. But there is still another ramification: using the CDC estimate that 0.6% of Americans are HIV-positive, in a population of 10,000, 60 Americans would test positive! This 60 must include all the false positives, 30, leaving only 30 people actually infected. This leads to the following conclusion: using a 99% accuracy, one finds as many false positives as true positives.

Even if the results of both AIDS tests, the ELISA and WB, are positive, the chances are only 50-50 that the individual is infected. This is why people with HIV-positive results must be tested repeatedly over the following 6 months to 1 year. The error rate of 99% accuracy is high with only two tests. (The CDC's Morbidity and Mortality Weekly Report shows an overall performance rate of only 98.4% on the Western Blot alone - a lower accuracy than that used in this example). Even with repeated HIV-positive tests, the rare person may just be a false-positive tester.[2]

The implications of a false positive test are broad for people tested at random. For example, a person was recently HIV-tested for a routine insurance examination. Because he or she had no behavioral risk factors and was in excellent health there was no concern about testing HIV-positive. The major concern is testing falsely positive - that risk, with a 99% accuracy testing procedure, is 30 out of 10,000 (0.3%). This may appear to be a low risk, but it isn't if you are one of the 30 - after all, 30 people out of 10,000 will be false positive. The results can destroy one's personal and professional life; other people believe your test results even if they are later found to be in error. It's like the newspaper scenario: retractions are found in small print on the back page - somewhere.

There is also the danger that false-positive people will not feel the need to avoid sex with truly infected people - a good route to infection.[3]

But there is also room for optimism in these statistics. An individual who is a random false positive can find hope in them. This does not mean that he or she can take chances with other people's lives, so each person must behave as though he or she is actually infected. But, inwardly, the random false HIV-positive individual can be cautiously optimistic.[4]

The occurrence of even a small number of false-positive HIV tests can have profound implications. This is especially true when testing blood donors, since false-positive results waste resources in discarded blood units and require verification of positive results using more expensive tests. A false negative result, indicating that an individual is not infected, can have serious consequences for the blood recipient. Therefore, attempts to improve tests are a continuous challenge.[5]

From: AIDS Update 1999 by Gerald J. Stine Ph.D.*
University of North Florida, Jacksonville.

Commentary:

  1. This is because they have NEVER ISOLATED "HIV" FROM FRESH PATIENT PLASMA.

  2. Obviously, repeating the tests will only clear up false positives due to things like goofs in the lab. Any of 60+ conditions could persistently turn the test false positive.

  3. Here things turn really twisty. It may be a good argument to offer the safe sex/condom missionaries as to why HIV testing is a bad idea. But seriously now, how do the false-positive people know they aren't true-positive people, or visa versa? The author has just told us even the CDC won't hazard a guess.

  4. That sermon was too much! Could you hear the gospel tune on the little Hammond organ? The "random false HIV-positive individual" - what is that? A victim of a drive-by shooting?

  5. "It's a sad night when a pint of good blood goes to waste," said the Vampire. We've got to keep the blood supply clean, as we know what sort of liabilitie$ are involved. So what if a few false-positive people get wasted? Only homosexuals, IV drug users, pregnant women, hemophiliacs, and blood donors are at risk of HIV testing anyway.

And this was printed in a college level textbook!

  • Gerald J. Stine Ph.D. is the author of eight other HIV/AIDS college-level textbooks "dedicated to those who have died of AIDS, those who have HIV disease, and to those who must prevent the spread of this plague - EVERYONE, EVERYWHERE."