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Anxiety
Unregistered

repeat negative tests
      #43560 - 11/11/02 11:26 AM

The last cdc test of lab performance on elisa test came out to the 99.8% sensitivity, and 99.9% specificity. There were 7 false-negatives out of 3704 tests.

Here are the stats:
http://www.phppo.cdc.gov/mpep/pdf/hiv/0201hiva.pdf

My question is, if there is a 0.2% chance of a false negative, why is it not standard to perform the elisa twice, regardless of whether the 1st is negative? I think most labs only test once if the 1st is negative!!
This would mean that for every 100,000 tests, 200 people will have a false sense of security, and could be out spreading the disease!!

Perfoming the EIA test twice regardless of the status of the first test should be standard to virually eliminate the possibility of any lab errors and false positives. I am now thinking about subjecting myself to the torture of another test because of this. =(



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Anonymoussss
Unregistered

Re: repeat negative tests new
      #43594 - 11/11/02 05:15 PM

Well I read the entire article. What I did notice is that there was no indication of the time span between the "time of possible infection" and the test date. It's possible that these false negatives occurred due to persons testing too soon. Also, the observations were made on a particularly small sample when compared with the larger number of people who are actuallly tested each year. It is important to take these things into consideration when looking at statistics. That's all I can say about that.



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Kevin_In_Sydney
Member

Reged: 10/13/02
Posts: 17
Re: repeat negative tests new
      #43595 - 11/11/02 05:19 PM

Hi Anxiety,

The tests are done twice! Check with the lab before you go testing again.

Regards,

Kevin



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Anxiety
Unregistered

Re: repeat negative tests new
      #43600 - 11/11/02 06:46 PM

ok thanks...I hope you are right!! I dont wanna test again... And I'll never ever ever put myself at risk again!! The 4 days wait cost me my sanity!! Doc had to put me on Anxiety meds during my wait, and 2 months later I'm still taking them. I will check with the lab. thanks..



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Anxiety
Unregistered

Re: repeat negative tests new
      #43602 - 11/11/02 07:06 PM

Although they did not say "how long" they tested, it did say that certain samples were "weakly positve" due to the fact that they were in the process of seroconversion(I wish they would have had how long also). Also, some were "strongly positive", and one was negative. And yes, the weakly positive samples did account for most of the false negatives. It says 3 of the seven false negative were due to donors 4 and 5. (5 was strongly positive, 3 and 4 was weakly positive)

"Testing information for sequential serum samples from Donors 3 and 4 demonstrated factors consistent with seroconversion such as a positive p24 antigen test, positive test for HIV-1 ribonucleic acid (RNA), rising HIV-1 antibody titers in all EIA tests, and WB reactivity changing from nonreactive(no bands) to indeterminate or reactive from one donation to the next.

...Of the seven nonreactive EIA interpretations reported for HIV-1 positive samples, four were reported for Donor 3,
with four different test kits. The remaining three false negative interpretations were reported for Donors 4 and 5 by
laboratories using two different test kits."

Keep in mind, this last 6 months was the best the labs had ever performed. You can view the last 6 years performance at http://www.phppo.cdc.gov/mpep/hiv-1.asp



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uhohblita
Guru

Reged: 05/02/02
Posts: 273
Re: repeat negative tests new
      #43623 - 11/11/02 11:10 PM

how do they know if its a false neg? i dont get it. the sample must have been tested some other way.

or, are they saying that person tested antibody pos. at some other point?

its amazing how some people get p24, rna, wb, etc... my docs never even gave me eia when i had ars symptoms.



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Anonymous
Unregistered

Re: repeat negative tests new
      #43626 - 11/11/02 11:38 PM

Because they are tested by the CDC multiple times by (EIA,PCR,p24) prior to being sent to the labs. They are samples used to determine lab performance in the field



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Anonymous
Unregistered

Re: repeat negative tests new
      #43640 - 11/12/02 12:18 AM

Hey folks, I have researched the site for the last 3 hours. here is my conclusion. Based on all of the samples submitted to the CDC during the last 8 years most false negative results occured during accute infection (WB bands 24, 124 and 160)or something like that. Almost all of these were by 1st Generation EIA's. All of the research I have done states that all 8 WB bands will be present by 5-6 months. Under those circumstances none of these samples was false negative.
CONCLUSION: WB bands 24 and 160 are present between 4-8 weeks in which case 3rd generation will pick it up and 50% of 1st generation will pick up. afetr 3 months propably 4 or more bands will appear on the western blot in which case either 1st or 3rd generation will pick up with the exception of a few odd balls. I guess that's whath the experts have been telling us all along.

I myself have tested multiple times last one over 5 months and don't really know the generation of elisa but according to these results it really would not matter because it would be negative on either one



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uhohblita
Guru

Reged: 05/02/02
Posts: 273
Re: repeat negative tests new
      #43652 - 11/12/02 02:36 AM

thanks for that info.

i guess my point was that the CDC claims 100% on the samples they send in. why then are there people like us who suffer needlessly with knowing LESS than that. we should get the same treatment. less overall dollars would be spent IMHO.



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