HIV test - positive then negative?

Automated Response

I just had a HIV test done. The first result was positive and the second test (some kind of re-test?) came back negative. So obviously one of the results is wrong. I got more blood taken today to be sent off for special analysis. Apparently this test is pretty much the definitive one.

Anyone have experience with a situation like this? I am pretty worried about the whole thing...

Bottle_of_Smoke

According to Dr.House hepatitis vaccinations can lead to an increased liklihood of a false positive for HIV.

I'd imagine other things too. Was it the instant test? The one which takes longer looks for anti-bodies, may be more conclusive.

Best of look either way mate.

LegacyUser

It could go either way of course, but false positives are way more common than false negatives

seamus

Positive HIV results can be incorrect 50% of the time if you're a straight man who generally uses protection.

Detection for HIV seems to be under a bit of argument when basic tests are used as it seems to gather a lot more false positives than it should. The statistics are on your side here - both the positive and negative results are only indicators, but the fact that the second test came back negative indicates that an overall negative is the most likely outcome of the more rigourous test.

In any case, do your best not to dwell on this too much until the results come back. Even if you do end up being HIV positive, the condition is far more manageable than it's ever been and it's not the same grim diagnosis that it used to be or that you'd get with cancer.

Best of luck.

Automated Response

Thanks guys, you've managed to put my mind at least partly at ease! It came out of nowhere. When I took the test I hadn't even entertained the possibility of being positive. Deep down I don't think that I am but it's going to be a tense week until I can get the results back.. Anyway, thanks again!

Kevo

Have a look at this. It's an interesting bit of statistics which applies to your situation.

Anyway, I hope that puts your mind at ease and as has been said, HIV is far more manageable than it used to be. Best of luck.

Emme

If you still have doubts go back to your STI clinic and get checked again or discuss the results with them. I wouldn't leave that sort of thing to anybody but a qualified professional.

Johnny Favourite

you should watch a documentary called " House of Numbers" its all about HIV testing. Very interesting.

I can't find a link but if you google it I'm sure you will find it.

Good Luck.

seamus

Just to give a quick breakdown of why we're talking about statistics when the OP asked about HIV (my figures are a few years old, things might be more accurate now):

The incidence of HIV in straight men who are generally careful is about 1 in 10,000. By coincidence, the error rate for the standard HIV test is about 1 false positive in 10,000. That is, for every 10,000 tests, you will get one positive result which is incorrect.

What this means is that for every 10,000 such men tested, you will get two positive results - 1 correct and 1 incorrect.

If you take all of the positive results are a single group, then you can see that half of all positive results are incorrect. That is, if 60,000 men are tested this year, there will be 12 positive results, 6 of which are incorrect.

Therefore if you get a positive HIV result on a test, there is a 50% chance that it is incorrect.

If they do a second test and it comes back negative, the odds are overwhelmingly stacked in your favour that the first test was incorrect because the odds of the second test being incorrect are very low (0.0003% or something like that).

As I say, my figures might be off at this stage, and the OP may not be in that single group I mention above.

IITYWYBMAD

seamus wrote: »

Just to give a quick breakdown of why we're talking about statistics when the OP asked about HIV (my figures are a few years old, things might be more accurate now):

The incidence of HIV in straight men who are generally careful is about 1 in 10,000. By coincidence, the error rate for the standard HIV test is about 1 false positive in 10,000. That is, for every 10,000 tests, you will get one positive result which is incorrect.

What this means is that for every 10,000 such men tested, you will get two positive results - 1 correct and 1 incorrect.

If you take all of the positive results are a single group, then you can see that half of all positive results are incorrect. That is, if 60,000 men are tested this year, there will be 12 positive results, 6 of which are incorrect.

Therefore if you get a positive HIV result on a test, there is a 50% chance that it is incorrect.

If they do a second test and it comes back negative, the odds are overwhelmingly stacked in your favour that the first test was incorrect because the odds of the second test being incorrect are very low (0.0003% or something like that).

As I say, my figures might be off at this stage, and the OP may not be in that single group I mention above.

According to wiki :

The specificity rate given here for the inexpensive enzyme immunoassay screening tests indicates that, in 1,000 positive HIV test results, about 15 of these results will be a false positive. Confirming the test result (i.e., by repeating the test, if this option is available) could reduce the ultimate likelihood of a false positive to about 1 result in 250,000 tests given.

magneticimpulse

Your statistics are sort of meaningless. You have to factor in the country and general sexual health of a country and the liklihood of contracting HIV.

When I had an STD test in the UK, they asked if any of my previous sexual partners were African, as they said they are consider a high risk catergory.

I assume the population of Ireland was some what low risk at contracting HIV, but these days the risk is far higher with more immigration from different countries, who have different attitudes to getting STD tests and basically no care for sexual health. Combine that with the increase % of young people having unprotected sex with lots of casual partners and assuming AIDS is just an African or Drug User problem.

So any statistics are going to have loads of variables.

dudara

Posters - this is not a place for discussing testing statistics. I think that you've given a lot of answers which should help the OP, but let's not obscure the topic.

dudara

Bottle_of_Smoke

IITYWYBMAD wrote: »

According to wiki :

The specificity rate given here for the inexpensive enzyme immunoassay screening tests indicates that, in 1,000 positive HIV test results, about 15 of these results will be a false positive. Confirming the test result (i.e., by repeating the test, if this option is available) could reduce the ultimate likelihood of a false positive to about 1 result in 250,000 tests given.

The poster got a positive result then a negative not two positive results.

Dudara I genuinely don't mean this as a statistics argument just pointing out an error that has the potential to scare the OP

Uriel.

To be honest, nobody can give the OP any form of accurate advice based on the information that he/she has provided.

A number of factors are at play.

What kind of test was it - Oral or blood. ELISA Antibody or Particle Test
What is the OPs Sexual History - homo or heterosexual male?
What is the OPs sex?
Is the OP on any medication?
Has the OP recently received an Vaccinations?
Has the OP any form of immune deficiency illness etc...
Why was the OP testing for HIV?
Is a specific encounter a worry for the OP?
If so, what is the time differentiation between the encounter and the test.

All of the above (and more) can have a significant baring on the accuracy of a HIV test (negative or positive).

OP I imagine the test that is being carried out on your blood now (the more "definitive" test) is the Western Blot Test. A positive diagnosis on an ELISA or Particle test is not confirmed until the Western Blot test is performed. If you're initial test was a particle test, the rate of false positives is considerably higher than that of a standard ELISA. This is one of the primary reasons (along with cost) that particle tests are not approved as a regular diagnostic test.

OP, to be honest, you need to look at your sexual history to determine how worried you should be by the positive result, and not solely at the result.

Best of luck with the Western Blot.

If it does turn out to be positive, please take solace in the fact that HIV diagnosis is not the death sentence it once was. It is a chronic illness for sure, but thanks to advancements in knowledge and treatment, it is a very treatable and managable disease (such as diabetes). The vast vast vast majority of people can live an almost normal life like everyone else.

Though we are a considerable way from a cure for the illness, we do make inroads and advancements in treatments on an on-going basis. Things wil only get better with HIV management.

best of luck.

IITYWYBMAD

Bottle_of_Smoke wrote: »

The poster got a positive result then a negative not two positive results.

Dudara I genuinely don't mean this as a statistics argument just pointing out an error that has the potential to scare the OP

If you noticed, I quoted Seamus's post where he claimed that the chance of getting a FP were 1 in 10,000. He also said that the chance of getting a further FP are .0003%.

Wiki seems to suggest that the chances are higher of getting a FP, and therfore the OP should not be as concerned as he/she may be. That's what I was saying.

Anyhow, as has been said, this is probably not the area to discuss stats, and there is plenty of info available elsewhere.

Uriel.

IITYWYBMAD wrote: »

If you noticed, I quoted Seamus's post where he claimed that the chance of getting a FP were 1 in 10,000. He also said that the chance of getting a further FP are .0003%.

Wiki seems to suggest that the chances are higher of getting a FP, and therfore the OP should not be as concerned as he/she may be. That's what I was saying.

Anyhow, as has been said, this is probably not the area to discuss stats, and there is plenty of info available elsewhere.

To be honest, you can throw as many stats at the OP as you like, they will have no relevance on the basis of the information provided thus far.

Uriel.

fasdfsadfwe wrote: »

It could go either way of course, but false positives are way more common than false negatives

Very misleading statement to make.

Proportionally false negatives generally might not happen so often. This is due to the fact that the vast majority of people testing will ultimately test genuinely negative and not have to worry about HIV.

But realistically the potential of a false negative is far higher than a false positive, due to incorrect testing time and other factors.

In this case, you can't just say it will go "either way". It completely depends on a huge number of factors/variables realting to the OP (which have not been outlined in this thread).

Bottle_of_Smoke

IITYWYBMAD wrote: »

If you noticed, I quoted Seamus's post where he claimed that the chance of getting a FP were 1 in 10,000. He also said that the chance of getting a further FP are .0003%.

Wiki seems to suggest that the chances are higher of getting a FP, and therfore the OP should not be as concerned as he/she may be. That's what I was saying.

Anyhow, as has been said, this is probably not the area to discuss stats, and there is plenty of info available elsewhere.

Ah fair enough. When you said Confirming the test result (i.e., by repeating the test, if this option is available) could reduce the ultimate likelihood of a false positive to about 1 result in 250,000 tests given I thought you meant a second positive result and chances of that being wrong was 1/250000

Automated Response

Uriel. wrote: »

To be honest, nobody can give the OP any form of accurate advice based on the information that he/she has provided.

A number of factors are at play.

What kind of test was it - Oral or blood. ELISA Antibody or Particle Test
What is the OPs Sexual History - homo or heterosexual male?
What is the OPs sex?
Is the OP on any medication?
Has the OP recently received an Vaccinations?
Has the OP any form of immune deficiency illness etc...
Why was the OP testing for HIV?
Is a specific encounter a worry for the OP?
If so, what is the time differentiation between the encounter and the test.

All of the above (and more) can have a significant baring on the accuracy of a HIV test (negative or positive).

OP I imagine the test that is being carried out on your blood now (the more "definitive" test) is the Western Blot Test. A positive diagnosis on an ELISA or Particle test is not confirmed until the Western Blot test is performed. If you're initial test was a particle test, the rate of false positives is considerably higher than that of a standard ELISA. This is one of the primary reasons (along with cost) that particle tests are not approved as a regular diagnostic test.

OP, to be honest, you need to look at your sexual history to determine how worried you should be by the positive result, and not solely at the result.

.

Thank you for the informed reply. In answer to your questions;

It was a blood test carried out in a foreign country but I don't know which type of blood test exactly.
I am a heterosexual male and I wouldn't say that I have had that many previous partners, especially in the last 8-10 months.
I am not on medication.
I haven't received any vaccinations lately.
I am not aware of any immune deficiency illness.
The HIV test was mandatory - it wasn't because I thought I may have needed it.
There was no real specific encounter that worried me prior to the results but now I am beginning to wonder.. It makes you second guess and worry about everything!

Sorry if I was a bit vague initially.

The test itself was quite inexpensive. It was done in a pretty small clinic/hospital. 2 or 3 days after it I was told that the first result returned positive and the second result ('more detailed' was mentioned I think but I can't be sure now, my head is all over the place) was negative. So 1 of these has to be incorrect. Which is more likely to be incorrect? Should I take it as a good sign that the second result was negative or can a false negative follow a positive? The doctor said this was the screening test?

You're right about the next test, it's a western blot test and is supposed to be pretty much definitive. It was done at a much larger hospital and was pretty expensive.

Uriel.

Automated Response wrote: »

Thank you for the informed reply. In answer to your questions;

It was a blood test carried out in a foreign country but I don't know which type of blood test exactly.
I am a heterosexual male and I wouldn't say that I have had that many previous partners, especially in the last 8-10 months.
I am not on medication.
I haven't received any vaccinations lately.
I am not aware of any immune deficiency illness.
The HIV test was mandatory - it wasn't because I thought I may have needed it.
There was no real specific encounter that worried me prior to the results but now I am beginning to wonder.. It makes you second guess and worry about everything!

Sorry if I was a bit vague initially.

The test itself was quite inexpensive. It was done in a pretty small clinic/hospital. 2 or 3 days after it I was told that the first result returned positive and the second result ('more detailed' was mentioned I think but I can't be sure now, my head is all over the place) was negative. So 1 of these has to be incorrect. Which is more likely to be incorrect? Should I take it as a good sign that the second result was negative or can a false negative follow a positive? The doctor said this was the screening test?

You're right about the next test, it's a western blot test and is supposed to be pretty much definitive. It was done at a much larger hospital and was pretty expensive.

Hi AutomatedResponse,

Thanks for coming back with the more detailed answers. I hope I can help you a little further.

I suppose off the bat, I should say that a little bit of the below will be slight guess work (based on informed assumptions). Unfortunately, there are a few gaps in information to work with but hopefully I can help.

Acute HIV infection:
in the first (approx) 7 to 14 days of initial HIV infection, the presence of the HIV in the blood can be detected via particle tests (PCR RNA). As previously mentioned this is not an approved diagnostic test but it is common for allaying psychological fears in the first few weeks of a potential exposure. The primary purpose of this test is to monitor the level of HIV in the body during long-term health management and medication regimes. The test can produce false positives for a variety of reasons.

After about 14 days the body starts to produce antibodies to try fight the virus. Usually at this stage antobodies are not detectable by tests. Modern HIV testing can begin to detect these antibodies from around 6 weeks (everybody is different in terms of the amount of and the timing of producing antibodies). However, the definitive appproved window period is 12 weeks.

In your case, as you don't know what testing was done it's difficult to give a completely accurate brief of your own situation. I assume you were going for either a job or a visa. Most companies would undertake a standard ELISA antibody test. The reason I say this is thus - a person with HIV and on a medication regime may have undetecable HIV particles in their system due to the current success of the medication they are taking (also because ELISA Tests are FDA/EDA/WHO approved and cheaper).

In your case, you tested positive (assuming this is the test they performed) for the antibody (while it doesn't happen falsely on very regular basis - it does happen and for a variety of reasons). The second test then was the PCR test. A negative PCR test would indicate that the Antibody test was a false positive. HOWEVER, really the after having an initial positive test, the Western Blot test should have been ordered before doing a PCR (of course maybe they just did another ELISA test - but I would not see the point).

Based on the Assumptions that you got 1. ELISA Test. 2. PCR. 3. W.Blot (awaiting results). Then you almost certainly do not have HIV.

Your sexual history would put you in a low risk category also.

To be honest I wouldn't worry too much about this. It really sucks when a false positive springs up but it happens. Your second test was negative and I would be willing to wager that the WB test will give you final certain confirmation.

If you have any others questions or if the above is difficult to understand (it's a complicated subject). feel free to ask more questions.
Best of luck

Automated Response

Got the all-clear yesterday thank god!

Just wanted to thank everyone for the help and the advice. It was much appreciated!!

franklyon

very happy for you AR, God knows what must have been going through your mind.:(

Uriel.

Automated Response wrote: »

Got the all-clear yesterday thank god!

Just wanted to thank everyone for the help and the advice. It was much appreciated!!

Great News.

Such a pity that you had to go through the agony of a false Positive but at least the final result is the best possible outcome.

Thanks for coming back and sharing the good news.

shocksy

just came across your post OP.

Great news that you got the all clear

zero_nine

Kevo wrote: »

Have a look at this. It's an interesting bit of statistics which applies to your situation.

Anyway, I hope that puts your mind at ease and as has been said, HIV is far more manageable than it used to be. Best of luck.

Very interesting, thanks for posting

wealthyman

Hi this thread is not too old so I think it is ok to revive.

I am having an HIV test in the morning with my GP via a blood test due to having unprotected oral sex with another man four months ago. However I have Cystic Fibrosis and am worried about getting a false positive. I had a flu vaccine 3 months ago and these factors could add to this. Is this very common?