Lateral Flow Tests

[237SJ]

What's the chance of 3 negative lateral flow tests being wrong - does anyone know? I saw PP mention something about 5 tests but wasn't really sure what he meant.

[Sqad]

237....I cannot answer your question in the form that you have presented it.

BUT...I am not a fan of the LFT and some studies show that in 50% of negative tests Covid is present in varying degrees of viral load.

[pat2604]

She'd, I don't trust them, but you have to have them if you visit a care home. I would rather not visit, but the lady I visit was my neighbour for over 40 years andhas no other visitors. I take every precaution.

[pat2604]

She'd ? I typed Sqad

[pat2604]

And I got mixed up with the two lateral flow test questions!!!

[237SJ]

Thanks for the replies. I have a bug with some typical covid symptoms and have done 3 LF tests. I`m awaiting the result of a postal PCR so was just wondering if I could pretty much assume I am OK after 3 negative results.

[Sqad]

I think you did it on purpose Lottie, knowing my depth of homophobia-;)

[Sqad]

237.....I think that you should be fine on the LFT'S ,but twill be interesting.

[237SJ]

Thanks sqad. I phoned the doc because I have secondary infection and was surprised she is hoiking me down to the surgery later. I`m a 'hot patient' apparently! Still, at least they are seeing people.

[Sqad]

//////I`m a 'hot patient' apparently////

No surprise there then -;)

[Mamyalynne]

Glad that you're getting seen 237, hope you are soon feeling better.

[237SJ]

Thank you.

[pixie374]

237, we have always fully trusted positive LFTs, but only double- checked negatives.
I only realised today on This Morning, at a client's, that even cold symptoms can give you a false positive LTF. I hadn't known that. But negative, should be right.

[pixie374]

Argh, first sentence the other way round. We only suspect positives.

[Peter Pedant]

of course I know the answer
so long as you are doing it properly ( hence the series of five) it is very slight

https://www.bmj.com/content/372/bmj.n238/rr-0

makes a bit of a meal of all this BUT fiona godlee ( editor of the BMJ silly!) has NO idea about false positive rates - so cdnt curate this letter properly

// the false negative rate would still be relatively low: 0.85% (9 missed cases in every 1000 tests).//

that is for one test - !% are wrong - for three tests if would be 1% of 1% of 1% = piffle
You are negative

ACTUALLY since you have walk ins who rate this site so whether or not TTT exclaims " WULI WULI!" I have to get it right
you should be looking at NPV

negative predictive value ( ot the test) that is - if ithe test is negative what is the chance you DON'T have the disease and that is around 100%
that is if you TEST negative you ARE negative (*)
run of three - even closer to 100%

so that is the answer - you are neg do you have covid nope

(*) testing101 has to get over the fact that
false negarive rate - - is NOT the negative predictive value
which you know med st make a helluva mess of

[237SJ]

Thank you PP and Pixie.

[Sqad]

PP's post is a bit intelligent for me, but this is more my style.

https://www.bmj.com/company/newsroom/uk-government-must-urgently-rethink-lateral-flow-test-roll-out-warn-experts/

[237SJ]

But then, this morning I read this https://www.bbc.co.uk/news/health-58899612

[pixie374]

At the moment, one negative LFT is enough for hospitals and care homes. Only the positive ones haven't been trusted. If that helps...

[pixie374]

Sqad, is that about all of them, or one particular brand?

[Netty7]

LFTs are ok if done at the right time. They are accurate I think if you’re doing them to make sure you’re not carrying any infection if you are intending to visit someone or go to an event, but have no symptoms. I think that once you have any symptoms at all they don’t then pick it up so shows negative. I’ve had friends that are in jobs which require LFTs all the time. One had a cough and tested negative every time on LFT but had a PCR which was positive. So to me if there are no symptoms LFTs are accurate but once there’s the slightest symptom only a PCR will pick it up.