Author Topic: Reading Viral Loads (Read 18697 times)

lporterrn · « **on:** March 23, 2015, 02:15:53 pm »

Hi Everyone,
I am going to post this in 2 places, but I am posting it here first because I was inspired to write this because viral load questions come up a lot here: http://blogs.hepmag.com/lucindakporter/2015/03/new_hepatitis_c_trea_2.html
Hope it is helpful.

dragonslayer · « **Reply #1 on:** March 23, 2015, 02:36:25 pm »

Lucinda,

Thanks for posting this, and referring to the 'Clinical Infectious Diseases, March 2, 2015' study reference.

I wanted to question you on one statement in your enlightening blog enry:

"For instance, the Abbott RealTime HCV assay (assay is a fancy word for a test that determines and measure the ingredients of something) measures down to 12 IU/mL in a 0.5 mL sample of blood. This means that if you have 12 IU/ml of hepatitis C (HCV RNA) in your blood, the test will detect it. If you have less than 12, the test won't see it."

What is not addressed here is the most confusing result of all, ie, when the Abbott RT assay comes back with a Detected < LLOQ(12). Here, its detected, but the count too low to be quantified... The test 'sees' it but cant measure it.. More confusing is that in this test, both the LOD and the LLOQ is 12... Superficially, youd think that if its below 12, then it cant be detected OR quantified, which , apparently, is not the case.. It's still being detected, even below the LOD! Paradox? There is an arcane explanation for this, but its really above my pay grade... Lastly, as you so well indicated, what's Undetected in one assay, can be low level detected in another.

But the key point you drove home is that low detected results at end of treatment are NOT predictors of failure! That, being a huge departure from earlier treatments, really changes the landscape.

Thanks again for your blog entry!

Bituman · « **Reply #2 on:** March 23, 2015, 07:17:39 pm »

Thanks Lucinda, that's a great summary. That should put a lot of folks at ease.

Bob

koifish54 · « **Reply #3 on:** March 23, 2015, 09:57:29 pm »

Thanks Lucinda

atomic dog · « **Reply #4 on:** March 23, 2015, 10:38:23 pm »

Quote from: lporterrn on March 23, 2015, 02:15:53 pm

Hi Everyone,
I am going to post this in 2 places, but I am posting it here first because I was inspired to write this because viral load questions come up a lot here: http://blogs.hepmag.com/lucindakporter/2015/03/new_hepatitis_c_trea_2.html
Hope it is helpful.

Thanks so much for posting this (I'm one of those still detected at Week 3 folks). I was disturbed to read on the forum yesterday that someone wrote Hep C can "hide" in the teeth. Personally, I have no plans to have all my teeth yanked as a preemptive measure. The truth shall set you free . . . and the science.

lporterrn · « **Reply #5 on:** March 24, 2015, 12:07:35 am »

Hi Paul,
Than you for pointing that out - I had intended to say that, but got sidetracked by trying to make another point. (I was trying not to bring in LLOQ and LOD to keep it simple) So, your feedback helped remind me of my intention, and I rewrote is like this:

Quote

This means that if you have 12 IU/ml of hepatitis C (HCV RNA) in your blood, the test will detect it and count it. If you have less than 12, the test might not see it, and if it does, it won't be able to count it.

chino1969 · « **Reply #6 on:** March 25, 2015, 12:43:32 pm »

Thank you Lucinda.

C-FIGHTER · « **Reply #7 on:** March 25, 2015, 06:19:38 pm »

Lucinda,

great article, great information. thank you so much.

cherokee52 · « **Reply #8 on:** March 25, 2015, 06:36:32 pm »

HCV RNA, QUANTITATIVE REAL TIME PCR <15 NOT DETECTED
<15 (IU/mL)

HCV RNA, QUANTITATIVE REAL TIME PCR <1.18 NOT DETECTED
<1.18 (Log IU/mL)

Hi my name is Paul and not being very versed in reading these results can you tell me what this means. I have been on Harvoni for 5 weeks and this is what my first viral load reads.
Thank you ,... Paul

chino1969 · « **Reply #9 on:** March 25, 2015, 06:51:50 pm »

cherokee52,
That's good news. It means the virus is no longer detectable in your blood. Congratulations.

cherokee52 · « **Reply #10 on:** March 25, 2015, 10:24:35 pm »

Wow after just 5 weeks ?... that stuff is good(expensive but good) thank you for your reply.

lporterrn · « **Reply #11 on:** March 26, 2015, 12:07:55 am »

Great news cherokee!!

Lynn K · « **Reply #12 on:** March 26, 2015, 02:39:59 am »

Yes amazing stuff indeed cherokee. Some have tested undetected as soon as 2 weeks on tx wow!

I was UND at 4 weeks was not tested before that. I am not sure why some are testing that early but still a great data point for all to see!

Long_Haul · « **Reply #13 on:** March 26, 2015, 10:02:21 am »

Congratulations Cherokee, Glad to hear you are UNDETECTED. I know it was so reassuring to get that report. Keep taking you meds and you will make SVR12.

Best wishes,

AL

chino1969 · « **Reply #14 on:** March 27, 2015, 07:42:15 pm »

Am I understanding this correctly? The Abbott test if < 12 iU/mL the virus is considered non detectable. The COBAS TaqMan test if <15 iU/mL the virus is considered non detectable. Is it just that one test is more sensitive than the other? Is one test preferred over the other in order to make a definite call that the virus has been eradicated?

BubbaT · « **Reply #15 on:** March 27, 2015, 08:18:31 pm »

Thank you Lucinda,

What a great friend you are to us, blessing to u!

Lynn K · « **Reply #16 on:** March 27, 2015, 10:20:14 pm »

Hi Chino

Yes the two different lab test from two different laboratories to have a different LLOQ of 3 IU/mL however at least on my lab test there are 2 options <15 IU/mL detected or virus not detected

Copied from my test report

HCV RNA RT-PCR, QT See Notes IU/mL result HCV Not Detected

The quantitative range of the assay is 15 IU/mL to 100 million IU/mL
using COBAS(R) TaqMan(R) HCV test, v 2.0. The limit of detection (LOD)
and lower limit of quantification (LLOQ) for this assay is 15 IU/mL.
Results less than the quantitative range of the assay will be reported
as "HCV RNA detected, less than 15 IU/mL".

So not knowing the specifics of your labs reporting practices with my lab they do specifically say either: not detected, or less than 15 IU/mL detected.

No on treatment test determines viral eradication only post treatment testing when tested 12 or 24 weeks post EOT and the virus has not returned will definitively show if the virus has been eradicated.

I tested not detected after 4 weeks on treatment and at EOT after treating for 12 weeks with Sovaldi & Olysio last year.

When tested 12 weeks later I was found to have relapsed and my viral load had returned to pretreatment levels of HCV RNA RT-PCR, QT result 2,422,260 IU/mL; HCV LOG 10 result 6.384 log10 IU/mL in those 12 weeks. So not just a few but millions of virus.

Hope that helps

MEG · « **Reply #17 on:** March 27, 2015, 11:09:44 pm »

Thanks so much, Lucinda. I can't read about these nuances in viral load reports enough.

dragonslayer · « **Reply #18 on:** March 27, 2015, 11:26:35 pm »

>> The limit of detection (LOD)
and lower limit of quantification (LLOQ) for this assay is 15 IU/mL.
Results less than the quantitative range of the assay will be reported
as "HCV RNA detected, less than 15 IU/mL<<

Except, of course, when its reported as Undetectable. This is still a logical problem for me, though.. Simply, if the LLOQ and the LOD values are the same, which for both this test and the Abbott assay they are, then if the result is lower than the LLOQ, then its also lower then the LOD.... Therefore, using the mathematical property of equality, if its too low to be quantified, then it should be too low to be detected. Therefore, a result < LLOQ but Detected should be impossible. Mike has put up articles which attempt to explain this, but its still a mystery.

One more question: I see that the LLOQ value for the Cobas TaqMan v2 assay is 15, and for the Abbbott rt assay its 12. In the Gilead prescribing doc, you can find the following excerpt:

" Serum HCV RNA values were measured during the clinical trials using the COBAS TaqMan HCV test (version 2.0), for use with the High Pure System. The assay had a lower limit of quantification (LLOQ) of 25 IU/mL."

And it was this LLoQ value of 25 that they used to determine SVR for their results, which must mean they are using some results that were <LLoQ(25) but detectable at 12 wks post treatment in their SVR ratios. So according to this, its possible to test < LLoQ but Detectable at 12 wks post treatment and still be SVR. It stands to reason that this is more representative of a testing failure than a failure in treatment since its highly unlikely that you can still be detected at 12 wks post treatment but have a lower than LLoQ value and still have active virus... Ive never heard of anybody relapsing with a viral load < LLoQ!

It certainly is a new day not just in the meds being offered, but in how we evaluate success!

Lynn K · « **Reply #19 on:** March 28, 2015, 02:05:27 am »

Hey I'm just a simple caveman lawyer lol there is only one viral load that I care about 12 week and 24 weeks post treatment test result either it will be not detected or back in the millions that is the one for all the marbles the others really don't matter unless you are a researcher

chino1969 · « **Reply #20 on:** March 28, 2015, 07:58:52 am »

Hi Lynn K,
Thanx for the response. Our situation is very similar. I went through 12 weeks of Solvadi/Olysio last year. My viral load last year @ 2 & 12 weeks was not detected, however, 2 months later it was back to 4,927,490 IU/mL & 6.693 log10 IU/mL.

I'm now on a 24 week regimen of Harvoni. My 4 week viral load (HCV RT-PCR , Quant [Non-Graph]) is not detected. I am happy but cautiously optimistic based on my previous results.

In addition to seeing my regular gastro. I am now seeing a renowned hepatologist at a well known teaching hospital. My 1st consult was with him in Feb. 2015. He told me that had I been on a 24 week course of Solvadi/Olysio, there was a very good chance it would have succeeded into eradicating the virus. He was involved in the clinical trials of Harvoni and has written many articles on Hep C.

Let's hope and pray that this time around we both beat this insidious disease.

Lynn K · « **Reply #21 on:** March 28, 2015, 09:38:22 pm »

Right there with you chino!

Yeah I treated March to June and in Nov they changed the recommendation to 24 for folks like us. I was not detected at week 4 and 12 Harvoni 5 weeks to go on 24 weeks of Harvoni with Riba added later at week 9 so 15 weeks of Riba when all is done.

My doctor is the head of the lver center at a transplant hospital in Seattle and is also a transplant doctor. I guess Kris Kowdely is on the staff there he is a writer of many of the reports we read.

Good luck hope we both made SVR

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Author Topic: Reading Viral Loads (Read 18697 times)