What is "Undetectable" and "SVR"

I saw a posting from 2005 which discussed the various possibilities of the term "Undetectable".  In my study lab values that are very low are still indicated as discernable such as <43 or <25.  When the lab determines that the virus is truly "undetectable", they use the word "undetectable".  To my mind, saying different is confusing for people.  However, there may be something I am not aware of here.  Do some labs simply stop after they get to <43 or <25 and do not use the term "undetectable" on the results?  Also, what constitutes SVR?  Is it an undetectable level of virus in the blood 6 months after dosing?  6 months after the "undetectable" level is reached?  Or is it however long the study period says it is e.g. if the study has a year follow up from the date of the last dose, then the determination that the person is SVR is made a year after that last dose.  Interested in the opinion of others here.

[lynda607]

LabCorp offers:

The NGI QuantaSure assay  which has a quantitative range of 2-2,000,000 IU/mL or 5-5,000,000 copies/mL.  The level of detection goes down to 2 IU/mL which is very sensitive.  Anything above 2 IU/mL will be reported as HCV RNA detected and numeric number will be assigned.

HCV RT-PCR Quantitative

The limit of detection of this assay is 7.1 IU/mL and the quantitative range of the assay is 43 to 69,0000.  The test cannot pick up anything below 7.1 IU/mL and the results will be reported below 43 IU/mL HCV RNA not detected. If HCV RNA is detected between 7.1 and 42 IU/mL it will be reported as below 43 IU/mL HCV RNA detected but a numeric number will not be assigned.  If 43 IU/mL or above it will be reported and HCV RNA detected and numeric number will be assigned.

The trial PCRs that use the under 25 IU/mL have a level of detection down to 10 IU/mL ( I think)  It can't detected HCV RNA below 10 IU/ml so if no HCV RNA detected it will be reported not detected.  The assay can't assign a numeric number for any HCV RNA detected between 10 IU/ml and 24 IU/mL so if HCV RNA is detected between 10 IU/mL and 24 IU/mL it will be reported as detected but below 25 IU/mL.  If RNA detected at 25 IU/mL or above it will reported as detected and numeric number will be assigned.

Info on the Quest Heptimax was given above.

[EyesofBlue55]

Undetectable means no virus is found in your blood.SVR(Sustained Viral Response) means no virus is found at the 6 month mark after finishing the drugs.Technically "Cured" !!!

[elpasolady]

From what I know based on what I have learned on this forum ( I know someone will correct me if I am wrong)....the UND depends on which test is being used.  I will give Quest as an example as that is the one that I use.  
The  HCV RNA  Quanitative Real Time PCR is the general  test used to determine someones VL, anytime one discovers that they have HCV and/or before treatment.  That is your baseline and that test sensitivity is <43 to 69.000,000.
There is another test from Quest called the TMA that has a sensitivity  of <5 to 7,5000.  They also have a test called the HEPTIMAX that includes both of the above.  It is more comprehensive.
So, in the first test mentioned, UND would be anything under 43.  In the second test UND is anything under 5.
With the addition of the new drugs, the lower sensitivity is so important when deciding to treat for 24 or 48 weeks, in the case of INCIVEK.  I understand, both drugs want you to have a VL of under 10 to be considered UND.
I just went for my 4 week blood test yesterday. My Dr wanted the Heptimax as my first test.  If I come back UND or at least under 1000
(the futility number that requires treatment discontinutation) then the  nex test will just be the TMA.
SVR means that after treatment has ended, whatever that length is for YOU, then you still need to be UND 6 months later, to be considered SVR.
If I am wrong about any of this. please let me know, for those who will read this.
Good luck and best wishes~Debbie

[nygirl7]

Undetectible just means that the virus is not discernable in your blood but it can still be there or elsewhere in your body.

This is why we do treatment after we are UND - hoping to kill off the virus that might still be around. This is why people who are UND can also later relapse after the meds are removed.

SVR is systemic viralological reesponse which means that six months after the meds are stopped the virus is either gone or suppressed to such low levels that it cannot replicate. That is the beauty of interferon, even though it totally *****, we have natural interferon in our bodies and the treatment process teaches our bodies how to ramp it up so that it can do this job.

Breakthrough is when the virus comes back during treatment, relapse is when it comes back after the meds are discontinued.

[nygirl7]

supposed to say virological but I'm a bad typist.

[curiouslady1]

On the undetectable definition:  Why is it that my lab will give values such as <43 and then <25 and then "undetectable" if <43 is considered "undetectable"?  Clearly, this lab (and I don't know what lab it is as this is an experimental study) does not view <25 as undetectable.  The implication is that the word "undetectable" must be used by the lab (at least it is so in our study) and < is not considered undetectable status.

If, hypothetically, the meds were stopped at Time A with some detectable virus and later, at Time B the virus became undetectable perhaps due to good immune functioning or whatever, would SVR still be determined from the date of last dose?  I would think the "sustainability" would have to mean 6 months virus free rather than 6 months without meds.  Just saying.

[nygirl7]

<25 is a  better test than <43 preferably a test to <2 would be optimal but still guarantees nothing since the virus still could reside in the fibrosis of your liver.

If the meds were stopped at time A with detectible virus you would really need to have the interferon on board to kick in at this time.  I had a 'false' positive at my 4 week test and my doctor insisted it was that however I believe perhaps I was not 100% clear but that the immune system response kicked in and destroyed/suppressed whatever word you want to use at that time.

Of course I'll never know but I have been UND since 2006 and SVR since 2007 after treating for 72 weeks on SOC.  SVR is always done since day of last dose of meds.  it is six months free without the meds on board NOT six months UND.

[curiouslady1]

Yes.  But it appears to me that the value < 43 means just what it says.  The virus IS detectable.  It does not appear to have anything to do with the idiosyncracies of a particular lab.  See attagrl's recent note.  She had a value<25 which neither the investigators nor the lab considered to be undetectable.  She was designated "undetectable" when the word was used.  The reason I am making much of this point is that I know people that are wanting to quit therapy with a lab value of <43 because of the severe sides; considering themselves to be undetectable when they are not.  If any lab thinks that the individual is UND I would think they would use that word.

[nygirl7]

Look I've had many many PCRS over the last seven years and always when it said <315 or <615 or <2 or < 5 or <50 it never had a number in front of it and I was UND.

With the <43 test I was under the impression they told you that you were detectible but could not quantify below the 43 so they did not know the number.  Honestly it's not the best test at all when trying to determine quitting therapy early.

I dont know why anyone would go off protocol just believing they might achieve SVR when none of it has been tested and they aren't really sure when they were UND in the first place........yeah the sides s.u.c.k but having to retreat again someday with more fibrosis or cirrhosis might s.u.c.k even more.  Just sayin'

[lynda607]

LabCorp offers:

The NGI QuantaSure assay  which has a quantitative range of 2-2,000,000 IU/mL or 5-5,000,000 copies/mL.  The level of detection goes down to 2 IU/mL which is very sensitive.  Anything above 2 IU/mL will be reported as HCV RNA detected and numeric number will be assigned.

HCV RT-PCR Quantitative

The limit of detection of this assay is 7.1 IU/mL and the quantitative range of the assay is 43 to 69,0000.  The test cannot pick up anything below 7.1 IU/mL and the results will be reported below 43 IU/mL HCV RNA not detected. If HCV RNA is detected between 7.1 and 42 IU/mL it will be reported as below 43 IU/mL HCV RNA detected but a numeric number will not be assigned.  If 43 IU/mL or above it will be reported and HCV RNA detected and numeric number will be assigned.

The trial PCRs that use the under 25 IU/mL have a level of detection down to 10 IU/mL ( I think)  It can't detected HCV RNA below 10 IU/ml so if no HCV RNA detected it will be reported not detected.  The assay can't assign a numeric number for any HCV RNA detected between 10 IU/ml and 24 IU/mL so if HCV RNA is detected between 10 IU/mL and 24 IU/mL it will be reported as detected but below 25 IU/mL.  If RNA detected at 25 IU/mL or above it will reported as detected and numeric number will be assigned.

Info on the Quest Heptimax was given above.