Aa
HR, Jim, mremeet, Goofy Dad, anyone that has knowledge of pcr testing?
Hi everyone,
Some of you have been following the saga of my "29" at week 12 as well as APK's. I do think/hope my 29 at week 12 is an "artifact" or false positive but for my own peace of mine, I want to comfirm that by getting the most sensitive and accurate pcr test available. Asked my doctor about it yesterday and the study can't provide one more sensitive than the one we've all been discussing but he told me I was welcome to get one on my own.
There's a lot of confusion in my mind surrounding these tests. Searched the archives and found something Goofy Dad posted in Nov.06
http://www.natap.org/2005/HCV/122805_04.htm
Conclusions: Among patients treated with combination therapy for chronic hepatitis C, the TMA test detects HCV RNA in all specimens that are Amplicor-positive, as well as an additional 21.6% that are Amplicor-negative. The increased sensitivity of the TMA test can be helpful in identifying patients with low levels of HCV RNA who are likely to relapse when therapy is stopped. Furthermore, among patients with EVR and a negative Amplicor test at W20, persistent detection of HCV with the TMA test during therapy predicts failure to achieve SVR.
*FDA-approved for detection of HCV RNA as evidence of active infection.
Can someone explain to me like I'm five years old what the above means. Also, HR posted on 11/12/06 the following:
(Continued below)
Some of you have been following the saga of my "29" at week 12 as well as APK's. I do think/hope my 29 at week 12 is an "artifact" or false positive but for my own peace of mine, I want to comfirm that by getting the most sensitive and accurate pcr test available. Asked my doctor about it yesterday and the study can't provide one more sensitive than the one we've all been discussing but he told me I was welcome to get one on my own.
There's a lot of confusion in my mind surrounding these tests. Searched the archives and found something Goofy Dad posted in Nov.06
http://www.natap.org/2005/HCV/122805_04.htm
Conclusions: Among patients treated with combination therapy for chronic hepatitis C, the TMA test detects HCV RNA in all specimens that are Amplicor-positive, as well as an additional 21.6% that are Amplicor-negative. The increased sensitivity of the TMA test can be helpful in identifying patients with low levels of HCV RNA who are likely to relapse when therapy is stopped. Furthermore, among patients with EVR and a negative Amplicor test at W20, persistent detection of HCV with the TMA test during therapy predicts failure to achieve SVR.
*FDA-approved for detection of HCV RNA as evidence of active infection.
Can someone explain to me like I'm five years old what the above means. Also, HR posted on 11/12/06 the following:
(Continued below)
Will Quest labs automatically run the Heptimax? My H has his bloodwork done at the local hospital but several blocks away is a Quest lab. His doc doesn't care where he gets his bloodwork done. The hospital runs a test that says Mayo Clinic UND <615 but doesn't give you any more specific information. He was UND <615 at 12 weeks. If you go to a Quest lab do you have to request a specific test or is doc's lab slip with PCR checked enough info for them? I'm very confused about these labs. The docs says UND is UND and that's what the research proves out, but we can have whatever test we want as far as he's concerned a PCR is a PCR. My insurance company says the same thing. Have there been studies that show a statistical correlation between UND <615 testers having a higher percentage of relapsers than UND< 5 or some other group tested to the lower numbers? H's doc says "no" but if I can find one he would be interested in reading it. He does appear to attend symposiums and attempt to stay on top of new trends and we're happy with him considering we live in a small town. He's open to conversation and we've had several regarding "what" UND really is. I'm the one that worries that H will be a relapser because of his liver bx (probable cirrohsis)
Thanks for the info. I'm going to look for that Chicago paper. An old beau of mine is a former NIH/Johns Hopkins HIV/HCV co-infectious disease specialist and I was sorely tempted to make contact after 20+ years to get some definitive answer to this testing question as it seems to be a sticking point with many of the mainstream docs. I made a similar argument with the doc based on what I've learned here. I'm considered an intelligent person ('though not a medicine "doc") and the doc conceded that the rationale/argument was sound, but felt simply that there was no substantive information to worry about searching for a more sensitive test. He simply deferred to whatever I felt "we" should do. I'll add Heptimax to my H's lab and have him go to Quest lab (doc gave me his entire year's worth of lab slips and just calls me and tells me what he wants to run so the reality is I can write/X anything I want). I'll sleep alot better if I feel that UND really is UND, right now I'm not convinced but I don't say a word to my H as he's feeling on top of the world (which in some respects he is at 13,000 ft. w/skis strapped to his feet right now). I am continually impressed by the depth of knowledge and conversation on this forum. I'm grateful to have stumbled on it. I'm also cheered by the fact that our family doc grills me every four months when I'm in to see him about this disease. I think he's feeling a tad guilty for not discovering this in my husband when his liver enzymes rose in 1988 and rose again in 1998. If only I knew then what I know now... sigh.....hopefully the family doc will be a smarter family doc.
I have read this thread and will try to explain the kenetics of the viral decay and how it will relate to the PCR testing and sensitivities. Then hopefully somebody like hepatitisresearcher can chime in and tell me if this is right.
It seems that there are 2 main slopes to viral reduction which are the following:
1-Initial quick drop in the first 24 hours of TX, this is due mostly to the initial kill of the virus directly and is due to the interferon mostly. Usually a 1 to 1.5 log reduction.
2-The next stage of viral reduction is usually represented by a logrithmic decay of the viral load and is typically linear along the log graph. This slope along with how long you treat will ultimately determine your chances of success. I think the slope of this line is due to your body's ability to kill the infected hypocrites (sp) and this can range from individual to individual.
Now to the good stuff:
To get a sustain response you need to drop you viral count to nearly zero. NOT YOUR BLOOD tests which only measure a mere fraction of the the amount of plasma in your body, but you whole body.
The amount of virus detected in your PCR represents a small fraction (1/10,000) of the viral copies in your total body. So say you have 9 copies (which is undetectable with a very sensitive test) you could have approx. 9 X 10,000 or 90,000 copies of virus in your system. That 90,000 needs to get pretty close to zero to get a sustained response. You need another 4 to 5 log drop of viral load to be clear.
So hypothetically speaking, the sensitivity of a PCR test to actually tell you if you are clear of the virus would in theory be 0.00001 IU/ml.
So when we speak of a test that goes to 5, 10, 30, or even 50, all these tests are relatively the same number because they are within one log of each other.
So to recap, somebody with a starting viral load of 1,000,000 would need an 11 log reduction to clear the virus. A (10 iu/ml)test would only measure a 5 log reduction, And a (50 iu/ml) test would only measure approx. a 4.75 log reduction. On a log scale these numbers are virtually the same.
Any thoughts?
I am also going 72 weeks.
It seems that there are 2 main slopes to viral reduction which are the following:
1-Initial quick drop in the first 24 hours of TX, this is due mostly to the initial kill of the virus directly and is due to the interferon mostly. Usually a 1 to 1.5 log reduction.
2-The next stage of viral reduction is usually represented by a logrithmic decay of the viral load and is typically linear along the log graph. This slope along with how long you treat will ultimately determine your chances of success. I think the slope of this line is due to your body's ability to kill the infected hypocrites (sp) and this can range from individual to individual.
Now to the good stuff:
To get a sustain response you need to drop you viral count to nearly zero. NOT YOUR BLOOD tests which only measure a mere fraction of the the amount of plasma in your body, but you whole body.
The amount of virus detected in your PCR represents a small fraction (1/10,000) of the viral copies in your total body. So say you have 9 copies (which is undetectable with a very sensitive test) you could have approx. 9 X 10,000 or 90,000 copies of virus in your system. That 90,000 needs to get pretty close to zero to get a sustained response. You need another 4 to 5 log drop of viral load to be clear.
So hypothetically speaking, the sensitivity of a PCR test to actually tell you if you are clear of the virus would in theory be 0.00001 IU/ml.
So when we speak of a test that goes to 5, 10, 30, or even 50, all these tests are relatively the same number because they are within one log of each other.
So to recap, somebody with a starting viral load of 1,000,000 would need an 11 log reduction to clear the virus. A (10 iu/ml)test would only measure a 5 log reduction, And a (50 iu/ml) test would only measure approx. a 4.75 log reduction. On a log scale these numbers are virtually the same.
Any thoughts?
I am also going 72 weeks.
If your doctor is receptive to discussing the possible benefit of testing at the lowest level possible, then I'd simply print out the studies referenced above by PDS and HR and then hand them to your doctor on your next visit. Use a highlighter to mark off the most salient statements, including:
"Among patients treated with combination therapy for chronic hepatitis C, the TMA (5-10 IU/ml) test detects HCV RNA in all specimens that are Amplicor-positive (50-100 IU/ml), as well as an additional 21.6% that are Amplicor-negative. The increased sensitivity of the TMA test can be helpful in identifying patients with low levels of HCV RNA who are likely to relapse when therapy is stopped. Furthermore, among patients with EVR and a negative Amplicor test at W20, persistent detection of HCV with the TMA test during therapy predicts failure to achieve SVR."
The benefit of a more sensitive test as described in this study seems pretty straightforward and common sensical. Hopefully your doctor will agree. And if he does you'll not only be helping yourself, but you'll be helping his future (and current) patients by bringing it to his attention as well. But even if he doesn't see the light, sounds like he won't object to you getting the more sensitive test anyway.
"Among patients treated with combination therapy for chronic hepatitis C, the TMA (5-10 IU/ml) test detects HCV RNA in all specimens that are Amplicor-positive (50-100 IU/ml), as well as an additional 21.6% that are Amplicor-negative. The increased sensitivity of the TMA test can be helpful in identifying patients with low levels of HCV RNA who are likely to relapse when therapy is stopped. Furthermore, among patients with EVR and a negative Amplicor test at W20, persistent detection of HCV with the TMA test during therapy predicts failure to achieve SVR."
The benefit of a more sensitive test as described in this study seems pretty straightforward and common sensical. Hopefully your doctor will agree. And if he does you'll not only be helping yourself, but you'll be helping his future (and current) patients by bringing it to his attention as well. But even if he doesn't see the light, sounds like he won't object to you getting the more sensitive test anyway.
Agreed mrmreet. I guess somewhere deep inside of me I just want to be right and "win" this one with the doc (and for my H's future well being) so I'm looking for intelligent support for my argument! I'd pretty much convinced myself I was right and was thinking I'd write up the lab slip as such. The tenatious pig headed part of me wants the "young whipper snapper doc" to concede and he just won't bite!
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