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Taqman vs Heptimax
Numerous times Jim has recommended getting Heptimax or Quantasure # 140639 for vl tests until getting to undetected. For my week 4 vl tests my NP used TaqMan HCV Analyte-specific Reagents (qualitative?) and COBAS TaqMan 48 HCV.
I am still a little unclear about when a quantitative and when a qualitative test is warranted. The two Taqman tests I mentioned have different sensitivities - at this point, I think would just need to know the quantitative amount of the vl.
Bottom line question for me is, there is a Quest lab within driving distance from my house, should I insist on using the Heptimax for the week 8 test or are these Taqman tests good enough?
Thanks for any input.
smaug
I am still a little unclear about when a quantitative and when a qualitative test is warranted. The two Taqman tests I mentioned have different sensitivities - at this point, I think would just need to know the quantitative amount of the vl.
Bottom line question for me is, there is a Quest lab within driving distance from my house, should I insist on using the Heptimax for the week 8 test or are these Taqman tests good enough?
Thanks for any input.
smaug
it's OK, really.I also repeat myself all the time, as my wife reminds me ( always a pleasant surprise since I suspected she wasn't listening ..) hr on the other hand could repeat himself a bit more, imho
Since the subject of my "repeated" endorsement of Quest's "Heptimax" has been raised, I'll take a moment to repeat why I've often recommended Heptimax..
There are numerous tests to choose from when measuring viral load and it's not that one is necessarily better than another, but rather that one is more appropriate than another in different scenarios.
Starting with pre-treatment -- there's no reason why you shouldn't take a simple Bdna with sensitivity or around 600 IU/ml. These tests are frequently given pre-treatment.
Once treatment starts, you want a sensitive quantitative test that will go well below 60. There are many to choose from.
Once you become UND via a sensitive quantitative, you could stick with that or switch over to a sensitive qualitative which might be more cost efficient or which you otherwide might prefer.
So, in a sense, you could reasonably have several different kinds of tests during the course of treatment. In my case, I started with a Bdna, then switched to a sensitive quantiatitive (Heptimax) and then switched to a sensitive qualitative (Quest's HCV RNA TMA QUAL).
The reason I often recommend "Heptimax" is because it reasonably does all the other tests can do in one test. In other words you can use it before, during or after treatment, regardless of what your viral load is. The alternative is to post a long dissertation on what tests are best used at what times during treatment. We've had a couple of threads on this, and many stated in those threads that they found the subject confusing.
So...if you want to do your homework, there are many good tests to take. Just make sure you take the right test at the right point in indivdual particular treatment cycle. If you're not so motivated, or if the whole subject confuses you -- then Quest's Heptimax is an excellent all-around choice. Of course, if you have 100% faith in your medical team, then just take whatever test they recommend and when they recommend you to take them.
On deference to HR, the test he recommends is NGI's Quantasure, not the Quantasure Plus which is done in a different lab. The only problem I see with Quantasure is that it's upper limit is only around 2 million (by memory so please check this out) -- so if you had a very high pre-treatment viral load it would not quantify the viral load. Heptimax, on the other hand has a very high upper limit (50 million?) so you would not have this issue. Again, a good test for all circumstances. So if LabCorp is your lab of choice -- then a reasonable strategy might be to start with Quantasure Plus pre-treatment and switch over to NGI's Quantasure at a point your viral load drops under 2 million IU/ml, or when you think it reasonably should be below that point.
-- Jim
There are numerous tests to choose from when measuring viral load and it's not that one is necessarily better than another, but rather that one is more appropriate than another in different scenarios.
Starting with pre-treatment -- there's no reason why you shouldn't take a simple Bdna with sensitivity or around 600 IU/ml. These tests are frequently given pre-treatment.
Once treatment starts, you want a sensitive quantitative test that will go well below 60. There are many to choose from.
Once you become UND via a sensitive quantitative, you could stick with that or switch over to a sensitive qualitative which might be more cost efficient or which you otherwide might prefer.
So, in a sense, you could reasonably have several different kinds of tests during the course of treatment. In my case, I started with a Bdna, then switched to a sensitive quantiatitive (Heptimax) and then switched to a sensitive qualitative (Quest's HCV RNA TMA QUAL).
The reason I often recommend "Heptimax" is because it reasonably does all the other tests can do in one test. In other words you can use it before, during or after treatment, regardless of what your viral load is. The alternative is to post a long dissertation on what tests are best used at what times during treatment. We've had a couple of threads on this, and many stated in those threads that they found the subject confusing.
So...if you want to do your homework, there are many good tests to take. Just make sure you take the right test at the right point in indivdual particular treatment cycle. If you're not so motivated, or if the whole subject confuses you -- then Quest's Heptimax is an excellent all-around choice. Of course, if you have 100% faith in your medical team, then just take whatever test they recommend and when they recommend you to take them.
On deference to HR, the test he recommends is NGI's Quantasure, not the Quantasure Plus which is done in a different lab. The only problem I see with Quantasure is that it's upper limit is only around 2 million (by memory so please check this out) -- so if you had a very high pre-treatment viral load it would not quantify the viral load. Heptimax, on the other hand has a very high upper limit (50 million?) so you would not have this issue. Again, a good test for all circumstances. So if LabCorp is your lab of choice -- then a reasonable strategy might be to start with Quantasure Plus pre-treatment and switch over to NGI's Quantasure at a point your viral load drops under 2 million IU/ml, or when you think it reasonably should be below that point.
-- Jim
Smag,
By memory I think TaqMan is fairly sensitive but would want to know the acutal sensitivity to comment. Also, your pre-tx viral load and vl history impact on what test to take. For that reason I often recommend Heptimax because it can be taken before, after or during treatment -- sort of a one test for all instances kind of thing. Other tests are equally as good but would have more specific applications -- for example a sensitive qualtiatitve after UND.
Willing: Notwithstanding Jim's repeated endorsement of Quest/Heptimax/Quantasure there are many, many, well-regarded testing options
---------------------------
Actually it is HR "repeated" endorsements of Quantasure you are referring to -- while I have on occasion just passed on his recommendations which he elaborates on whenever a viral load test thread comes up and he's around. But is it really necessary to use the adjective 'repeated" with either myself or HR? You repeat yourself quite a lot as well -- as do most of us -- unless we change our opinions. If what you really mean is that you agree with a particular opinion, then why don't you just say it and why..
-- Jim
By memory I think TaqMan is fairly sensitive but would want to know the acutal sensitivity to comment. Also, your pre-tx viral load and vl history impact on what test to take. For that reason I often recommend Heptimax because it can be taken before, after or during treatment -- sort of a one test for all instances kind of thing. Other tests are equally as good but would have more specific applications -- for example a sensitive qualtiatitve after UND.
Willing: Notwithstanding Jim's repeated endorsement of Quest/Heptimax/Quantasure there are many, many, well-regarded testing options
---------------------------
Actually it is HR "repeated" endorsements of Quantasure you are referring to -- while I have on occasion just passed on his recommendations which he elaborates on whenever a viral load test thread comes up and he's around. But is it really necessary to use the adjective 'repeated" with either myself or HR? You repeat yourself quite a lot as well -- as do most of us -- unless we change our opinions. If what you really mean is that you agree with a particular opinion, then why don't you just say it and why..
-- Jim
I went through the exact same questions and thoughts you have...Ultimately I decided to continue to use the rna rt-pcr (taqman-mayo clinic down to 10 iu) I actaully had both tests you described at the same blood draw and got 2 different results, the one down to 615 (HCV quant) gave a 1248 iu/ml, the one down to 10 (RNA Qual) gave a result of 2000 iu/ml...The coice is up to you, one thing I would consider, since you're doc "is" dose adjusting, is how long it will take to get the results from Labcorp or Quest vs. the 3 days it takes to get back the Mayo test results. Either way, I'm sure your NP will write a script is you want it....
Pro
Pro
taqman is a component of real-time pcr, a well-regarded technique for quantifying hcv rna. A good, free-acces, recent summary of available hcv tests and their value in guiding tx is
Molecular Diagnostics of Hepatitis C Virus Infection
by Scott and Gretch. There's a copy here
http://jama.ama-assn.org/cgi/content/full/297/7/724?ck=nck
The review also discusses quant vs qual. Basically qual simply confirms presence. On the other hand, during the early stages of tx, before rna becomes und, the decrease measured by quant tests indicate one's response to the meds.
Notwithstanding Jim's repeated endorsement of Quest/Heptimax/Quantasure there are many, many, well-regarded testing options. Eg from that review
"A critically important advance in molecular diagnostics has been the adaptation of real-time PCR methods to quantify HCV RNA. Using TaqMan technology, real-time PCR yields quantitative results with comparable sensitivity to qualitative tests. In addition, real-time PCR can accurately quantify HCV RNA levels over a linear range exceeding 6 logs (ie, 10 IU/mL to 100 million IU/mL) for purposes of therapeutic monitoring (Table 2).36 Therefore, a single test result serves the purpose of both quantitative and qualitative HCV NATs. The assay is faster and more cost-effective than the other techniques and has already replaced other NAT testing platforms at many institutions. "
In fact, for those who care about the details, standardized tests like Bayer's Versant and Roche's COBAS line are assessed and compared by many independent laboratories and thus reliable measurement of their range and false positive/negative rates is more readily available than for in-house tests like Quest's heptimax.
Molecular Diagnostics of Hepatitis C Virus Infection
by Scott and Gretch. There's a copy here
http://jama.ama-assn.org/cgi/content/full/297/7/724?ck=nck
The review also discusses quant vs qual. Basically qual simply confirms presence. On the other hand, during the early stages of tx, before rna becomes und, the decrease measured by quant tests indicate one's response to the meds.
Notwithstanding Jim's repeated endorsement of Quest/Heptimax/Quantasure there are many, many, well-regarded testing options. Eg from that review
"A critically important advance in molecular diagnostics has been the adaptation of real-time PCR methods to quantify HCV RNA. Using TaqMan technology, real-time PCR yields quantitative results with comparable sensitivity to qualitative tests. In addition, real-time PCR can accurately quantify HCV RNA levels over a linear range exceeding 6 logs (ie, 10 IU/mL to 100 million IU/mL) for purposes of therapeutic monitoring (Table 2).36 Therefore, a single test result serves the purpose of both quantitative and qualitative HCV NATs. The assay is faster and more cost-effective than the other techniques and has already replaced other NAT testing platforms at many institutions. "
In fact, for those who care about the details, standardized tests like Bayer's Versant and Roche's COBAS line are assessed and compared by many independent laboratories and thus reliable measurement of their range and false positive/negative rates is more readily available than for in-house tests like Quest's heptimax.
For me, a qualitative at 4 weeks is sufficient as long as I'm testing UND or within the sensitivity range. If I'm above that, I'll want a quantitative PCR to tell me how much I'm above the upper limit of the qualitative so that I'll know exactly how I'm doing all the way through treatment. I believe in tweaking treatment if you can and also....I prefer to be well aware of all my realities as I go.
For someone who's not going to change ANYTHING on their treatment and nothing will change as a result of knowing their viral load at 4 weeks or 8 weeks or anywhere until 12 weeks...and for those who would rather not know how it's going until that 12 week mark...well then a quantitative at 12 weeks is vital and I guess qualitative is okay up until then.
For most though...unless you're below that qual amount, I would prefer to see quant PCR's at specific intervals all along. It just gives you SO much information and frankly so many applications of that information that are unknown until the time comes where it becomes useful. If the quant PCR tests haven't been done, then you do NOT have that information and you can't go back and do the tests. For example, you'll know if you dropped to a certain amount at 4 weeks and then just stayed there...you'll know if your drop is steady...you'll just have so much more of an accurate picture to make decisions with ongoing. Particularly if, hopefully not, you treat more than once. To me.. the more information the better.
So...to nutshell, to me a qual test is fine if you're below the testing amount in VL. Otherwise, a quant PCR is incredibly important in my opinion.
Trish
For someone who's not going to change ANYTHING on their treatment and nothing will change as a result of knowing their viral load at 4 weeks or 8 weeks or anywhere until 12 weeks...and for those who would rather not know how it's going until that 12 week mark...well then a quantitative at 12 weeks is vital and I guess qualitative is okay up until then.
For most though...unless you're below that qual amount, I would prefer to see quant PCR's at specific intervals all along. It just gives you SO much information and frankly so many applications of that information that are unknown until the time comes where it becomes useful. If the quant PCR tests haven't been done, then you do NOT have that information and you can't go back and do the tests. For example, you'll know if you dropped to a certain amount at 4 weeks and then just stayed there...you'll know if your drop is steady...you'll just have so much more of an accurate picture to make decisions with ongoing. Particularly if, hopefully not, you treat more than once. To me.. the more information the better.
So...to nutshell, to me a qual test is fine if you're below the testing amount in VL. Otherwise, a quant PCR is incredibly important in my opinion.
Trish
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