Dr Freeman, thank you answering my question in what may be redundant.
The “important take home” on your final in the message below resulted in an approximately 3% point in favor of undetected vs 15iu/ML detected in patients after 4 weeks on Sof/Led?
Thank you.

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When reading this study – and then isolating the results for patients without cirrhosis and a baseline VL of < 6,000,000 who received a full 12 weeks of LDV/SOF (Harvoni) – I find that the results look very good. Table 4 shows an overall 12 week therapy SVR rate of 94.3% (1924/2040) with higher success rates in sub-groups depending on APRI and FIB-4 scoring. The best number achieved was 96.6% (875/906) in patients with both a FIB-4 of ≤ 3.25 and a baseline VL < 6,000,000 IU/ml. Looking over the health profiles of the study’s patient population – I wonder how the results would have been if the participants had received treatment earlier in their lives. With early diagnosis and treatment – the success rates might have been even better. Will add that I found the cost/benefit discussion troubling. With the stratospheric price the Veteran’s Administration pays for HCV medicines here it seems both understandable and unacceptable at the same time. J.

Wow – Some very in depth reports there! Thank-you Dr F.

Am I right in seeing that Sofo/DAC has a tiny edge over Sofo/Led (ie 1%) for GT1s?
I tend to phase out with graphs a bit

Hi Sven,

Allowing for slight differences in the different brands of assay tests the actual testing is the same, the problem as you say is in the protocol of different labs and doctors in the way that results are reported and explained. I’ll try to explain my understanding of these tests as best I can.

First you need to understand that most modern tests like you received can accurately read down to 15iu/mL or sometimes 12iu/mL. The key word is accurately. They can read below that level and as you doctor says they will often read down to around 5-6 but between 5-6 and 15 they aren’t accurate. It is a bit like older car speedos which gave a good reading with 1mph divisions at 35mph but below 15mph there’s no markings and the needle wavers around a lot.

There are two types of test result: Qualitative and Quantitative.

Usually the test assay and equipment used is basically the same. The differences are:

Qualitative: a blood sample is taken and processed. It is then examined to see whether they can see the virus. If they can see it then they report it as Detected, if not then Undetected. End of test and the report gives you one of those answers. So it is a quick and dirty Yes/No test with no attempt to work out how much virus is present.

Quantitative: a blood sample is taken and processed. It is then examined to see whether they can see the virus. If they can see it then they go further and measure it against their scale and if it is above 15iu/mL then they will give an accurate result of 27 or 153 or whatever it is. If it is below 15 they can’t give you an accurate answer so they just say Detected <15 but the assumption is that it is probably somewhere between 5-6 and 15.

However, if when they check they can’t see any virus then sometimes it is reported as Undetected the same as a qualitative test but sometimes with the accuracy level of <15iu/mL of the test included. This is because they don’t accurately know where the lower level but they are confident that it must be less than 15. Some labs/doctors seem reluctant to put the Undetected result in writing and just report the <15 but then give a verbal undetected like your doctor appears to have.

The thing to keep in mind with these tests is that, as I think your doctor is trying to say, they can’t determine no virus, only that the virus levels are so low that the test can’t see it so it may or may not still be present which is what they mean by Undetected. If there is still virus then either our immune system will kill off the few remaining ones or it will start replicating again and eventually reach high enough levels to be detected and that is why we need to wait for a period of time such as SVR12 to see whether we are cured.

I hope that makes it a little clearer for you.

(I talk about ‘seeing’ the virus in these tests but really they are looking for viral RNA)