Differences between European viral load values and U.S. values

[Dan J.]

I had an appointment with Hermans HIV doc yesterday. She was reading my latest t-cell & viral load results. In Europe they say less than 50 is undetectable. Back home my doc uses less than 400 as undetectable.  Why  is it like that? Cost? Is less than 400 really undetectable?

Dan

[bocker3]

HI Dan,

It depends which test is ordered.  The "ultrasensitive" test has a lower detectable limit of 50.  The "regular" (for lack of a better word) only goes down to 400.  I believe there is a "cost" issue between the two and I believe some doctors (mine for example) uses the 400 limit test initially and moves to the ultrasensitive test once on meds or if <400 without meds.

Hope that helps.

Mike

[bear60]

Dan
I cant answer that. However there was reference by someone to the fact that their health plan only paid for tests that would read to a minimum of 400.  So they would NEVER get a reading of less than 50.   I do get readings of less than 50.
 My guess is that it has nothing to do with European or US readings.

[manchesteruk]

I suspect it might just be different guidelines Dan.  The test I normally have here in the UK has a detectable limit of 40.  I can't imagine there being a big difference between 50 and 400 though?

[Cliff]

Hi Dan,

It doesn't have anything to do which country you are in, just the test your doctor/clinic orders.  All of my viral load tests done in the US were measured using an undetectable rate of 50.  I'm not sure it's makes that much of a difference, except for maybe when you are just becomming resistance to a med, maybe the 50 or less lab will pick it up sooner.

I hope you are having fun (or had fun if you're back in the States)!

Cliff

[lydgate]

The "regular" PCR VL test has a detectability threshhold of 400 copies -- i.e., you might have a count of 398, but that would show up as <400 or undetectable on that test. The "ultrasensitive" test most commonly used in the US has a detectability threshhold of 50, so any count under that would show up as <50 or undetectable on that particular test.

The former is usually used when people aren't on meds or the VL is suspected to be high, or at least not just in the three digit range. The latter is usually used when someone is on ARTs and the meds suppress viral loads to very low levels; it is more expensive (I'm not sure by how much). There are even more sensitive VL tests with detectability threshholds of 20 copies or lower, used normally only in research settings.

I guess it's possible that some HMOs or ASOs use the "regular" (not the ultrasensitive) test for everyone, whether on meds or not, because of cost or access issues. The obvious drawback is that then one can tell that there has been viral suppression to the 400 copy level but not if viral load has been suppressed even further. I don't know what difference that makes in clinical/practical terms; perhaps someone else (Rich, newt, Gerry) might know.

Hope that helps. And hope you're enjoying Belgium!

Jay

Edited for typos.

[newt]

No doctor should be ordering tests that only measure down to 400 copies for people on combo.  With a viral load betwen 50 and 500 copies there's enough virus to develop resistance.

The difference between 50 and 500 copies is the same as 50,000 and 500,000, a factor of 10.  This is important. The test measures virus in a fraction of your blood so 10 x more everywhere is a shit load of virus (grrrrrr! goes the virus)

Ultrasensitive viral load tests are (a) near enough as cheap (b) common, common, common these days.

- matt

[David_CA]

Speaking of European and US differences, what does +ve mean?  I see that used often with Europeans instead of the more common (over here, anyway) HIV+.

David

[LatinAlexander]

Well, I know nobody is asking me, but I am actually using "undetectable" =<40 (yes, the tests they do on me are that sensitive)

Alex

[Ann]

Hi David,

+ve just means positive. Not sure where they got it from, but there is a free magazine by that name.

Ann