Quantcast

Subscribe to:
POZ magazine
E-newsletters
Join POZ: Facebook MySpace Twitter Pinterest
Tumblr Google+ Flickr MySpace
POZ Personals
Sign In / Join
Username:
Password:
Welcome, Guest. Please login or register.
August 22, 2014, 04:22:13 AM

Login with username, password and session length


Members
Stats
  • Total Posts: 635579
  • Total Topics: 48218
  • Online Today: 214
  • Online Ever: 585
  • (January 07, 2014, 02:31:47 PM)
Users Online
Users: 2
Guests: 138
Total: 140

Welcome


Welcome to the POZ/AIDSmeds Community Forums, a round-the-clock discussion area for people with HIV/AIDS, their friends/family/caregivers, and others concerned about HIV/AIDS.  Click on the links below to browse our various forums; scroll down for a glance at the most recent posts; or join in the conversation yourself by registering on the left side of this page.

Privacy Warning:  Please realize that these forums are open to all, and are fully searchable via Google and other search engines. If you are HIV positive and disclose this in our forums, then it is almost the same thing as telling the whole world (or at least the World Wide Web). If this concerns you, then do not use a username or avatar that are self-identifying in any way. We do not allow the deletion of anything you post in these forums, so think before you post.

  • The information shared in these forums, by moderators and members, is designed to complement, not replace, the relationship between an individual and his/her own physician.

  • All members of these forums are, by default, not considered to be licensed medical providers. If otherwise, users must clearly define themselves as such.

  • Forums members must behave at all times with respect and honesty. Posting guidelines, including time-out and banning policies, have been established by the moderators of these forums. Click here for “Am I Infected?” posting guidelines. Click here for posting guidelines pertaining to all other POZ/AIDSmeds community forums.

  • We ask all forums members to provide references for health/medical/scientific information they provide, when it is not a personal experience being discussed. Please provide hyperlinks with full URLs or full citations of published works not available via the Internet. Additionally, all forums members must post information which are true and correct to their knowledge.

  • Product advertisement—including links; banners; editorial content; and clinical trial, study or survey participation—is strictly prohibited by forums members unless permission has been secured from POZ.

To change forums navigation language settings, click here (members only), Register now

Para cambiar sus preferencias de los foros en español, haz clic aquí (sólo miembros), Regístrate ahora

Finished Reading This? You can collapse this or any other box on this page by clicking the symbol in each box.

Author Topic: VIRAL LOAD TEST ERROR MARGIN  (Read 1428 times)

0 Members and 1 Guest are viewing this topic.

Offline newbie76

  • Member
  • Posts: 238
VIRAL LOAD TEST ERROR MARGIN
« on: October 01, 2007, 05:02:13 PM »
Hello there. I have read in various literature that the Viral Load test has a margin of error and here in the UK they seem to always make the example that if there's a shift between one test and another from 5000 to 15000 it doesn't necessarily mean that anything is wrong as a 3-fold increase is within the margin error of the test.

However an increase from 5000 to 25000 instead means that the VL has actually increased.

Up to here I am ok.

What I don't understand though is, does the same principle then apply for higher nubers then?? For example, if A VL of 50.000 becomes 150.000 is that still not worrying because it's a 3-fold increase and therefore withing the error margin or?

 ???
« Last Edit: October 01, 2007, 05:29:35 PM by newbie76 »
25th Apr 07: The worst day of my life
27th Apr 07: cd4 202 14%
30th Apr 07: cd4 126 18% VL 110000
19th May 07: Started Truvada/Sustiva
20th Jun 07: cd4 218 25% VL 435
13th Aug 07: cd4 374 20% VL 64
20th Dec 07: cd4 435 24% VL <50
20th Oct 08: cd4 725 31% VL <50
30th Nov 09: cd4 725 30% VL <50
01st Nov 10: cd4 755 33% VL<50
11th Nov 11: cd4 754 32% VL<50
01st May 12: cd4 864 40% VL<50
01st May 13: cd4 615 VL 609 :-/
14th May 13: VL <50

Offline newt

  • Member
  • Posts: 3,878
  • the one and original newt
Re: VIRAL LOAD TEST ERROR MARGIN
« Reply #1 on: October 01, 2007, 05:25:24 PM »
Ok

maths..

You are right, the margin of error for a current viral load test is a factor of 3.  That means the result number indicates the middle of a range from 1/3rd the figure to 3 x the figure, for example:

Viral load result 50,000 ... Range 17,000-150,000

Okay, but ain't a viral load of 150,000 copies/mL massively more virus than 50,000?

No.

You can express viral load a different way, as a log value.  +/- half a log is considered (the beginning of) a significant change.

17,000 = log 4.2.
50,000 has a log value of 4.7.
150,000 = log 5.2 (rounding a bit). 

So both 17k and 150k are within half a log of 50k.

If you wanna convert your viral load into logs on Google. Just type "log(viral_load_number_here)" into the search box...eg "log(50)" returns 1.69 << undetectable  :)

A rough and simple way is to do viral load to logs is lose the 0 of the end of the viral load count. This is the same as a 1 log drop..eg log 150,000 = 5.2, log 15,000 = 4.2.

Newbie 76... hello :)... in your case a change from 5,000 to 25,000 may be significant, but then it may not. It's a change of 0.7 log. Really you need at least 1 more viral load to judge. 5,000 indicates a viral load that could be as high as 15,000 and 25,000 one that could be as low as 8,500, so the margin of accuracy for these two tests overlaps.

Hope this helps

- matt
"The object is to be a well patient, not a good patient"

Offline megasept

  • Member
  • Posts: 478
  • Steven here...
Re: VIRAL LOAD TEST ERROR MARGIN
« Reply #2 on: October 01, 2007, 05:34:50 PM »
Ok

maths..
Hope this helps

- matt


Matt: I have never understood logs, now I think I might finally get it. Once again thanks for spreading useful knowledge here and everywhere throughout the land.

 8) -megasept

Offline newbie76

  • Member
  • Posts: 238
Re: VIRAL LOAD TEST ERROR MARGIN
« Reply #3 on: October 01, 2007, 05:35:54 PM »
Thank you newt... I don't understand everything you say, but I understand that a change from 50000 to 150.000 is within the error margins of the test and that answer my question!

By the way, my VL was 64 at the last count, not 25.000! That was just an example to see if I understood correctly!

Thank you!

25th Apr 07: The worst day of my life
27th Apr 07: cd4 202 14%
30th Apr 07: cd4 126 18% VL 110000
19th May 07: Started Truvada/Sustiva
20th Jun 07: cd4 218 25% VL 435
13th Aug 07: cd4 374 20% VL 64
20th Dec 07: cd4 435 24% VL <50
20th Oct 08: cd4 725 31% VL <50
30th Nov 09: cd4 725 30% VL <50
01st Nov 10: cd4 755 33% VL<50
11th Nov 11: cd4 754 32% VL<50
01st May 12: cd4 864 40% VL<50
01st May 13: cd4 615 VL 609 :-/
14th May 13: VL <50

Offline Moffie65

  • Member
  • Posts: 1,755
  • Living POZ since 1983
Re: VIRAL LOAD TEST ERROR MARGIN
« Reply #4 on: October 01, 2007, 05:41:14 PM »
Well Newt, I FINALLY GOT IT!!!!!!!!! 

Thanks so very much.

Love,

P.S. Yes guys, I've been + for 24 years and never understood it like I do now, so yes, you are always learning!
The Bible contains 6 admonishments to homosexuals,
and 362 to heterosexuals.
This doesn't mean that God doesn't love heterosexuals,
It's just that they need more supervision.
Lynn Lavne

Offline newt

  • Member
  • Posts: 3,878
  • the one and original newt
Re: VIRAL LOAD TEST ERROR MARGIN
« Reply #5 on: October 01, 2007, 06:02:23 PM »
I blush  :-[

Handy links

Roche's HIV viral load slide rule with conversion widget, table << possible to analyse difference in 2 HIV viral loads

Janis & Friends hepatitis C viral loads with tables, terms explained and conversion factors for when comparing results from different tests

- matt
« Last Edit: October 01, 2007, 06:30:19 PM by newt »
"The object is to be a well patient, not a good patient"

Offline tsw923

  • Member
  • Posts: 174
Re: VIRAL LOAD TEST ERROR MARGIN
« Reply #6 on: October 04, 2007, 12:25:27 AM »
Matt,

Thanks for the links and the explanation, but maybe I'm just too tired for it to sink in.  Please tell me if this is correct.  On my last test my VL was <75.  On the test before that my VL was <50.  My doctor told me not to worry as the 'sensitivity of the test' was not the same (I switchted health plans and therefore labs).  But back to the point, if I use google the log numbers are 1.70 and 1.88 respectively (rounding up).  So the difference is -.18.  And that's where I get lost.  Are we saying that it is statistically insignificant as it is not more than a 1/2 log difference?

Sorry -- I muddled and sleepy,

Ty
Help find a cure for leukemia, lymphoma, and other blood-related cancers by sponsoring me as I walk a 1/2 marathon as a part of the Maryland chapter of Team in Training.  To find out more and to donate, please click on the following site:  http://www.active.com/donate/tntmd/tswtntmd

Offline milker

  • Member
  • Posts: 4,034
  • Protected phone sex
Re: VIRAL LOAD TEST ERROR MARGIN
« Reply #7 on: October 04, 2007, 12:36:51 AM »
tsw,

both tests show undetectable. You have 0 to 50 or 0 to 75 copies of the virus in the blood sample that was taken. You cannot correlate test sensitivity to your test results.

Milker.
mid-dec: stupid ass
mid-jan: seroconversion
mid-feb: poz
mar 07: cd4 432 (35%) vl 54000
may 07: cd4 399 (28%) vl 27760
jul 07: cd4 403 (26%) vl 99241
oct 07: cd4 353 (24%) vl 29993
jan 08: cd4 332 (26%) vl 33308
mar 08: cd4 392 (23%) vl 75548
jun 08: cd4 325 (27%) vl 45880
oct 08: cd4 197 (20%) vl 154000 <== aids diagnosis
nov 2 08 start Atripla
nov 30 08: cd4 478 (23%) vl 1880 !!!!!!!!!!!!!!!!!!!!!!!!!!
feb 19 09: cd4 398 (24%) vl 430 getting there!
apr 23 09: cd4 604 (29%) vl 50 woohoo :D :D
jul 30 09: cd4 512 (29%) vl undetectable :D :D
may 27 10: cd4 655 (32%) vl undetectable :D :D

Now accepting applications from blowjob ninjas™

Offline tsw923

  • Member
  • Posts: 174
Re: VIRAL LOAD TEST ERROR MARGIN
« Reply #8 on: October 04, 2007, 09:45:07 PM »
Milker,

Thanks for letting me know.  I guess I didn't know that there was different sensitivities to this particular test.  Is there any way I can know the name of the test that is being taken.  I'm getting over being embarrassed when I go in to give blood for the tests and more interested in what they are supposed to be taking.

Ty
Help find a cure for leukemia, lymphoma, and other blood-related cancers by sponsoring me as I walk a 1/2 marathon as a part of the Maryland chapter of Team in Training.  To find out more and to donate, please click on the following site:  http://www.active.com/donate/tntmd/tswtntmd

 


Terms of Membership for these forums
 

© 2014 Smart + Strong. All Rights Reserved.   terms of use and your privacy
Smart + Strong® is a registered trademark of CDM Publishing, LLC.