Does XMRV Cause CFS?
Oct. 9th, 2009 10:41 pm![[personal profile]](http://s.dreamwidth.org/img/silk/identity/user.png){kind=small}
rbA bunch of people have linked me to articles about research documenting the presence of the XMRV retrovirus in CFS patients. Most of the articles are flat out stating that this will probably lead to a test and/or cure for CFS.
I wish these articles (especially ones aimed at a non-scientific audience) would clearly distinguish between correlation and causation. Here's a primer, for those who aren't clear on it:
As far as I can tell, currently these are what is published about the XMRV virus and CFS:
So as far as I can see, there's nothing there that even vaguely specifies causation is the most likely explanation for the infections. And yet most of the reporting is screaming "PROBABLE CFS CAUSE FOUND".
Yes, it's still possible that the XMRV is causing CFS but we'd need to do a huge amount more study over many years to prove it.
After watching reports like this come and go for 15 years, colour me jaded.
Ricky
ETA:
The previous-to-this "big thing" for CFS was the hydrogen sulphide urine test, here's an example article: ME: Proof that it isn't all in the mind?. If you look hard enough on the ProteaBioPharma FAQ page - they're the company marketing the test - this is now watered down to this:
Incidentally, I took the test last week and I test negative. The sickest person I know with CFS also tested negative. So ... take of that what you will.
I wish these articles (especially ones aimed at a non-scientific audience) would clearly distinguish between correlation and causation. Here's a primer, for those who aren't clear on it:
- Correlation
- Two things are correlated when they tend to happen together. The correlation does not say anything about whether one of these things caused the other one. My favourite example is that in the last 100 years the number of pirates has decreased and global warming has increased. This, obviously, does not mean that global warming is caused by a pirate shortage!
- Causation
- Two things are only causally linked if one of them makes the other one happen. For example, if I take my raw pizza and heat it enough then I end up with cooked pizza. Heating pizza causes cooking.
As far as I can tell, currently these are what is published about the XMRV virus and CFS:
- There's a higher percentage of CFS patients (an immunosuppressed population, remember) with XMRV than the percentage of affected controls.
- I can't find any research about XMRV in other immunosuppressed populations with known causes for the immunosuppression, so we don't know if the CFS stats are abnormal given the immune status of the subjects.
- There is known to be at least one other patient population with high infection rates - prostate cancer patients.
- There is a background infection level in healthy patients.
- Neither the prostate cancer patients nor the healthy patients have CFS (at least at present) or they would have been excluded from medical trials for confounding factors. (We'd need long-term prospective research to know whether these XMRV carriers develop CFS at higher rates than matched controls and that's unlikely to ever be done given the current political climate.)
- We already know that the CFS population has much higher than average rate of other infections common to immune suppressed populations. Things like rickettsia, chlamydia pneumoniase, and mycoplasma infections.
So as far as I can see, there's nothing there that even vaguely specifies causation is the most likely explanation for the infections. And yet most of the reporting is screaming "PROBABLE CFS CAUSE FOUND".
Yes, it's still possible that the XMRV is causing CFS but we'd need to do a huge amount more study over many years to prove it.
After watching reports like this come and go for 15 years, colour me jaded.
Ricky
ETA:
The previous-to-this "big thing" for CFS was the hydrogen sulphide urine test, here's an example article: ME: Proof that it isn't all in the mind?. If you look hard enough on the ProteaBioPharma FAQ page - they're the company marketing the test - this is now watered down to this:
Our preliminary results indicate that a strong proportion of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) patients present such dysbiosis, and test positive with the NMT test.
Incidentally, I took the test last week and I test negative. The sickest person I know with CFS also tested negative. So ... take of that what you will.
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cheers
Glee
on the other hand, the discovery that this arcane virus is more prevalent among CFS patients than among the general population could lead to further discoveries. (although what CF has to do with prostate cancer, i can't begin to imagine.)
in other news... i am leaving in a few hours for that pagan gathering i go to every year. i'll be without internet, or even phone, connectivity until Monday night (Tuesday morning yourtime).
*hugs*
And yes, it might lead to useful discoveries one day but on the other hand none of the previous infections found to co-occur with CFS have lead to useful discoveries yet so it probably won't. I don't deny there's a chance it'll be useful - it's just the insane hyperbole that gets me.
The previous-to-this "big thing" for CFS was the hydrogen sulphide urine test, here's an example article: ME: Proof that it isn't all in the mind?. If you look hard enough on the ProteaBioPharma FAQ page - they're the company marketing the test - this is now watered down to this:
Incidentally, I took the test last week and I test negative. The sickest person I know with CFS also tested negative. So ... take of that what you will.
I totally agree about the names for logical flaws being generally cool - I find it interesting to explore logical fallacies, cognitive biases, and cognitive distortions (links are to Wikipedia master lists). I know that being aware of them doesn't stop them from happening but at least being aware is the first step I think!
(although, paradoxically, i think i caught a cold.)
as for logical flaws... of course, nobody ever believes that they are committing a logical flaw, which is a logical flaw in itself! ;-)
It could be causing the damage but not be the cause of most of the symptoms for most people. No way to know unless we do a lot more testing.
A New Virus for Old Diseases?
http://www.sciencemag.org/cgi/content/ab
John M. Coffin, corresponding author
(no abstract)
Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome
http://www.sciencemag.org/cgi/content/ab
Judy A. Mikovits, corresponding author
The abstract seems a lot more cautious than the press reports, it concludes:
"These findings raise the possibility that XMRV may be a contributing factor in the pathogenesis of CFS."
It seems that the press reports are *probably* coming from a press release - newspapers don't often pick up stuff from new abstracts I don't think. I suspect it's the press release that's the main culprit in misinterpreting the significance... I'd love to know for sure though!
r
I'm thinking about getting tested for XMRV anyway, though. I'm in an environment where I can probably just request it, and hand over some blood -- I'm just curious what that test might reveal.
It seems like every five minutes someone in the news turns around and shouts "OMG researchers have found out FOR THE FIRST TIME EVAH that CFS TOTALLY isn't just a MADE UP DISEASE!1!!" .... and we've been doing this for decades now.
We _know_ it isn't a made-up disease. Get back to us when you have results!
Take care.
it would be really nice though if those of you at the deepest end of the coalface had a better quality of life - one where you could really "plan" a day2day living stance.
1. Science is one of the foremost interdisciplinary science mags in the world. Nature is also one of the top two. The fact that this study even made it into Science is a huge deal. It means the scientific community is incredibly impressed by the authenticity of the work. No other CFS article has been accepted in the past as far as I know.
2. I've been following Judy Mikovits and how she became involved with WPI and Dr. Dan Patterson. I have become confident that she is true to her word. She says a blood test will be out within 6 months. She also truly believes that there is a causal effect, although she is not able to explain it in full yet. When she further studied 300+ patient samples, XMRV was present either actively or antibodies were present, having already launched an attack and won, in 95% of blood samples. That, I believe, is truly worthy of note.
3. My last reason for feeling this "might" finally be a big key to the mystery is the WSJ reporting that the National Cancer Institute convened behind closed doors when they received this study because of their concern for public health.
So, I am sorry. I know what it's like to have article after article thrust into your face with what will "cure" you. I've received at least a hundred or more over time. And, always when you refuse or refute it, they give you that look like "well, you must not really want to get better if you aren't at least going to try it". But, truly, with this, for the first time ever, I am encouraged and hopeful. Primarily because this is a large enough deal in the scientific world that funding will be more readily available for research. If that is the only good that comes from it, that would be enough for me.
Heidi
Now, clearly 1/5th of us don't have lymphoma, so this sampling method and case definition, whatever it was, has got to be massively suspect.
Thanks - keep me updated :)
r
Extrapolating from the study, 12 times as many healthy people have XMRV, compared to patients with CFS.
Doesn't add up, but it may play a part in the disease.
Karen
p.s. I think of CFS patients not as 'immune suppressed', but as immune dysregulated. (TH1 / TH2 imbalance)
r