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Pilot study: "Identification of anti-citrullinated protein antibodies in ‪CFS‬" plus call for funds

Jonathan Edwards

Jonathan Edwards

"Gibberish"
Messages
5,256
ACPA has only become routine in the last ten years. It would probably not occur to a physician to test it on someone with established ME since the value of the test is really to predict clinical RA weeks or months before it becomes clinically obvious or to delineate an already overt arthritis. Maybe all PR members should get it done by Christmas!
 
M

msf

Senior Member
Messages
3,650
Looks promising, but as Prof. Edwards pointed out, it should have been easy to weed out RA patients from the controls. If they failed to do this, they may have failed to weed them out of the ME group too.
 
nandixon

nandixon

Senior Member
Messages
1,092
Jonathan Edwards said:
Maybe all PR members should get it done by Christmas!
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For people living in the US, in many states this test is available online, without the need to see a doctor (you just go to an available blood draw facility after ordering). For example, it's offered by DirectLabs under the test name:

Cyclic Citrullinated Peptide (CCP) Antibodies, IgG/IgA, Elisa

Cost is $83, and you can sometimes get that discounted with special offers or coupons.
 
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Snow Leopard

Snow Leopard

Hibernating
Messages
5,902
Location
South Australia
Jonathan Edwards said:
It would be easy to replicate in all ME/CFS service units and it would be worth checking out. I would like to see the actual readings for each patient before commenting on the data. Two positives in 25 controls is not quite as expected.
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On Wikipedia it is claimed the assays have a specificity of around 87.8% and 96.4%, so two false positives is not as far fetched as it may seem.

Having said that, I am not overly impressed by the findings of the pilot study.
 
nandixon

nandixon

Senior Member
Messages
1,092
Although preliminary, it's seems a little difficult to not find the results of the study significant, absent some gross errors in performing the testing.

A 5 or even 10% false positive rate in healthy controls seems relatively typical for ACPA testing. So 2 of 25 controls testing positive might be expected.

The Mayo Clinic is indicating that the false positive rate for ACPA for individuals with autoimmune diseases other than rheumatoid arthritis (RA), including for example systemic lupus erythematosus (SLE), may be about double the false positive rate for healthy persons.

Allowing for 1 or 2 (non-autoimmune) false positives among the patients, that leaves 5 or 6 true positive and/or non-RA autoimmune false positive patients - which is quite a large number out of 25 and which seems to require that either a significant number of the patients actually have RA, which seems unlikely, or that a large number have other autoimmune diseases - or that the ACPA may indeed be specifically positive for a subset of ME/CFS patients.

So, absent error, either way the results could be suggesting that the ACPA test may be useful in ME/CFS, if not as a true test for a subset of ME/CFS patients, then to indicate the possibility of autoimmune diseases other than RA. It'll be interesting to see what comes of this.
 
Scarecrow

Scarecrow

Revolting Peasant
Messages
1,904
Location
Scotland
nandixon said:
The Mayo Clinic is indicating that the false positive rate for ACPA for individuals with autoimmune diseases other than rheumatoid arthritis (RA), including for example systemic lupus erythematosus (SLE), may be about double the false positive rate for healthy persons.
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Struggling a little to understand the implications of that. If the false positive rate is different for healthy controls and autoimmune conditions other than RA, something must account for the difference. What could it be?
 
M

msf

Senior Member
Messages
3,650
I do not understand statistics, but my intuition (often wrong) tells me that you are more likely to get 50% positives in a given sample when the incidence in the general population is 20%, than you are to get 35% positives in a sample when the incidence in the general population is 5%. I guess what I am trying to say is that, since these antibodies seem quite common in the general population, the study does not seem to have enough power (which I guess is why they called it a pilot study).
 
U

user9876

Senior Member
Messages
4,556
Jonathan Edwards said:
ACPA has only become routine in the last ten years. It would probably not occur to a physician to test it on someone with established ME since the value of the test is really to predict clinical RA weeks or months before it becomes clinically obvious or to delineate an already overt arthritis. Maybe all PR members should get it done by Christmas!
Click to expand...

Its not a test recommended in the nice guidelines for ME which say
  • urinalysis for protein, blood and glucose

  • full blood count

  • urea and electrolytes

  • liver function

  • thyroid function

  • erythrocyte sedimentation rate or plasma viscosity

  • C-reactive protein

  • random blood glucose

  • serum creatinine

  • screening blood tests for gluten sensitivity

  • serum calcium

  • creatine kinase

  • assessment of serum ferritin levels (children and young people only).
Click to expand...
 
Old Bones

Old Bones

Senior Member
Messages
808
As mentioned in posts above, anti-ccp antibody testing is used as a diagnostic and prognostic tool in Rheumatoid Arthritis. It was used to diagnose me, in addition to symptoms, since my RF test was negative. According to the research, my moderately-high anti-ccp means I have an increased risk of rapidly-progressing RA with significant joint damage. But, that hasn't been my experience, thankfully -- at least not so far. Low-dose Methotrexate (chemo) is keeping my RA under control for longer than it usually does. This drug often stops working for RA after two years, I've been taking it for more than five. This leads me to wonder . . . . Since I only developed RA symptoms more than 20 years after my ME diagnosis, perhaps I really don't have RA, and my positive anti-ccp test is merely a result of long-term ME. My ME symptoms improved for the first few weeks on the chemo drug, but then returned. Perhaps this means I'd be a good candidate for rituximab. Wouldn't that be wonderful, assuming the drug is eventually approved for ME.
 
M

msf

Senior Member
Messages
3,650
Sorry, that was a bit ambiguous - I meant did anyone notice that the study mentioned in the thread title was done in Vermont. I then posted a link to a study that found anti-CCP antibodies in Lyme patients, but not in healthy controls. Vermont (along with Delaware) has the highest incidence of Lyme in the USA.
 
SOC

SOC

Senior Member
Messages
7,849
msf said:
Sorry, that was a bit ambiguous - I meant did anyone notice that the study mentioned in the thread title was done in Vermont. I then posted a link to a study that found anti-CCP antibodies in Lyme patients, but not in healthy controls. Vermont (along with Delaware) has the highest incidence of Lyme in the USA.
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Ah, thanks! Now I get it. :) That does raise some interesting questions about Lyme, CFS, and anti-CCP antibodies.
 
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