DGP accuracy study

[ironictruth]

Here is a link to a recent study showing the DGP to not be as reliable as previously thought. 

Open Original Shared Link

 I am not sure how to attach the full study.  The authors do say there were a few folks with Marsh one and two scores that were not included in the final celiac disease results. They also admit it's a small sample size and they were unable to track these individuals to see if they develop celiac in the future. The study does not look at first degree relatives or make reference to celiac genes.

Obviously, many members  here test positive only to the DGP and have biopsy proven celiac. However this study is meant to show that the test is not as reliable as previously thought.

 I am posting this with the hopes that members can refer to it when folks join the board who have positive DGP only and negative values on all other tests.  It may serve to encourage these individuals to continue follow-up testing, hopefully with an actual celiac specialist, so that they get an accurate diagnosis. Although this paper was done utilizing patients at Columbia University and Beth Israel Hospital, I have also heard similar accounts regarding DGP from staff at Mass General.

 

[Jmg]

Thanks for sharing, I find this research fascinating.

As you say the percentage picked up by DGP is small: 

Quote

 

RESULTS: Between the two institutions, 84 patients were identified with negative TTG IgA and positive DGP IgA or IgG who also had duodenal biopsies performed while maintaining a gluten-containing diet. Of these patients, 13 patients (15.5%; 95% CI 8.5-25.0%) were found to have celiac disease on duodenal biopsy.

CONCLUSIONS: DGP antibody testing can identify cases of celiac disease in TTG-negative individuals, although the low positive predictive value suggests that the yield may be low.

 

but at least it offers another pathway to diagnosis. Those 71 patients with positive DGP but negative biopsy may have had enough validation from the test to at least try the gluten free diet and if any of them had the same results I did I'm sure they're on it to this day. Even with the low percentages I still wish I'd had it done whilst I was on gluten as it may have helped me get a more definitive answer on my own case.

[ravenwoodglass]

So folks with Marsh 1 or 2 damage were not included in the study results. Were those folks told they had a false positive and to just keep eating gluten until their villi were totally destroyed? Some folks have villi destruction that is patchy and got missed. How many of those were told to ignore positive results and to just stay on gluten and here are some prescriptions to help with symptoms (but not stop the autoimmune process that is destroying their bodies and their lives). What about folks with DH that haven't had GI impact? Are they being told they don't have celiac and just advised to keep eating gluten and take Dapsone?  What about folks with positive tests that have mostly neuro impact and ataxia? Are those false positives also? I do wish doctors would acknowledge that Celiac is not just intestinal issues. Celiac is an full body autoimmune disorder that can impact many systems not just the gut.

[ironictruth]

Well, I did not do the study so I cannot answer the questions though the study pointed out the handful of Marsh 1 And 2 may continue to develop the disease  and possibly a subsequent study with follow-up overtime would be in order.

 

 The study was done using patients from two major Celiac Disease centers so I'm sure the doctors are well aware of issues such as gluten ataxia and DH.  You would have to contact them directly with your questions. 

 

There is another study on positive DGP IGA in folks with liver disease.  Some of these individuals were even gene negative.

 I am merely trying to post this here to draw attention to the fact that some folks who were considering not further testing May be unnecessarily restricting their diets and lifestyles.  

 I went gluten-free initially due to a mildly positive DGP, sibling with seronegative  But biopsy positive celiac, and I have the DQ2 gene. Then I underwent a 6 week gluten challenge, biopsy was negative,  doctor forgot to run the blood work  for a month during which I was gluten free and DGP only thing that came back again at a very weak positive when he finally ran it. I went on a gluten-free diet again for a number of months but started getting sick again last summer. Had inflammation in the small intestine but no blunting of villi. was positive on a combined DGP assay but negative on separated DGP assay.  ( the difference between these tests is actually listed in the study) I then cut out all processed foods and stOpped  going out to eat anywhere for several months and still kept getting sick. 

 I am now on a second lengthier gluten challenge  because I do feel the need to have a diagnosis to confirm Or rule out what's actually wrong with me.  had I magically started getting better when I cut gluten from my diet then It would have been a lot easier.  unfortunately that is not the case.  Although I am highly suspicious About my thyroid.

 When it comes to information about the new DGP test trust me, I am the first person to look at it and wonder how accurate it is, what else it may pick up,   whether or not it's actually being used by doctors, etc. 

 I will see if I can post the actual paper where you can see a little bit more about the kind of testing they used.

[ravenwoodglass]

9 minutes ago, ironictruth said:

Well, I did not do the study so I cannot answer the questions though the study pointed out the handful of Marsh 1 And 2 may continue to develop the disease  and possibly a subsequent study with follow-up overtime would be in order.

 

 The study was done using patients from two major Celiac Disease centers so I'm sure the doctors are well aware of issues such as gluten ataxia and DH.  You would have to contact them directly with your questions. 

 

There is another study on positive DGP IGA in folks with liver disease.  Some of these individuals were even gene negative.

 I am merely trying to post this here to draw attention to the fact that some folks who were considering not further testing May be unnecessarily restricting their diets and lifestyles.  

 I went gluten-free initially due to a mildly positive DGP, sibling with seronegative  But biopsy positive celiac, and I have the DQ2 gene. Then I underwent a 6 week gluten challenge, biopsy was negative,  doctor forgot to run the blood work  for a month during which I was gluten free and DGP only thing that came back again at a very weak positive when he finally ran it. I went on a gluten-free diet again for a number of months but started getting sick again last summer. Had inflammation in the small intestine but no blunting of villi. was positive on a combined DGP assay but negative on separated DGP assay.  ( the difference between these tests is actually listed in the study) I then cut out all processed foods and stOpped  going out to eat anywhere for several months and still kept getting sick. 

 I am now on a second lengthier gluten challenge  because I do feel the need to have a diagnosis to confirm Or rule out what's actually wrong with me.  had I magically started getting better when I cut gluten from my diet then It would have been a lot easier.  unfortunately that is not the case.  Although I am highly suspicious About my thyroid.

 When it comes to information about the new DGP test trust me, I am the first person to look at it and wonder how accurate it is, what else it may pick up,   whether or not it's actually being used by doctors, etc. 

 I will see if I can post the actual paper where you can see a little bit more about the kind of testing they used.

My post was not directed at you personally but an expression of my own frustration in the way that many medical professionals look for and at the diagnosis of celiac. Your posting research info is very much appretiated.  I was misdiagnosed for many long and painful years and am thankful that the diagnosis process is becoming better.  It does still have a long way to go though and many doctors are still very far behind in their knowledge. 

I do hope you get a resolution to the problems you are having and clear answers. I know all too well that frustration with being very ill and doctors not being able to tell you what is causing it.

[ironictruth]

Yes. Thanks. I am also amazed. Not sure I actually have celiac but at least now I can rule it out/in with an actual specialist. Because my first GI did not know about DGP, failed to draw blood work, and my second GI told me people with celiac just "get the runs".

So I am learning a lot about what folks have to go through for a diagnosis! of celiac either way.

Hopefully I just attached the paper.

Open Original Shared Link

[GFinDC]

It seems like another way to look at the positive DGP and negative biopsy is that DGP could be an early indicator of celiac disease.  Perhaps before much intestinal damage shows up.

[ironictruth]

2 minutes ago, GFinDC said:

It seems like another way to look at the positive DGP and negative biopsy is that DGP could be an early indicator of celiac disease.  Perhaps before much intestinal damage shows up.

Yes, that is implied as possible. Certainly should spur some additional studies.