GI-MAP Inaccurate for Pathogens + BioFire GI Panel

In the last couple of days, I was listening to the podcast of Michael Ruscio, NMD, DC (DrRuscio.com/Podcast) and he had an episode titled "Study Finds Functional Medicine Stool Testing is Inaccurate" that piqued my interest.

During that episode, Dr. Ruscio talks about the "GI-MAP" test from Diagnostic Solutions Laboratory and how "...it is an inaccurate test for assessing stool pathogens."

NOTE: For some reason, the podcast episode has disappeared from iTunes, though the audio file is still on my iPod. Dr. Ruscio usually has a corresponding blog entry on his website, but the one for this specific show has disappeared, too. However, thanks to our digital overlords at Google, I found a cached copy of the blog post -- complete with written transcript. [click here for cached copy]

Here's a few short clips I'm pasting:

Dr. Ruscio said...
Let’s go into detail about a study that looked at a popular functional medicine stool test and concluded that it was inaccurate. What does it mean? And what should we do about it? The name of the study in question is “Performance of a New Molecular Assay for the Detection of Gastrointestinal Pathogens”. This was published in open Access. So what does this study conclude? This study looked at Diagnostic Solutions Labs GI-MAP test and concluded that it is an inaccurate test for assessing stool pathogens. Why did they reach that conclusion? Purportedly because it suffers from an unacceptably low specificity at 27% for stool pathogens.

Dr. Ruscio said...
As we’ve discussed on the podcast in the past, poor specificity means there will be more false positives. So the test is inaccurate due to a high false positive rate. Is this a fair and truthful conclusion? Maybe. There’s debate over detection limit, meaning what threshold of detection of stuff in the stool should we consider positive as compared to acceptable background noise? There’s also a potential funding conflict. This study was funded in part by Doctor’s Data. So let’s unpack some of this and expand upon this issue of whether the GI-MAP stool test by Diagnostic Solutions Lab is an inaccurate test as this paper has concluded. The main point of contention, the key question, this is what we have to unpack, is regarding detection limit. The main response from the lab from Diagnostic Solutions Lab is regarding this issue of detection limit. DSL, the company that provides the GI map test, claims that their detection limits are better than the FDA endorsed ranges.

Dr. Ruscio said...
Now what’s important to mention here is that in this test, the GI-MAP was used next to another test that uses the FDA endorsed ranges called the BioFire Assay. In this study, there was correct identification of pathogens in the stool with the GI-MAP test. The issue is that they’re reporting a positive when the amount is less than what the FDA determines as the correct detection limit, risking a false positive.

There's more in the above-linked page that Google has cached.

After hearing Dr. Ruscio mention BioFire Diagnostics, I looked up their website and figured I should share their information:

The BioFire FilmArray Gastrointestinal (GI) Panel
https://www.biofiredx.com/products/the-filmarray-panels/filmarraygi

The BioFire website claims they test "...for 22 of the most common pathogens associated with gastroenteritis -- all from one patient sample and one easy to use reagent, with results available in about one hour."

They also report an "Overall 98.5% Sensitivity and 99.2% Specificity."

Should I see any retractions [about the GI-MAP test] by Dr. Ruscio, I'll be sure to update this thread accordingly.

Just FYI, in case any of this might be interesting or helpful to someone.

I got my GI Maps results back last week. Parawellness found Blasto in my stool. GI Maps did not. In addition, while I have significant dysbiosis and diagnosed SIBO along with recurrent loose stools, nothing really showed up in the GI Maps.

It seems like its an Ok test for picking up a handful of obvious pathogens we know shouldn't be there (although your post above seems to call the accuracy into question), I was left feeling like unless you've got one of those obvious baddies, the technology just isnt there to really quantify where and how a gut like mine is dysbiotic.

In addition, my bacteria levels for the different normal flora looked quite different than they did in my 2019 GI Maps. Ones were low that were previously high, and vica versa. Made me question the accuracy of it all.

I guess at the end of the day it doesnt matter, I just need to keep doing the keto and eating healthy and eventually it will heal. Would have been nice if it confirmed the blasto tho.

WalkingbyFaith said...
I am confused. It sounds to me like it would catch smaller amounts of pathogens in the sample. And they call that a false positive?

If I were to do testing for Lyme/co, I would want a lab that detected smaller quantities and caught the presence of the pathogens rather than a lab that only reported larger quantities and ignored the presence of lower numbers.

Did you read the full transcript? If not, it should provide a more detailed explanation. I didn't cut-and-paste the full transcript, as it's quite long.

I believe I read once that tests like that are time dependent. The closer you are to where the test is performed, the more accurate the test is. If it takes a day or two to get tested, the results are not accurate. It was something like a 3 to 6 hour window for the results to be accurate.

OK - i found a minute to read the transcript

in general, i have to agree with the points made by the author.

but the findings should come as no surprise to us

a test that has a lower threshold for positive throws up a higher number of positives is a simple and expected outcome.

what is the right level to set the threshold? - well the FDA-approved levels are typically based on acute cases of gastrointestinal pathogens - so may well be on the high/safe side for people who are chronically ill ...

on the other hand, if you keep setting the level lower and lower you will clearly have more and more positives and end up treating needlessly

you also have to look at who funded the study ie a direct competitor - and this competitor did not choose to compare their own equivalent product in the study - despite that being an easy thing for them to do.
that is less than transparent and should tell us they were aware of the likely outcome of that - and didn't want that published. Poor ethics in my view.

the basic issue is the same that exists for almost all functional medicine testing out there. any company can set up and market a test along with marketing claims of its utility that they are not required to prove, or even support with good evidence - despite the target market being vulnerable individuals.
this is morally wrong in my view. it should be legislated against to protect the vulnerable in our society.

in the UK - any test lab that is used by our nationalized health service has to pass regular 3rd party blind validation testing to show the test performs as stated.
we need something like this for all commercial functional medicine testing labs.

of course, there will be ins and outs - in that what constitutes a gold standard for tests shat are proprietary would need to be agreed - but left as it is - it is likely to become a race to the bottom as the article suggests.

by the way - my partner and I had a GI map test done a couple of years ago - along with a Ubiome test around the same time
in both our cases the results were not even in the same ballpark - in fact, they were diametrically opposed to one another.
an impossible result that means one or both tests were no better than random number generators - impossible to tell which
I wrote about it here - see post #26 onwards
https://forums.phoenixrising.me/threads/blastocystis-does-anyone-know-of-a-pcr-based-test-that-is-available.61265/page-2