Diagnosis of mast cell activation syndrome: a global “consensus-2”, 2020, Afrin et al

Free full text: https://www.degruyter.com/view/jour...dx-2020-0005/article-10.1515-dx-2020-0005.xml

 

This sentence seems to sum up the paper and the whole MCAS situation:

 

Yes, but what does it mean?
Superficially the situation might be similar to ME, where arguing about criteria gets in the way of helping a group of people with a clinical syndrome we know exists. But we do not know that a syndrome due to one or more (unspecified) problems with mast cell activation exists. If the prevalence is estimated to be somewhere between less than 1% - people with disorders of tryptase levels maybe - to 17% then we can be pretty sure nobody actually nows if this exists or not. And why is one of the authors someone who is an advocate for Ehlers-Danlos syndrome, which has nothing to do with MCAS?

 

According to Wikipedia Afrin suggests that MCAS could cause spontaneous human combustion, presumably there is no such thing and that cannot be a valid theory? I recall reading a very long article by him years ago on MCAS dymptoms and thinking it sounded like me until I got to the end and he brought in spontaneous human combustion and then I discounted the whole thing.

 

Don't know if this paper warrants an own thread --the first author is also a co-author of the 'golbal consensus':
https://twitter.com/user/status/1358474398706106370

Code:

https://twitter.com/awgaffney/status/1358474398706106370/CODE]

https://twitter.com/user/status/1358474406859862020

Code:

https://twitter.com/awgaffney/status/1358474406859862020

Edit: clarity and fixed links.

Edit 2: No idea how the tweeter's stance on other evidence in LC is, I just thought the info about Afrin's and Weinstock's and also Theoharides' COI, if true, is interesting.

 

In essence, this consensus statement (which mostly included clinicians and few researchers) is a rebuttal of the restrictive “consensus-1” diagnostic criteria that were established by mastocytosis experts (Valent et al 2010), which are as follows per their 2019 update:

The authors mainly critique:

• that it requires a response to therapy (antihistamines, leukotriene antagonists or cromolyn) rather than permits it

• the absence of evidence for the “20% + 2” tryptase level criterion

• an over-reliance on tryptase at the detriment of other mast cell mediators

• the restrictive set of symptoms that leaves out many of those that they consider to be linked to MCAS

• the small panel of experts that devised the criteria at an invitation-only conference in 2010

Instead, the authors propose that the more permissive “consensus-2” diagnostic criteria elaborated by the senior author (Molderings et al 2017) be broadly adopted:

They are also very critical of the American Academy of Allergy, Asthma and Immunology’s diagnostic criteria (2019), which are based on the consensus-1 but contain episodes of anaphylaxis as an added required criterion. Indeed, they argue that most MCAS patients do not have such episodes and that this requirement deprives many of them from a diagnosis and subsequent treatment.

The AAAAI recommends the following diagnostic tests, probably based on this 2017 review (see Table 3):

Unlike both consensus statements, they do not mention heparin.

Finally, the figure of the 17% prevalence rate comes from a single 2013 paper by Molderings, where 266 healthy controls were recruited in a German city (out of 1000 persons randomly contacted) and where 45 of them (17%) fulfilled the original “consensus-2” criteria published in 2011.

 

I talked briefly with a clinical lead consultant in allergology and expert for the French Health and Food Security Agency.

He mentioned that he has seen about 10 cases of MCAS in almost 3 decades (as diagnosed by serum tryptase and urinary metabolites of histamine, i.e. as per the AAAAI / consensus-1 diagnostic tests) and that it seems to be as rare as actual mastocytosis.

He believes that in the US, there may be sampling bias stemming from the diagnostic tests for food allergies, which are based on commercial extracts rather than problematic foods directly.