WHAT’S NEW
Less invasive, less costly diagnosis of celiac disease in adults
In adults with symptoms suggestive of CD, the diagnosis can be made with a high level of certainty if a serum tTG-IgA titer is ≥ 10 times the ULN. Through informed, shared decision making in the presence of such a finding, patients may accept a serologic diagnosis and forgo an invasive EGD with biopsy and its inherent costs and risks. Indeed, if the majority of patients with CD are undiagnosed or underdiagnosed, and there exists a minimally invasive blood test that is highly cost effective in the absence of “red flags,” the overall benefit of this path could be substantial.
CAVEATS
“No biopsy” does not mean no risk/benefit discussion
While the PPVs are quite high, the negative predictive value varied greatly: 13%, 98%, and 10% for Cohorts 1, 2, and 3, respectively. Therefore, although serum tTG-IgA titers ≥ 10 times the ULN are useful for diagnosis, a negative result (serum tTG-IgA titers < 10 times the ULN) should not be used to rule out CD, and other testing should be pursued.
Additionally (although rare), patients with CD who have IgA deficiency may obtain false-negative results using the tTG-IgA ≥ 10 times the ULN diagnostic criterion.7,8
Also, both Cohorts 1 and 2 took place in general or subspecialty GI clinics (Cohort 3’s site types were not specified). However, the objective interpretation of tTG-IgA serology means it could be considered as an additional diagnostic tool for primary care physicians, as well.
Finally, if a primary care physician and their patient decide to go the “no-biopsy” route, it should be with a full discussion of the possible risks and benefits of not pursuing EGD. If there are any potential “red flag” symptoms suggesting the possibility of a more concerning differential diagnosis, EGD evaluation should still be pursued. Such symptoms might include (but not be limited to) chronic dyspepsia, dysphagia, weight loss, and unexplained anemia.7
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