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Case-finding strategy ineffective for clinical detection of celiac disease
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LAS VEGAS — Testing at-risk groups, or “case-finding,” is the current paradigm for clinical detection of celiac disease, but it may not be effective, according to research presented at ACG 2016.
“We found that people with undiagnosed celiac disease and people without have the same frequency of indications to clinically test for celiac disease,” Isabel A. Hujoel, MD, from the Mayo Clinic in Rochester, Minn., said during her presentation. “Therefore ... case finding may not be effective, as it failed to discriminate between those with undiagnosed celiac disease and those without, and it exposed a number of people without celiac disease to the harms associated with screening.”
Case-finding involves filtering a general population with a low pre-test probability of celiac disease to create a smaller tested population with a higher pre-test probability of celiac disease, Hujoel explained.
While studies suggest this strategy is effective, with a 32- to 43-fold increase in diagnosis in the primary care setting, others suggest the GI symptoms used as filters may not be predictive of positive celiac serology. Furthermore, the U.S. Preventive Services Task Force deemed the evidence supporting targeted testing for celiac disease inadequate earlier this year.
Therefore, Hujoel and colleagues sought to determine the frequency of clinical testing for celiac disease, and the frequency of indications for clinical testing in adults with and without celiac disease in their community.
They tested stored blood samples from 35,299 adults without a celiac diagnosis for tissue transglutaminase antibodies (tTGA), and further tested tTGA-positive or -equivocal samples for endomysial antibodies (EMA). Then they paired 400 EMA-positive samples, identified as undiagnosed celiac disease cases, with 400 age- and sex- matched tTGA negative samples as referents (61% women; median age, 44.2 years), and reviewed their electronic medical records.
Indications for testing included “classical symptoms such as chronic diarrhea and weight loss, nonclassical symptoms such as iron deficiency and elevated liver function tests, and associated conditions such as a family history of celiac disease or autoimmune conditions,” Hujoel said.
Overall, they found similar frequencies of any indication for clinical testing in undiagnosed celiac cases (40%) and referents (37%).
“This means we would ultimately test a population of 13,000 people in order to diagnose 159 cases of celiac disease,” Hujoel said, adding that the prevalence of celiac disease in the tested population (1.2%) is therefore very similar to the prevalence in the initial population (1.1%).
“Case-finding did not increase the pre-test probability of celiac disease in our tested population,” she said. “Additionally, we would have to test 12,900 people who do not have celiac disease and expose them to the harms associated with screening. Finally, of the cases of undiagnosed celiac disease, 60% would not have any indication to test and would remain undiagnosed if case-finding were to be applied perfectly.”
Likewise, there was no statistically significant difference in the frequency of most individual indications for clinical testing between groups, except for hypothyroidism, which was found more frequently in undiagnosed celiac disease cases, and dyspepsia and chronic diarrhea, which were found more frequently in referents.
Additionally, they found the frequency of clinical testing was generally low, although significantly higher in referents compared with undiagnosed celiac disease cases (6.5% vs. 2.3%; P = .005), which is likely driven by the higher frequency of dyspepsia and chronic diarrhea among referents, Hujoel said.
“The signs, symptoms and conditions that we previously associated with a higher risk for celiac disease may not actually indicate a higher risk, and therefore we need to find a new method of detecting celiac disease and identifying these people at high risk,” she concluded. – by Adam Leitenberger
Reference:
Hujoel IA, et al. Abstract #27. Presented at: American College of Gastroenterology Annual Scientific Meeting; Oct. 17-19, 2016; Las Vegas, NV.
Disclosures: The researchers report no relevant financial disclosures.