No-Biopsy Diagnosis of CD an Option in 'Carefully Selected' Adult Patients

By Anne Harding

November 30, 2020

NEW YORK (Reuters Health) - No-biopsy diagnosis of celiac disease (CD) is possible in both adults and children, although the sensitivity is low, new findings suggest.

Across three adult cohorts, nearly everyone with IgA antitissue transglutaminase (tTG) antibody levels at least 10-fold higher than the upper limit of normal (ULN) had injuries to the small intestine characteristic of CD, Dr. David S. Sanders of Royal Hallamshire Hospital in Sheffield, U.K., and colleagues report in Gut.

"This is a paradigm shift in the diagnosis of patients with celiac disease," Dr. Sanders told Reuters Health by phone. "We think it will reduce the number of endoscopies by about 25% for this group of patients, maybe more."

According to guidelines from the European Society for the Study of Paediatric Gastroenterology, Hepatology and Nutrition, an IgA tTG titer higher than 10 times the ULN and a positive test for antiendomysial IgA antibodies (EMA) are adequate to support a CD diagnosis in pediatric patients. Studies suggest that this approach could also predict CD in adults, the authors note, but it has not been widely adopted.

To investigate the predictive capacity and diagnostic yield of 10-fold increased IgA tTG antibodies for CD in adults, the researchers looked at three cohorts: 740 patients treated at a specialist CD clinic (cohort 1), 532 referred for upper gastrointestinal (GI) endoscopy with a low suspicion for CD (cohort 2), and 145 patients with high tTG from several sites (cohort 3).

In cohort 1, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 10-fold elevated IgA tTG antibodies for identifying individuals with Marsh 3 histology were 54%, 90%, 99% and 13%.

For cohort 2, the corresponding estimates were 50%, 100%, 100% and 98%, respectively, and for cohort 3, 30%, 83%, 95% and 10%.

Dr. Sanders said patients at his center are being offered the no-biopsy option. He emphasized that it is essential for institutions to validate their tTG test kits. "Every hospital and medical center will need to be sure of their kit," he said.

Also, he advised physicians who suspect CD in their patients to consult a gastroenterologist before suggesting dietary modifications.

"The most important thing is for doctors to carefully discuss this with their patients," Dr. Sanders said. "Once you're on a gluten-free diet it's very hard to try and go back and get a diagnosis."

SOURCE: https://bit.ly/3fyVMfk Gut, online November 2, 2020.

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