SAN DIEGO — Celiac disease affects an estimated 1% of people in the United States, yet only about 3% of people with the disease are being diagnosed, Dr. Peter H.R. Green said at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
Reasons for the poor rate of diagnosis are multifactorial, said Dr. Green, who directs Columbia University's Celiac Disease Center in New York. They include:
▸ A shift to the silent form of celiac disease. “The patients and the doctors are on the wrong pages in the [medical] textbooks,” he said. “The patients got it wrong in that they forgot to get diarrhea, and the doctors got it wrong in that they thought that all patients with celiac disease had to have diarrhea.” In fact, he explained, only about half of celiac disease patients present with diarrhea.
So-called silent modes of presentation include bone disease, weight loss, dermatitis herpetiformis, psoriasis, chronic urticaria, and anemia, including iron-deficiency anemia.
“There are increased rates of atopy and there are oral manifestations [in the form of] dental enamel defects such as yellow spots, white spots, and brown spots,” he added.
High-risk groups that Dr. Green screens include patients with a family history of celiac disease, patients with type 1 diabetes, and those with primary biliary sclerosis and Sjögren's syndrome.
▸ Physicians' failure to recognize celiac disease. Physicians “are taught that it's a rare condition,” he said, when in fact it is not and the clinical manifestations vary widely. “That's one of the reasons why there is such a low rate of diagnosis, because no one set of doctors [is] looking at all of those patients.”
▸ Lack of support from the pharmaceutical industry. “We know that over 80% of medical research is financed by the pharmaceutical industry, and by far the bulk of postgraduate education is financed by the pharmaceutical industry,” said Dr. Green, who is also a professor of medicine at Columbia.
The major sources of referrals to Columbia's Celiac Disease Center are neurologists. Other common sources of referral include gynecologists, endocrinologists, and rheumatologists.
In patients with suspected celiac disease, Dr. Green and his associates consider a panel of tests that include the tissue transglutaminase 2 (tTG)-IgA, the tTG-IgG, the IgA endomysial antibody (EMA), and total IgA level. “The best test is probably tTG-IgA, and throw in the tTG-IgG,” he said. “The IgA endomysial antibody need not be done routinely, but it's of value in difficult cases.”
The accepted standard for diagnosis is a biopsy of the descending duodenum. Most celiac disease patients (90%) will have a Marsh III lesion on biopsy, which includes partial, subtotal, and total villous atrophy.
Patients with celiac disease face a 10-fold increased risk of having at least one other autoimmune disease.
Various malignancies have also been linked to having celiac disease, including esophageal and head and neck squamous cell carcinoma, small intestinal carcinoma, and non-Hodgkin's lymphomas.
The management of celiac disease is a lifelong gluten-free diet, which Dr. Green said is difficult to follow in the United States. He recalled seeing gluten-free options on the menu at an ice cream store in Buenos Aires. In Argentina, he said, “there's a lot of celiac disease, and people have very good services.”
Dr. Green predicted that more people will be diagnosed with celiac disease as physicians learn about the wide variability of clinical presentation and the availability of sensitive and specific tests. “As more people become diagnosed, there will be greater awareness, and then people with celiac disease will get a better deal in this country.”
Physicians 'are taught that it's a rare condition,' when in fact it is not and the clinical manifestations vary widely. DR. GREEN