NEW YORK — Serology tests for suspected celiac disease are often inappropriately ordered or managed, increasing the chance of missed diagnosis, according to a study presented at an international symposium on celiac disease.
An analysis of 349 positive antiendomysial antibody (EMA) tests over a 17-month period showed that 51% of patients had not received a concurrent serum IgA test to evaluate for IgA deficiency, and 10% of patients were overlooked for a follow-up intestinal biopsy, reported Kelly McGowan of the University of Calgary (Alta.).
IgA deficiency is more common in patients with celiac disease than in the general population, and its presence negates the results of EMA tests, according to Ms. McGowan. “The EMA tests were inappropriately ordered in the absence of IgA tests, because if a patient with IgA deficiency undergoes screening for celiac disease, their test result will always be negative.”
Of the positive serology tests, 69% were appropriately managed with a follow-up intestinal biopsy. A total of 194 biopsies were diagnostic of celiac disease, yielding a positive predictive value of 91% and a disease prevalence of 2%, based on the total sample of 9,533 patients tested.
Another 8% of positive serology tests did not include a follow-up biopsy but were considered to be appropriately managed because a biopsy had been done previously or was contraindicated, she said.
A further 3% of patients refused a biopsy, and 5% of tests were not followed up because of an administrative error.
But 10% of tests were classified as inappropriately managed because physicians failed to order a biopsy. For another 5% of tests, the physicians did not respond to the investigator's query about why they did not order a biopsy, possibly representing more mismanaged tests, she said.