Select adult patients with immunoglobulin A-tissue transglutaminase antibody levels (IgA-tTG) greater than or equal to 10 times the upper limit of normal (ULN) and a moderate-to-high pretest probability of celiac disease could be diagnosed without undergoing invasive endoscopy and duodenal biopsy, according to a new study.
Current international guidelines recommend duodenal biopsies to confirm a celiac disease diagnosis in adult patients, but growing evidence suggests invasive procedures may not be needed, the authors wrote.
"Our study confirms the high accuracy of serology-based diagnosis of coeliac disease in select adult patients," said Mohamed G. Shiha, MBBCh, MRCP, lead author and a clinical research fellow in gastroenterology at Sheffield Teaching Hospitals in the United Kingdom.
"This no-biopsy approach could lead to a shorter time to diagnosis, increased patient satisfaction, and reduced healthcare costs," he said.
The study was published online in Gastroenterology.
Evaluating the No-Biopsy Approach
Dr. Shiha and colleagues conducted a systematic review and meta-analysis to evaluate the accuracy of a no-biopsy approach for diagnosing celiac disease in adults. They looked for studies that reported the sensitivity and specificity of IgA-tTG ≥10xULN compared with duodenal biopsies (with a Marsh grade ≥ 2) in adults with suspected celiac disease.
The research team used a bivariate random-effects model to calculate the summary estimates of sensitivity, specificity, and positive and negative likelihood ratios. Then the positive and negative likelihood ratios were used to calculate the positive predictive value (PPV) of the no-biopsy approach across different pretest probabilities of celiac disease.
Among 18 studies with 12,103 participants from 15 countries, the pooled prevalence of biopsy-proven celiac disease was 62%. The proportion of patients with IgA-tTG ≥10xULN was 32%.
The summary sensitivity of IgA-tTG ≥10xULN was 51%, and the summary specificity was 100% for the diagnosis of celiac disease. The positive and negative likelihood ratios were 183.42 and.49, respectively. The area under the summary receiver operating characteristic curve was.83.
Overall, the PPV of IgA-tTG ≥10xULN to identify patients with celiac disease was 98%, which varied according to pretest probability of celiac disease in the studied population. Specifically, the PPV was 65%, 88%, 95%, and 99% if celiac disease prevalence was 1%, 4%, 10%, and 40%, respectively. The 40% prevalence represents the lower confidence interval of the pooled prevalence from the included studies, the authors noted.
"We provided PPV estimates of IgA-tTG ≥10xULN for common pretest probabilities of coeliac disease to aid clinicians and patients in reaching an informed decision on a no-biopsy diagnosis based on the best available evidence," the authors wrote.
Considering Additional Factors
Due to the increased accuracy of serological tests, pediatric guidelines have adopted a no-biopsy approach, the authors wrote. Children with IgA-tTG ≥10xULN and positive serum endomysial antibodies (EMA) can be diagnosed with celiac disease without biopsy.
However, the no-biopsy approach remains controversial for diagnosing adult patients and requires additional study, the authors wrote. They noted a limitation that all included studies were conducted in secondary and tertiary care settings and excluded patients with known celiac disease or on a gluten-free diet, so the results may not be generalizable to primary care settings.
In addition, relying on serology testing alone could lead to potential false-positive diagnoses, unnecessary dietary restriction, and negative effects on patients' quality of life, the authors wrote.
At the same time, duodenal biopsy may not always be accurate due to inadequate sampling and could result in false-negative histology. The no-biopsy approach could mitigate this potential risk, the authors noted.
"This study systematically collates the growing data supporting the accuracy of antibody testing to diagnose celiac disease," said Benjamin Lebwohl, MD, AGAF, professor of medicine and epidemiology at Columbia University Medical Center and director of clinical research for the Celiac Disease Center at Columbia University, New York. Dr. Lebwohl wasn't involved with this study.
"We have historically relied on duodenal biopsy to confirm the diagnosis of celiac disease, and the biopsy will still have a central role in most cases in the foreseeable future," he said. "But as we hone our understanding of antibody testing, one day we may be able to accept or even recommend a biopsy-free approach in select patients."
Two authors reported grant support from the National Institute for Health and Care Research and National Institute of Diabetes and Digestive and Kidney Diseases. Dr. Shiha reported speaker honorarium from Thermo Fisher. Dr. Lebwohl reported no relevant disclosures.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.