Abdullah Shatnawei, MD

Credit: Cleveland Clinic Abu Dhabi

A serological test can help identify patients who are at risk of developing celiac disease, according to new research.

A team, led by Abdullah Shatnawei, MD, Cleveland Clinic Abu Dhabi, characterized patients with celiac disease by examining the clinical spectrum of the disease and evaluated the performance of serologic tests for celiac disease screening in the United Arab Emirates (UAE).

Biopsies

Currently, duodenal biopsy is considered the gold standard for diagnosing celiac disease, using several serologic biomarkers, including anti-tissue transglutaminase (tTg) immunoglobulin (Ig)A test is included as an initial screening tool in the diagnostic algorithms of all recent guidelines.

In the study, the investigators reviewed medical charts from the Digestive Diseases Institute of Cleveland Clinic Abu Dhabi between 2015-2020.

Each participant was screened for anti-tissue transglutaminase IgA (Anti-tTG-IgA), anti-tissue transglutaminase IgG (Anti-TtG-IgG), anti-deamidated gliadin peptide IgG (Anti-DGP-IgG), and anti-deamidated gliadin peptide IgA (Anti-DGP-IgA).

The investigators performed histopathology on patients with seropositive tests and confirmed the diagnosis with a Marsh score greater than 1.

They then described characteristics of the Anti-tTG-IgA seropositive patients, which was correlated with histopathological confirmed celiac disease.

Overall, there were 6239 patients included in the study.

Results

The results show 1.4% were seropositive to Anti-tTG-IgG, while 2.9% were seropositive to Anti-TtG-IgA, 4.7% were seropositive to Anti-DGP-IgA, and 4.9% were seropositive to Anti-DGP-IgG.

After 300 patients were screened with a biopsy, 38.7% (1.9% of the total serologically screened) were confirmed with celiac disease.

The mean age of Anti-TtG-IgA seropositive patients was 32.1 ± 10.3 SD years, while 72% this group was female and 93.4% were Emirati.

In addition, 28.7% of this group was overweight and 24.7% were obese. On the other hand, only 5.8% of patients were considered underweight.

The results also show 46.7% of patients had anemia, while 21.3% had gastroesophageal reflux disease (GERD), 7.7%had autoimmune thyroid disease, 5.5% had type 1 diabetes, and 3.3% had type 2 diabetes.

For Anti-TtG IgA seropositive patients, 47.8% were deficient of vitamin D.

The results also show 10.3% (n = 12) of the patients with celiac disease that was histopathological confirmed were seronegative to Anti-TtG-IgA, but seropositive to anti-DGP-IgA and/or Anti-DGP-IgG. Body mass index, GERD, autoimmune thyroid disease, type 1 diabetes, asthma, hemoglobin, and vitamin D concentration were all correlated with biopsy-confirmed celiac disease (P <0.05).

Finally, Anti-TtG-IgA had the highest sensitivity at 89.7% and specificity at 83.7% compared to the gold-standard biopsy test.

“Three and two of every 100 patients were serologically (anti-tTG-IgA positive) and histopathological diagnosed with [celiac disease], respectively,” the authors wrote. “Although Anti-TtG-IgA is the most sensitive, specific, and commonly used test, one of every ten histopathological confirmed patients and Anti-tTG-IgA seronegative were seropositive to Anti-DGP. To avoid missing patients with [celiac disease], a comprehensive serological investigation covering DGP-IgG/IgA is warranted.”

References:

Shatnawei A, AlNababteh AH, Govender RD, Al-Shamsi S, AlJarrah A, Al-Rifai RH. Mode of presentation and performance of serology assays for diagnosing celiac disease: A single-center study in the United Arab Emirates. Front Nutr. 2023 Apr 5;10:1107017. doi: 10.3389/fnut.2023.1107017. PMID: 37090770; PMCID: PMC10113562.