Serum testing may simplify diagnostic criteria, avoid biopsy in suspected celiac disease
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Key takeaways:
- The positive predictive value of serum anti-tissue transglutaminase IgA was 93.9%.
- Serum levels of 10 times the upper limit of normal may safely establish an accurate diagnosis of celiac disease without biopsy.
High levels of serum anti-tissue transglutaminase IgA predicted duodenal villous atrophy and could be a reliable measure to avoid biopsy in the diagnosis of adult patients with suspected celiac disease, according to researchers.
“Celiac disease (CeD) is increasing in prevalence and incidence around the world,” Carolina Ciacci, MD, of the Center for Celiac Disease at the University of Salerno in Italy, told Healio. “The traditional diagnosis of CeD is based on specific serology plus intestinal biopsy. Accuracy of gluten-specific serology is very high in predicting CeD diagnosis, while histology requires upper endoscopy and remains operator-dependent.
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“Previous investigations in children and adults supported the contention that a biopsy can be avoided in many patients with CeD with positive serology.”
In a multicenter prospective study, Ciacci and colleagues assessed the accuracy of serum anti-tissue transglutaminase IgA (tTG-IgA) as a non-biopsy strategy to diagnose celiac disease among 436 adults (mean age, 40 years; 68% women) with suspected disease who were not deficient in IgA. Diagnosis was defined by duodenal villous atrophy.
According to results published in The Lancet Gastroenterology & Hepatology, researchers detected positive serum tTG-IgA in 83% of participants and negative tTG-IgA in 17%. Of the 363 individuals with positive results, 341 had positive histology, or true positives, and 22 had negative histology, or false positives, following local review. Of the 73 participants with negative tTG-IgA results, seven had positive histology and 66 had negative histology.
The positive predictive value of serum testing was 93.9% (95% CI, 89.2-98.6), while the negative predictive value was 90.4% (95% CI, 85.5-95.3). Sensitivity and specificity were 98% (95% CI, 95.3-100) and 75% (95% CI, 66.6-83.4), respectively.
“High levels of tTG-IgA predict intestinal damage and allow omitting the biopsy in diagnosing CeD in adult patients with high pretest probability,” Ciacci said. “Serum levels of tTG-IgA of 10 times the upper limit of normal may safely establish an accurate diagnosis of CeD without endoscopy and duodenal biopsy.”
Using local data on histology and serology, researchers also reported that the area under the curve for serum tTG-IgA for prediction of duodenal villous atrophy was 0.87 (95% CI, 0.81-0.92) and 0.93 (95% CI, 0.89-0.96) when applying categorical and numerical definitions of serum tTG-IgA, respectively.
“The practical clinical implication of this study is the potential simplification of the diagnostic algorithm for the workup of adult patients with a high pretest probability of CeD,” Ciacci told Healio. “The exclusion of the duodenal biopsy and histology requirement may result in a highly significant saving of time, cost, risk and patient burden.”
She continued: “Although the accuracy of anti-tTG-IgA antibodies test was excellent in all international centers, there is a need to standardize the test and fix the range of normality. Moreover, the no-bio strategy, at the moment, should be utilized by centers with high familiarity with CeD and its consequences.”
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