October 12, 2026
3 min read
Key takeaways:
- The outpatient procedure can be performed without an endoscopist.
- There were no adverse events among the 22 adults who received 42 tests.
- Testing can be used to assess ongoing treatment, not establish diagnoses.
The esophageal string test was successful in assessing treatment among adults with eosinophilic esophagitis with no adverse events recorded, according to a study published in Annals of Allergy, Asthma & Immunology.
Current assessments require invasive esophagogastroduodenoscopies (EGDs) performed up to every 8 to 12 weeks, Fouad Moawad, MD, chief of gastroenterology and professor of medicine, Scripps Clinic, and colleagues wrote.
Data derived from Lu J, et al. Ann Allergy Asthma Immunol. 2026;doi:10.1016/j.anai.2026.09.724.
“EGD with biopsy remains the standard for diagnosing EoE, assessing endoscopic features and, importantly, monitoring response to treatment. However, EGDs are invasive, typically require sedation, and can be burdensome for some patients,” Moawad told Healio.
“This burden can be particularly significant for patients using dietary therapy, where disease activity is reassessed as foods are eliminated and reintroduced,” he continued. “Because EoE is a chronic disease, patients may undergo many endoscopies over their lifetime.”
During the esophageal string test (EST), patients swallow a small capsule that is attached to the end of a string. The capsule collects samples while it is in the esophagus. Patients do not need sedation during the hour-long outpatient procedure, which also does not require an endoscopist.
“Patients fast from solid food for at least 2 hours and avoid beverages other than water for at least 1 hour before the test,” Moawad said.
Once the string is removed and the esophageal segment is identified, it is sent to a laboratory for analysis.
“While EST has limitations and does not replace endoscopy in every setting, our findings suggest it is a reasonable, minimally invasive alternative for monitoring disease activity in selected patients with established EoE,” Moawad said.
“Importantly, EST does not provide the endoscopic visualization or biopsies obtained with EGD, so it should be viewed as an alternative for monitoring selected patients rather than a replacement for endoscopy,” he added.
The retrospective analysis included 22 adults aged 18 to 75 years (mean age, 40 years) who completed 42 ESTs in a real-world allergy clinic between February 2024 and April 2026 with no vomiting, choking or other adverse effects. One patient had six EST procedures.
Patients were being treated via food elimination diets, proton pump inhibitors or dupilumab or receiving no treatment at all.
“Most published experience with EST has been in pediatric patients, so adult data remain limited,” Moawad said. “Every patient completed the test, and no adverse events were observed.”
Initial EST results included 10 patients (45.5%) with active disease based on the EST EoEScore. Six of them had at least one more EST, and four of these patients escalated therapy, with their disease then classified.
Among the 12 patients (54.5%) with inactive disease based on the initial EST, six had at least one more EST. Three of these patients, who also had been on food elimination diets, introduced food back into their diet and were classified with inactive disease via EST.
Clinicians recommended EGDs for all 22 patients after the EST, but 14 (63.6%) could not because they had poor symptom control. Three of these patients had active disease even though their symptoms had improved, based on EST.
Seven patients had nine ESTs within 4 weeks of an EGD with no change in treatment, with a mean duration of 9.6 days between the EST and EGD. The researchers called the results of seven of these ESTs (77.8%) concordant with the results of the EGDs.
“Just as importantly, the test was not simply providing information. It was being used to make clinical decisions,” Moawad said. “Results helped clinicians escalate therapy when disease remained active and, in other patients, guide food reintroduction after testing showed inactive disease.”
Approved for patients aged 7 years and older, ESTs are preferrable over EGD for children, their parents and adults when both assessments are available, the researchers said. Also, they said, their sensitivity is 72%, and their specificity is 89%.
“This demonstrates the potential for EST to become a practical tool for monitoring disease activity and guiding clinical management,” he said.
Moawad called training and implementation “relatively straightforward” as well, since outpatient clinics can provide testing without sedation.
“But clinicians also need to consider appropriate patient selection,” he said. “Our study evaluated adults with established EoE, and EST is best suited as a tool for monitoring disease activity rather than establishing the initial diagnosis.”
Also, the researchers said, ESTs could enable better access to assessments while reducing their burdens and costs, although they added that larger prospective studies are needed to examine how well they compare with EGDs.
“Our sample was small, and only a subset of patients had both tests performed within a short interval without a change in treatment. Ideally, EST would be performed at the time of endoscopy to allow a direct comparison between the two methods,” Moawad said.
“This would help us better define how reliably EST can be used to monitor disease activity and potentially reduce the need for repeated endoscopies in patients with EoE,” he said.
For more information:
Fouad Moawad, MD, can be reached at neurology@healio.com.
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