Esophageal string test shows promise for noninvasive eosinophilic esophagitis monitoring

A study published in Annals of Allergy, Asthma & Immunology demonstrates that the esophageal string test offers a safe, minimally invasive outpatient alternative to endoscopy for monitoring adults with established eosinophilic esophagitis. Led by Dr. Fouad Moawad, researchers analyzed 42 tests across 22 adults, reporting zero adverse events and a 77.8% concordance rate with traditional endoscopies.

Esophageal string test safety

• ▪A retrospective study in Annals of Allergy, Asthma & Immunology reported zero adverse events, choking, or vomiting among 22 adults completing 42 esophageal string tests between February 2024 and April 2026.
• ▪Every adult patient enrolled in the retrospective study successfully completed the esophageal string test.

Adult study participants

• ▪The 22 adult patients in the Scripps Clinic esophageal string test study ranged from 18 to 75 years old, had a mean age of 40, and were treated with diets, proton pump inhibitors, dupilumab, or no treatment.
• ▪Clinicians recommended esophagogastroduodenoscopies for all 22 study patients following string testing, but 14 could not undergo them due to poor symptom control.

Esophageal string test procedure and preparation

• ▪Patients taking the esophageal string test must fast from solid food for at least 2 hours and avoid beverages other than water for at least 1 hour before the procedure.
• ▪During the hour-long esophageal string test, patients swallow a small capsule attached to a string that collects esophageal samples without requiring sedation or an endoscopist.

Study findings on string test concordance and accuracy

• ▪Seven patients underwent nine esophageal string tests within 4 weeks of an esophagogastroduodenoscopy without treatment changes, yielding a 77.8% concordance rate between the two testing methods.
• ▪The esophageal string test demonstrates a sensitivity of 72% and a specificity of 89% for assessing disease activity in patients with eosinophilic esophagitis.

Clinical outcomes and management guided by string tests

• ▪Initial esophageal string tests identified active eosinophilic esophagitis in 10 patients, prompting clinicians to escalate therapy for four patients who underwent subsequent string testing.
• ▪Among 12 patients shown to have inactive disease on initial esophageal string tests, three guided by testing successfully reintroduced foods into their food elimination diets while maintaining inactive disease.

Role and future research of the esophageal string test

• ▪Lead researcher Dr. Fouad Moawad stated that larger prospective studies performing string tests simultaneously with endoscopies are needed to directly compare efficacy and refine monitoring protocols.
• ▪The researchers emphasized that the esophageal string test is designed for disease activity monitoring in patients with established eosinophilic esophagitis, not for initial diagnosis.

Standard diagnostic and monitoring procedures

• ▪Standard monitoring for eosinophilic esophagitis requires esophagogastroduodenoscopies with biopsies typically repeated every 8 to 12 weeks, which can be burdensome and usually require sedation.
• ▪Esophagogastroduodenoscopy with biopsy remains the medical standard for diagnosing eosinophilic esophagitis, assessing endoscopic features, and monitoring treatment response.