OBJECTIVES:Eosinophilic esophagitis (EoE), a chronic food allergic disease, lacks sensitive and specific peripheral biomarkers. We hypothesized that levels of EoE-related biomarkers captured using a 1-hour minimally invasive Esophageal String Test (EST) would correlate with mucosal eosinophil counts and tissue concentrations of these same biomarkers. We aimed to determine whether a 1-hour EST accurately distinguishes active from inactive EoE or a normal esophagus.METHODS:In a prospective, multisite study, children and adults (ages 7–55 years) undergoing a clinically indicated esophagogastroduodenoscopy performed an EST with an esophageal dwell time of 1 hour. Subjects were divided into 3 groups: active EoE, inactive EoE, and normal esophageal mucosa. Eosinophil-associated protein levels were compared between EST effluents and esophageal biopsy extracts. Statistical modeling was performed to select biomarkers that best correlated with and predicted eosinophilic inflammation.RESULTS:One hundred thirty-four subjects (74 children, 60 adults) with active EoE (n = 62), inactive EoE (n = 37), and patient controls with a normal esophagus (n = 35) completed the study. EST-captured eosinophil-associated biomarkers correlated significantly with peak eosinophils/high-power field, endoscopic visual scoring, and the same proteins extracted from mucosal biopsies. Statistical modeling, using combined eotaxin-3 and major basic protein-1 concentrations, led to the development of EoE scores that distinguished subjects with active EoE from inactive EoE or normal esophagi. Eighty-seven percent of children, 95% of parents, and 92% of adults preferred the EST over endoscopy if it provided similar information.DISCUSSION:The 1-hour EST accurately distinguishes active from inactive EoE in children and adults and may facilitate monitoring of disease activity in a safe and minimally invasive fashion.

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RATIONALE: Eosinophilic esophagitis (EoE), a chronic allergic disease, lacks sensitive and specific peripheral biomarkers. We hypothesized that concentrations of EoE-related biomarkers captured using a 1-hour minimally invasive Esophageal String Test (EST) would correlate with mucosal eosinophil counts and tissueconcentrations of the same biomarkers. We aimed to determine if a 1-hour EST accurately distinguishes active from inactive EoE. METHODS: In a prospective, multi-site study, children and adults (ages 7-55yrs) undergoing a clinically indicated esophagogastroduodenoscopy performed an EST with an esophageal dwell time of 1-hour. Subjects were divided into 4 groups: 1) active EoE, 2) inactive (treated) EoE, 3) GERD and 4) normal esophageal mucosa. Eosinophil-associated proteins were compared between EST effluents and esophageal biopsy extracts. Statistical modeling was performed to select biomarkers that best correlated with eosinophilic inflammation. RESULTS: 143 subjects (96 children, 47 adults) with active EoE (n562), inactive EoE (n537), GERD (n59) and normal esophagus (n535) completed the study; no serious adverse events were recorded. ESTcaptured eosinophil-associated proteins were significantly correlated with peak eosinophils/HPF, endoscopic visual scoring (EREFS), and the same proteins extracted from mucosal biopsies. Statistical modeling, using combined eotaxin-3 and MBP-1 concentrations, led to the development of EoE scores that distinguished between subjects with active EoE compared to inactive EoE in subjects with an EoE diagnosis, and compared to subjects with inactive EoE, GERD or normal esophagi. CONCLUSIONS: The 1-hour EST can be used to accurately distinguish active from inactive disease in children and adults with EoE and facilitate monitoring of EoE disease activity in a safe, minimally invasive fashion.