The 1-Hour Esophageal String Test: A Non-Endoscopic Minimally Invasive Test to Accurately Detect Disease Activity in Eosinophilic Esophagitis

Abstract

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.

Orodispersible budesonide tablets for the treatment of eosinophilic esophagitis: a review of the latest evidence

“…In the future some less-invasive tools – for example, the esophageal string test or the esophageal cytosponge – might help to solve this problem. 52,53 However, more work must be done in order to determine the role of these tools in the long-term monitoring of EoE.…”

Advancing patient care through the Consortium of Eosinophilic Gastrointestinal Disease Researchers (CEGIR)

“…Examples of these include mucosal impedance probes for measuring reflux, the string test for detecting intestinal parasites, the Cytosponge (Medtronic, Minneapolis, Minn) for detecting Barrett esophagus, confocal microscopy, endoscopic functional luminal imaging probe (endoFLIP) for detecting distensibility, transnasal endoscopy, and others, which have now all been repurposed for use in tracking EoE activity and understanding the pathogenesis of EoE. [64][65][66][67][68][69]…”

EoE disease monitoring

“…A small metal ball keeps the string in place in the patient's stomach. When the string is removed after an hour, 34 it can be analyzed to detect eosinophil-derived proteins. Current data suggest that the EST is a sensitive tool for detecting esophageal eosinophilia.…”