A recent study (SJ Ackerman et al. American Journal of Gastroenterology: October 2019 – Volume 114 – Issue 10 – p 1614–1625) provides additional data supporting the ‘string’ test to determine whether eosinophilic esophagitis is active or inactive. Thanks to Ben Gold for sharing this reference.
My take: The string test could be a useful test for monitoring response to treatment, especially if it could garner insurance coverage. When/if will it ever become available clinically? (prior publication as early as 2012: String test for EoE)
Here’s the link to the full-text open-access article: One-Hour Esophageal String Test: A Nonendoscopic Minimally Invasive Test That Accurately Detects Disease Activity in Eosinophilic Esophagitis
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 5 62), inactive EoE (n 5 37), and patient controls with a normal esophagus (n 5 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. Eightyseven 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.