Determination of a Treatment Response Threshold for the Eosinophilic Esophagitis Endoscopic Reference Score.

Background and study aims: While endoscopic features of eosinophilic esophagitis (EoE) are measured using the validated EoE Endoscopic Reference Score (EREFS), a threshold for treatment response has not been defined. We aimed to determine a cut-point for endoscopic response as measured by EREFS. Patients and Methods: We performed a secondary analysis of a randomized clinical trial comparing budesonide slurry to swallowed fluticasone multidose inhaler for initial treatment of EoE. In the parent trial, EREFS was determined before and after treatment (score range 0-9), as were histologic findings and dysphagia symptoms. We performed tabular, flexible trend, and dependent mixture analyses of measures of treatment response to select the best clinical EREFS threshold. Results: In the 111 included subjects (mean age 39 years; 67% male; 96% white), an EREFS threshold of ≤2 was 80% sensitive (95% confidence limits 69 - 88%) and 83% specific (95% confidence limits 67 - 94%) for histologic response (peak of 75% at EREFS of 2 or 3. Conclusions: An EREFS of ≤2 was the best clinical threshold for endoscopic response to topical steroid treatment and was consistent with clinical and histologic response. Therefore, future studies can report a binary outcome of endoscopic response when EREFS is two or less.