501. CLINICAL APPLICATION OF OESOPHAGEAL CELL COLLECTION DEVICE AND BIOMARKER TESTING IN SYMPTOMATIC REFLUX DISEASE: A NATIONAL RETROSPECTIVE COHORT STUDY

Abstract Background Oesophageal cell collection device (OCCD) and biomarker testing was implemented nationally across Scotland in 2020 following the COVID-19 pandemic for symptomatic reflux patients referred to secondary care. Collected cells undergo biomarker testing for the presence of trefoil factor 3 (TFF3), an indicator of intestinal metaplasia (IM), in addition to atypia and p53. This national retrospective cohort study is the first to evaluate the clinical application of OCCD testing in symptomatic reflux patients and aims to assess whether OCCD and biomarker testing can safely be used as a triage tool for upper gastrointestinal (UGI) endoscopy in this cohort within secondary care. Methods Over a 32-month period, all patients undergoing OCCD testing with Cytosponge™ for investigation of reflux symptoms across 11 Scottish health boards were identified from prospectively maintained databases. In addition to OCCD testing, all patients also underwent clinical assessment either by UGI specialist nurses or consultants in secondary care. Individual patient records were interrogated to collect baseline demographics, OCCD test result and ongoing clinical management. Further analysis was performed on patients who subsequently underwent UGI endoscopy. All OCCD tests for Barrett’s surveillance were excluded from analysis. Results 1385 OCCD tests were performed for reflux symptoms in 1305 patients. 1103/1385 tests (79.6%) were TFF3 negative: 912/1305 (69.9%) patients discharged with no additional investigations. 355/1305 patients (27.2%) subsequently underwent UGI endoscopy. When insufficient tests with missing biomarker data were excluded, 50/314 patients (15.9%) had biopsies demonstrating IM: biomarkers were significantly more likely to be positive in this group (35.5% vs. 3.2%, p<0.001) (Table 1). 10/1103 patients with a TFF3 negative result (0.9%) had biopsies showing IM, dysplasia or malignancy. 1 patient had a TFF3 negative result but was diagnosed with oesophageal adenocarcinoma 27 months later. Conclusion OCCD and biomarker testing is effectively identifying those symptomatic reflux patients requiring further investigation with UGI endoscopy within the real-world setting. Biomarker testing is clearly aiding the diagnosis of Barrett’s oesophagus within this patient cohort. However, clinical assessment remains crucial to identify those with red flag symptoms and judicious follow-up of the discharged group will be critical to validate the ongoing use of OCCD testing in the long-term.