S3235 Comparison of ERCP-Guided Biliary Brush Conventional Cytology and Liquid-Based Cytology in Diagnosing Malignant Biliary Strictures: A Systematic Review and Meta-Analysis

INTRODUCTION: Endoscopic retrograde cholangiopancreatography (ERCP) guided endobiliary brush cytology has been employed as a tool to diagnose malignant biliary strictures. Conventional cytology (CC) is limited by its moderate sensitivity. A new staining method compared to CC is liquid-based cytology (LBC). Commonly used LBC preparation techniques include filtration-based (ThinPrep®, CellPrep®) and precipitation-based (SurePathTM). The aim of this study was to conduct a systematic review and meta-analysis to evaluate the diagnostic efficacy of LBC compared to CC in diagnosing malignant biliary strictures. METHODS: We conducted a comprehensive search of several databases and conference proceedings including PubMed, EMBASE, Google-Scholar, MEDLINE, SCOPUS, and Web of Science databases (earliest inception to May 2020) to identify studies comparing LBC to CC in the diagnosis of malignant biliary strictures. The primary outcome was to calculate diagnostic efficacy of LBC compared to CC and the secondary outcome was to calculate pooled rates of sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of LBC compared to CC. The meta-analysis was performed using Der Simonian and Laird random effect model. RESULTS: Nine studies with a total of 870 patients of which 516 were in the LBC group and 354 were in the CC group (reported in 7/9 studies) were included in our analysis. Pooled sensitivity of LBC and CC was 69.7% (58.1-81.2) and 62.09% (47.42-76.77), specificity was 98.75% (97.25-100.00) and 99.17% (98.13- 100.00), PPV was 99% (99-100) for both and NPV was 47% (23.1-71.7) and 54% (32-76.55), respectively. CONCLUSION: In conclusion, LBC of biliary brush specimens has a higher sensitivity and comparable specificity, PPV and NPV as compared to CC. Although the current data is encouraging more randomized control trials are necessary.