Comparative Effectiveness of Biliary Brushings and Biopsies in the Diagnosis of Malignant Biliary Strictures: A Systematic Review and Meta-Analysis

Abstract

Introduction: Evaluation of indeterminate biliary strictures typically involves collection and analysis of tissue or cells. Brush cytology and intraductal biopsies which are routinely performed at ERCP to assess malignant-appearing biliary strictures are limited by relatively low sensitivity. Our aim was to study the comparative effectiveness of brushings and biopsies in the etiology of biliary strictures. Methods: In this meta-analysis, Pubmed and Embase databases were reviewed for studies published to April 2014 where diagnostic correlation of histology was available. Studies only reporting ‘positive for malignancy’ were included in our analysis. As there were no false positives in our included studies we performed meta-analysis of only sensitivities by removing the logit specificity and correlation parameters from the standard bivariate model thus simplifying the model to a univariate random-effects logistic regression model. The negative likelihood ratio was derived from the model by using the estimated summary sensitivity and assuming a specificity of 1. Results: The search yielded 9 studies involving 703 patients. The overall pooled sensitivity and negative likelihood ratio of brushings for the diagnosis of malignant biliary strictures was 44.5% [95% confidence interval (CI): 39.5%-49.6%] and 0.56 (95% CI: 0.50-0.61), respectively. The overall pooled sensitivity and negative likelihood ratio of biliary biopsies for the diagnosis of malignant biliary strictures was 49.7% [95% (CI): 44.3%-55.1%] and 0.50 (95% CI: 0.45-0.56), respectively (Figure 1).Figure 1: Forest plot demonstrating the sensitivity and specificity of brushings and biopsies in the diagnosis of malignant biliary strictures.Conclusion: Our study suggests that both brushings and biopsy are comparable for the diagnosis of malignant biliary strictures. However, both modalities have limited sensitivity in the diagnosis of malignant biliary strictures.