Comparative effectiveness of biliary brush cytology and intraductal biopsy for detection of malignant biliary strictures: a systematic review and meta-analysis

Background: Evaluation of indeterminate biliary strictures typically involves collection and analysis of tissue or cells. Brush cytology and intraductal biopsies that are routinely performed during ERCP to assess malignant-appearing biliary strictures are limited by relatively low sensitivity. Objective: To study the comparative effectiveness of brushings for cytology and intraductal biopsies in the etiology of biliary strictures. Design: Meta-analysis. Setting: Referral center. Patients: PUBMED and Embase databases were reviewed for studies published to April 2014 where diagnostic correlation of histology was available. Intervention: Database and review of study findings. Main Outcome Measurements: Sensitivity and specificity. Results: The pooled sensitivity and specificity of brushings for the diagnosis of malignant biliary strictures was 45% (95% confidence interval [CI], 40%-50%) and 99% (95% CI, 98%-100%), respectively. The pooled diagnostic odds ratio to detect malignant biliary strictures was 33.43 (95% CI, 14.29-78.24). For intraductal biopsies, the pooled sensitivity and specificity were 48.1% (95% CI, 42.8%-53.4%) and 99.2% (95% CI, 97.6%-99.8%), respectively. The pooled diagnostic odds ratio to detect malignant biliary strictures was 43.18 (95% CI, 19.39-95.83). A combination of both modalities only modestly increased the sensitivity (59.4%; 95% CI, 53.7%-64.8%) with a specificity of 100% (95% CI, 98.8%-100.0%). The Begg-Mazumdar and Egger tests indicated a low potential for publication bias. Limitations: Inclusion of low-quality studies. Conclusion: Our study suggests that both brushings and biopsy are comparable and have limited sensitivity for the diagnosis of malignant biliary strictures. A combination of both only modestly increases the sensitivity.