Bilateral Versus Unilateral Stenting for Malignant Hilar Obstruction: A Meta-Analysis

Abstract

Introduction: Malignant hilar biliary obstruction is a dreaded complication of various types of cancers including pancreatic cancer, cholangiocarcinoma, gallbladder carcinoma, and hepatocellular carcinoma. Palliative endoscopic biliary drainage plays an important role in resolving jaundice and cholangitis. The optimal stenting techniques remain to be definitely decided and the necessity to drain both liver lobes in hilar tumors remains uncertain. We report a meta-analysis of studies comparing unilateral versus bilateral stenting for malignant hilar biliary obstruction. Methods: We searched Pubmed, Medline, Embase, and Cochrane for controlled studies that compared unilateral versus bilateral stenting for malignant hilar biliary obstruction. Studies were excluded if they were non-controlled or included patients with non-malignant and non-hilar obstruction. Studies selection and data extraction were done by 2 reviewers. Disagreement was solved by a third reviewer. The quality for each included study was assessed by Consort system. Heterogeneity of the studies was analyzed by Cochran’s Q statistics. Mantel Haenszel relative risk and mean difference were calculated with random effect for outcomes with significant heterogeneity; for all others the fixed effect method was used. Results: Seven studies met the inclusion criteria with a total of 634 patients. After the initial placement of stents, there was no significant difference in the occlusion rate between unilateral and bilateral stenting (odds ratio [OR]: 1.47; confidence interval [CI]: 0.68-3.19). There was moderate heterogeneity among results reported in the studies but the clinical characteristics of the patients and the method of outcome assessment were similar and did not change our inferences. A sensitivity analysis that sorted studies based on the use of metal versus plastic stents found no statistically significant difference in the occlusion rate. Therapeutic failure, defined as the lack of resolution of symptoms post stenting, was noted in 17% with unilateral stenting compared to 22% with bilateral stenting without a statistically significant difference (OR: 0.63; CI: 0.31-1.28). Bilateral stenting was associated with higher incidence of post-stenting cholangitis 22% compared to unilateral stenting 12% (OR 0.52; 95% CI 0.28-0.96). There was no evidence of publication bias among the reported outcomes. Conclusion: When compared to bilateral stenting, unilateral stenting performed for patients with malignant hilar strictures is associated with lower incidence of post-stenting cholangitis, similar success in symptom resolution and no difference in the post stenting occlusion rate. Therefore, in the majority of patients with malignant biliary obstruction, unilateral stenting provides similar outcome to bilateral stenting.