Are Double-Layer Stents Better than Plastic Stents and Self-Expandable Metal Stents in Palliating Malignant Biliary Obstruction? Meta-Analysis and Systematic Review

Background: Double layer stents (DLS) were designed to overcome the limitations of plastic stents (PS) and self-expandable metal stents (SEMS) in palliating inoperable malignant biliary obstructions (MBO). Aims: Primary outcomes are stent patency period, occlusion rates and adverse events. Methods: Study Selection Criteria: Studies using DLS, SEMS and PS for palliation of patients with inoperable MBO. Data collection and extraction: Articles were searched in Pubmed and Ovid. Statistical method: Pooled proportions were calculated using both fixed and random effects model. Results: Initial search identified 374 reference articles, of which 41 were selected and reviewed. Five studies (N=460) for DLS, SEMS and PS which met the inclusion criteria were included in this analysis. Pooled analysis by fixed effects showed DLS patency to be 118.9 days (95% CI=110.4 to 127.4) compared to 77.4 days (95% CI=70.2 to 84.6) in PS and 170.7 days (95% CI=154.4 to 187.0) in SEMS. Stent occlusion rates in DLS, PS and SEMS group were 8.1% (95% CI=7.1 to 9.0), 37.5% (95% CI=33.8 to 41.1) and 19.9% (95% CI=18.1 to 21.7) respectively. Conclusions: In palliating inoperable MBO patients, DLS seem to be superior to PS. SEMS tend to have higher occlusion rates compared to DLS.