AIM:To compare efficacy and complications of par-tially covered self-expandable metal stent(pcSEMS)to plastic stent(PS)in patients treated for malignant,infrahilar biliary obstruction.METHODS:Multicenter prospective randomized clinical trial with treatment allocation to a pcWallstent(SEMS)or a 10 French PS.Palliative patients aged≥18,for infrahilar malignant biliary obstruction and a Karnofsky performance scale index>60%from 6 participating North American university centers.Primary endpoint was time to stent failure,with secondary outcomes of death,adverse events,Karnofsky performance score and short-form-36 scale administered on a three-monthly basis for up to 2 years.Survival analyses were performed for stent failure and death,with Cox proportional hazards regression models to determine significant predictive characteristics.RESULTS:Eighty-five patients were accrued over 37mo,42 were randomized to the SEMS group and 83patients were available for analyses.Time to stent failure was 385.3±52.5 d in the SEMS and 153.3±19.8 d in the PS group,P=0.006.Time to death did not differ between groups(192.3±23.4 d for SEMS vs211.5±28.0 d for PS,P=0.70).The only significant predictor was treatment allocation,relating to the time to stent failure(P=0.01).Amongst other measured outcomes,only cholangitis differed,being more common in the PS group(4.9%vs 24.5%,P=0.029).The small number of patients in follow-up limits longitudinal assessments of performance and quality of life.From an initially planned 120 patients,only 85 patients were recruited.CONCLUSION:Partially covered SEMS result in a longer duration till stent failure without increased complication rates,yet without accompanying measurable benefits in survival,performance,or quality of life. AIM: To compare efficacy and complications of par-tially covered self-expandable metal stent (pcSEMS) to plastic stent (PS) in patients treated for malignant, infrahilar biliary obstruction. METHODS: Multicenter prospective randomized clinical trial with treatment allocation to a pc Wallstent SEMS) or a 10 French PS. Prophetic planors aged> 18, for infrahilar malignant biliary obstruction and a Karnofsky performance scale index> 60% from 6 participating North American university centers. Primary endpoint was time to stent failure, with secondary outcomes of death, adverse events, Karnofsky performance score and short-form-36 scale administered on a three-monthly basis for up to 2 years. Survival analyzes were performed for stent failure and death, with Cox proportional hazards regression models to determine significant predictive characteristics .RESULTS: Eighty-five patients were accrued over 37mo, 42 were randomized to the SEMS group and 83patients were available for analyzes. Time to stent failure was 3 85.3 ± 52.5 d in the SEMS and 153.3 ± 19.8 d in the PS group, P = 0.006. Time to death did not differ between groups (192.3 ± 23.4 d for SEMS vs 211.5 ± 28.0 d for PS, P = 0.70). The only significant predictor was treatment allocation, relating to the time to stent failure (P = 0.01). Amongst other measured outcomes, only cholangitis differed, being more common in the PS group (4.9% vs 24.5%, P = 0.029). small number of patients in follow-up limits longitudinal assessments of performance and quality of life. Fund anterior plan 120 patients, only 85 patients were recruited. CONCLUSION: Partially covered SEMS result in a longer duration to stent failure without increased complication rates, yet without accompanying measurable benefits in survival, performance, or quality of life.