Antireflux covered metal stent for nonresectable distal malignant biliary obstruction: Multicenter randomized controlled trial

Background and Aim: An antireflux metal stent (ARMS) for nonresectable distal malignant biliary obstruction (MBO) may prevent recurrent biliary obstruction (RBO) as a result of duodenobiliary reflux and prolong time to RBO (TRBO). Superiority of ARMS over conventional covered self-expandable metal stents (SEMS) has not been fully examined. Methods: We conducted a multicenter randomized controlled trial to examine whether TRBO of an ARMS with a funnel-shaped valve was longer than that of a covered SEMS in SEMS-naïve patients. We enrolled 104 patients (52 patients per arm) at 11 hospitals in Japan. Secondary outcomes included causes of RBO, adverse events, and patient survival. Results: TRBO did not differ significantly between the ARMS and covered SEMS groups (median, 251 vs 351 days, respectively; P=0.11). RBO as a result of biliary sludge or food impaction was observed in 13% and 9.8% of patients who received an ARMS and covered SEMS, respectively (P=0.83). ARMS was associated with a higher rate of stent migration compared with the covered SEMS (31% vs 12%, P=0.038). Overall rates of adverse events were 20% and 18% in the ARMS and covered SEMS groups, respectively (P=0.97). No significant between-group difference in patient survival was observed (P=0.26). Conclusions: The current ARMS was not associated with longer TRBO compared with the covered SEMS. Modifications including addition of an anti-migration system are required to use the current ARMS as first-line palliative treatment of distal MBO (UMIN-CTR clinical trial registration number: UMIN000014784).