A Prospective Multicenter Study of a Fully Covered Metal Stent in Patients with Distal Malignant Biliary Obstruction: WATCH-2 Study.

BACKGROUND: Both fully covered (FC) and partially covered (PC) self-expandable metal stents (SEMSs) are now commercially available for distal malignant biliary obstruction (MBO). While FCSEMS can be easily removed at the time of re-interventions, it is theoretically prone to migration. However, few comparative data between FC and PC SEMSs have been reported.

AIMS: The aim of this study was to compare clinical outcomes of FCSEMS with those of PCSEMS.

METHODS: This was a multicenter, prospective study of FCSEMS for unresectable distal MBO with a historical control of PCSEMS, which was previously reported as the WATCH study. The primary outcome was recurrent biliary obstruction (RBO), and secondary outcomes were stent migration, stent removal, stent-related adverse events, and survival.

RESULTS: A total of 151 cases with unresectable distal MBO undergoing FCSEMS placement were enrolled and compared with a historical cohort of 141 cases undergoing PCSEMS placement. No significant differences were found in the rate of RBO (29 vs. 33%; P = 0.451), time to RBO (318 vs. 373 days; P = 0.382), and survival (229 vs. 196 days; P = 0.177) between FCSEMS and PCSEMS. The rate of stent migration also did not differ significantly between the two groups (14 vs. 8%; P = 0.113). The removal of FCSEMSs was successful in all 24 attempted cases (100%).

CONCLUSIONS: FCSEMSs appeared comparable to PCSEMSs in terms of RBO without a significant increase in stent migration rate in patients with unresectable distal MBO.

CLINICAL TRIAL REGISTRATION NUMBER: UMIN000007131.