Acetylsalicylic acid for metal stent in malignant distal common bile duct obstruction: A randomized controlled trial

Background: Endoscopic biliary drainage is the treatment of choice for patients with malignant distal common bile duct obstruction. Self-expandable metal stents have clinical advantages including an increased duration of patency that may be prolonged by acetylsalicylic acid (ASA) use. The aim of this study was to investigate whether ASA had a positive effect on the patency of self-expandable metal stents compared with placebo. Methods: This prospective, multicenter, double-blinded, and randomized placebo-controlled trial was conducted from October 2017 to May 2020 in Korea. Patients who underwent palliative endoscopic biliary drainage with self-expandable metal stents for malignant distal bile duct obstruction were enrolled, and allocated to ASA treatment or placebo. The study outcomes were the rate of stent dysfunction at 6 months, duration of stent patency, risk factors for stent dysfunction, and any adverse events. Results: Interim analysis included 24 and 28 patients in the ASA and placebo groups, respectively. There was no significant difference between the ASA and placebo groups in stent dysfunction (25.0% vs. 20.7%, P = 0.761) or the duration of stent patency (150.97 ± 10.55 vs. 158.07 ± 8.70 days, P = 0.497). Six patients experienced suspected ASA-related adverse events, and there was one lethal case. Conclusions: ASA did not prolong stent patency. This study was terminated early because of the possibility of serious adverse events related to ASA treatment of these patients receiving palliative care.