Clinical outcomes of nitinol and stainless steel uncovered metal stents for malignant biliary strictures: is there a difference?

BackgroundSelf-expandable metal stents (SEMSs) made from nitinol (N) were developed as a potentially more effective alternative to conventional stainless steel (SS) stents.ObjectiveTo compare clinical outcomes of N versus SS stents in the management of malignant biliary strictures.DesignRetrospective study.SettingTertiary-care cancer center.PatientsAll patients with first-time N (Flexxus) and SS (Wallstent) uncovered biliary SEMSs placed between January 2006 and October 2007.InterventionsSEMS placement.ResultsA total of 81 N and 96 SS stents were placed. The most common cancer diagnosis was pancreatic (80.2% N; 62.5% SS; P = .06). The most frequent site of stricture was the common bile duct (85.2% N; 86.5% SS; P = .31). Biliary decompression was achieved in 93.8% of the N group and 86.4% of the SS group (P = .22). Immediate stent manipulation was required in 4 patients in each group. Subsequent intervention for poor drainage was performed in 17 N (21%) and 26 SS (27%) stents at mean times of 142.1 days (range, 5-541 days; median, 77 days) and 148.1 days (range, 14-375; median, 158.5), respectively (P = .17). The occlusion rate between N and SS stents was not significant (P = .42). The overall durations of stent patency in the N and SS group were similar (median 129 and 137 days, respectively; P = .61), including the subgroup analysis performed on patients with pancreatic cancer (P = .60) and common duct strictures (P = .77). Complication rates were low in both groups (early: 3.7% N, 6.3% SS; late: 2.5% N, 3.1% SS). Ninety percent underwent chemotherapy and 38% radiation therapy in each group.LimitationsRetrospective design.ConclusionSimilar outcomes were achieved with N and SS stents regarding efficacy, duration of stent patency, occlusion rates, and complications. Our results are most applicable to patients with common duct strictures and pancreatic cancer.