Multicenter study evaluating factors for stent patency in patients with malignant biliary strictures: development of a simple score model

Background Self-expanding metal stents (SEMS) are known to have a significantly higher patency rate than plastic stents. We aimed to identify prognostic factors, besides stent type, for stent patency and to develop a score model that could further aid in guiding stent choice for the palliation of a malignant biliary stricture. Methods A retrospective multicenter study was conducted. Data on consecutive patients who had a stent placed between January 2002 and July 2009 were collected. Cumulative stent occlusion rates were analyzed by Kaplan-Meier curves and log rank testing, and prognostic factors were assessed by Cox regression analysis. Results A total of 690 stents (512 plastic stents, 174 SEMS) were endoscopically placed in 390 patients. At 8 weeks, stent occlusion had occurred in 32% of the plastic stents and 11% of the SEMS. Multivariate analysis indicated that plastic stents (hazard ratio [HR] 2.5, 95% confidence interval [CI] 1.9-3.5), a tight stricture requiring preceding dilation (HR 1.8, 95% CI 1.3-2.5), and a high initial bilirubin level (>50 mu mol/L (HR 1.3, 95% CI 1.0-1.7) were independently associated with an increased risk of stent occlusion. A score model based on these 3 factors was able to distinguish between stent procedures with a relatively high and low risk of stent occlusion (median 14 vs. 26 weeks, respectively). Conclusion Besides plastic stents, stricture severity requiring preceding dilation, and initial higher bilirubin level were associated with a shorter period of stent patency. A simple score model based on these factors was able to predict stent occlusion and may aid in choosing the most appropriate stent type in individual patients.