Mo1502 Predictors of Unscheduled Events (Early Stent Occlusion) Among Plastic Biliary Stents Mouen Khashab, Anne Marie Lennon, Susan Hutfless, Katherine J. Kim, Sanjay Jagannath, Marcia Canto, Patrick I. Okolo, Kerry B. Dunbar, Vikesh K. Singh Johns Hopkins Medical Institute, Baltimore, MD; Mercy Medical Center, Baltimore, MD Background: Plastic stents are commonly used to treat biliary pathologies. A major disadvantage of plastic stents is their short patency rates. The aim of this study was to identify predictors of unscheduled events (early stent occlusion) among both conventional and wing stents. Methods: Patients with biliary pathology that necessitated biliary stenting at Johns Hopkins Hospital during the period 2003-2009 were considered for inclusion in the study. Those who underwent placement of a self-expandable metallic stent, who were lost to follow-up or died were excluded. Patients were stratified as having benign biliary strictures (group 1), malignant biliary strictures (group 2), or benign biliary non-stricture pathologies (group 3). Unscheduled events were defined as worsening cholestatic liver test results of significant severity to warrant ERCP with stent exchange prior to the planned stent exchange (usually at a three month interval), or symptoms of cholangitis. The association of stent type, stent number and diameter, demographics, Charlson Comorbidity Index (CCI), history of prior unscheduled events, presence of gallbladder, and performance of sphincteromy with the occurrence of unscheduled events was studied using logistic regression and multivariate analysis. Results: During the study period, 346 patients (mean age 58.3 years, females 47.7%) underwent 612 ERCP procedures with placement of plastic biliary stent(s). A total of 537 conventional plastic stents and 75 wing stents were placed. The broad indications for stent placement were benign biliary strictures in 41.7% (group 1), malignant biliary strictures in 29.1% (group 2), and various benign non-stricture biliary pathologies in 29.2% (group 3). Overall, only prior history of unscheduled events (OR 3.02, 95% CI 1.61-5-65, p 0.001) and CCI (OR 1.15, 95% CI 1.04-1.28, p 0.007) were associated with occurrence of subsequent unscheduled events (premature occlusion) on multivariate analysis. In group 2, but not groups 1 or 3, prior history of unscheduled events (OR 2.44, 95% CI 1.02-5.85, p 0.04) and CCI (OR 1.23, 95% CI 1.03-1.46, p 0.02) were factors associated with subsequent unscheduled events. Conclusions: Prior unscheduled events (early stent occlusion) and CCI were significantly associated with subsequent unscheduled events in patients with malignant biliary strictures. Physicians should consider early elective stent exchange in patients with malignant biliary strictures and prior early stent occlusion.