Risk of post-ERCP pancreatitis with placement of self-expandable metallic stents

Background: There are conflicting data on the risk of post-ERCP pancreatitis (PEP) related to self-expandable metallic stents (SEMSs). Objective: To compare rates of PEP in patients who undergo biliary drainage with SEMSs or polyethylene stents (PSs). Design: Retrospective, cohort study. Setting: Tertiary-care medical center. Patients: This study involved patients undergoing ERCP for malignant biliary obstruction between January 2005 and October 2008. Intervention: First-time placement of a SEMS or PS for biliary decompression. Main Outcome Measurements: Early post-ERCP complications, particularly PEP. Results: We identified 544 eligible patients, 248 SEMSs (102 covered), and 296 PSs. The etiology of malignant biliary obstruction was similar between groups, with 55% from pancreatic cancer. The frequency of PEP was significantly higher in the SEMS group (7.3%) versus the PS group (1.3%) (OR 5.7 [95% CI, 1.9-17.1]). On univariate analysis, patient age of <40 years, a history of PEP, and at least 1 pancreatic duct injection were also significant predictors of PEP, whereas female sex and having pancreatic cancer were not. When significant variables were added to a multiple-predictor regression model, the odds of PEP from SEMS placement increased to 6.8 (95% CI, 2.2, 21.4). However, the frequency of PEP was similar between covered (6.9%) and uncovered (7.5%) SEMSs (OR 0.9 [CI, 0.3-2.4]). Purported SEMS-specific risk factors, including the use of cSEMSs, overlapping SEMSs, or having a biliary sphincterotomy were not found to be significant contributors to the higher risk. Limitations: Retrospective design. Conclusion: After we controlled for confounding variables, the frequency of PEP was significantly higher with placement of a SEMS compared with a PS. Rates of PEP were comparable with use of covered and uncovered SEMSs.