Introduction: Self-expandable metal stents (SEMS) are commonly used in the management of malignant biliary obstruction due to higher patency rates compared to plastic stents. Development of covered SEMS (CSEMS) has led to extended stent patency compared to uncovered SEMS (USEMS). However, there are concerns that deployment of CSEMS may be associated with higher risk of post-ERCP pancreatitis (PEP), acute cholecystitis, and stent migration. We performed this meta-analysis to assess the risk of post-ERCP pancreatitis and other adverse events with biliary CSEMS compared to USEMS.
Methods: We searched electronic databases from January 1989 to June 2014 for all the randomized controlled trials (RCT), prospective, and retrospective studies comparing the risk of PEP and other adverse events following the placement of covered SEMS versus uncovered SEMS in patients with biliary obstruction. Studies in which biliary stents were placed by non-endoscopic techniques were excluded. The Mantel-Haenszel method was used to pool data of PEP outcomes into random effect model meta-analyses. Odds ratios (ORs) with confidence intervals (CIs), and risk difference analysis when studies reported no events in either arm, were used to generate an overall effect estimate of outcome. Publication bias and heterogeneity were assessed by contour funnel plot and the I2 test, respectively.
Results: Eight studies (6 RCTs and 2 observational studies) with a total of 1,078 patients were included in the analysis. There was no heterogeneity or publication bias as shown by funnel plot for the risk of PEP, acute cholecystitis, and cholangitis. The analysis was limited by heterogeneity in stent migration. Our analysis did not show a significant difference between the type of stent and the risk of post-ERCP pancreatitis (OR 1.58; 95% CI 0.65-3.86), cholangitis (OR 0.98; 95% CI 0.46-2.09), and acute cholecystitis (OR 1.42; 95% CI 0.59-3.43). The risk of stent migration was significantly higher in CSEMS group (Figure 1).
Conclusion: Placement of covered SEMS is not associated with an increased risk of post-ERCP pancreatitis compared to uncovered SEMS. The risk of stent migration is significantly higher with covered SEMS.