Yaseen Alastal, Tariq Hammad, Muhammad Ali Khan, Basmah W Khalil, Sobia Khan, Mohammad Kashif Ismail, Ali Nawras, Aijaz Sofi
Background Self-expandable metal stents are commonly used in the management of malignant biliary obstruction due to higher patency rates compared to plastic stents. Development of covered self-expandable metal stents has led to extended stent patency compared to uncovered self-expandable metal stents. However, there are concerns that deployment of covered self-expandable metal stents may be associated with higher risk of post-endoscopic retrograde cholangio-pancreatography pancreatitis, acute cholecystitis and stent migration. Objective We performed this meta-analysis to assess the risk of post-endoscopic retrograde cholangio-pancreatography pancreatitis and other adverse events (acute cholecystitis and stent migration) with biliary covered self-expandable metal stents compared to uncovered self-expandable metal stents. We also assessed the proportion of stent patency at 6 and 12 months between the two groups. Methods We searched MedLine, EMBASE, Cochrane database, ISI Web of Science and Scopus from January 1989 through June, 2014, to identify randomized controlled trials and observational studies that provided data on the risk of post-endoscopic retrograde cholangio-pancreatography pancreatitis and other adverse events following the placement of covered self-expandable metal stents versus uncovered self-expandable metal stents in patients with biliary obstruction. The Mantel–Haenszel method was used to pool data of post-endoscopic retrograde cholangio- pancreatography pancreatitis, acute cholecystitis, stent migration and proportion of stent patency over 6 and 12 months into fixed or random effect model of meta-analyses. Odds ratio was used to generate an overall effect estimate of the outcome. Results Eight studies (6 randomized controlled trials and 2 observational studies) with a total of 1078 patients were included in the meta-analysis. The pooled odds ratio with 95% confidence intervals for risk of post-endoscopic retrograde cholangio-pancreatography pancreatitis with covered versus uncovered self-expandable metal stents was 1.58 (0.65 to 3.86); (Cochran Q test P=0.60, I2=0%). Stent migration was significantly associated with covered self-expandable metal stents, pooled odds ratio with 95% confidence intervals was 10.07 (3.30 to 30.70); (Cochran Q test P=0.80, I2=0%). There was no difference in the risk of acute cholecystitis with either type of stent. Pooled odds ratio with 95% confidence intervals was 1.42 (0.59 to 3.43); (Cochran Q test P=0.75, I2=0%). There was no difference in proportion of stent patency at 6 or 12 months. For 6 months the pooled odds ratio with 95% confidence intervals was 1.55 (0.75 to 3.22); (Cochran Q test P=0.01, I2=68%) and for 12 months the pooled odds ratio with 95% confidence intervals was 1.17 (0.66 to 2.07); (Cochran Q test P=0.03, I2=66%). Conclusion This meta-analysis failed to show any association for risk of post-endoscopic retrograde cholangio-pancreatography pancreatitis and acute cholecystitis with use of covered versus uncovered self-expandable metal stents. However, covered self-expandable metal stents was significantly associated with stent migration. There was no superior patency of covered self-expandable metal stents in comparison to uncovered self-expandable metal stents over 6 and 12 months.
