Summary of evidence
To our knowledge, this is the first systematic review and meta-analysis including only RCTs that compared EUS-guidance and ERCP as the primary approach to biliary drainage in cases of MBO. Our strict methodology, which included critical appraisal of biases, quality of evidence assessment, and a report prepared in accordance with the PRISMA guidelines, underscores the strength of our findings.
EUS-guided biliary drainage was first introduced as an alternative to be employed after ERCP failure[11–13]. Moole et al recently published a systematic review and meta-analysis comparing PTBD and EUS-guided drainage as alternatives to be employed after failed ERCP, demonstrating that the latter was superior, as has been cor-roborated by other authors.
Because of improvements in the technique and accessories over time, some authors have reported EUS-guided biliary drainage as a first-line modality in patients presenting with factors predictive of difficult biliary access by ERCP (e.g., altered anatomy, duodenal obstruction, and previous duodenal stent)[24–28]. Okuno et al published a prospective study of 20 patients undergoing EUS-guided hepa-ticogastrostomy with a 6-mm self-expanding metallic stent. The rates of technical success, clinical success, and adverse events were 100%, 95%, and 15%, respectively. In a recent multicenter cohort study, EUS-guided biliary drainage was compared with ERCP in patients with an indwelling duodenal stent. The authors identified a trend toward higher technical and clinical success rates in the EUS group and found no difference regarding adverse events. Finally, Nakai et al published a retrospective study comparing primary and rescue EUS-guided biliary drainage in terms of the rates of technical success and adverse events, both of which the authors found to be similar between the two approaches.
In a recent retrospective study of patients with distal biliary obstruction, Kawabuto et al demonstrated that EUS-guided choledochoduodenostomy was similar to transpapillary stenting in terms of the rates of clinical success and adverse events, although the duration of the procedure was shorter and there were no cases of pancreatitis among the patients submitted to the former. Therefore, the EUS-guided procedure was considered a plausible first-line method to address MBO. Subsequent RCTs comparing those techniques have shed light on the matter[14-16].
The availability of three high-quality RCTs allowed us to perform a consistent meta-analysis that will likely contribute to making daily practice more evidence based. Our analysis of technical success is extremely reliable because of the similar definitions employed and homogenous results among the three studies. However, the clinical success analysis lacked consistency because of indirectness due to different outcome definitions. In addition, Bang et al included cross-over procedures in the data report, which impeded the intention-to-treat analysis. Therefore, caution should be taken in drawing conclusions based on the results of this analysis.
During our evaluation of the duration of procedures, we found high heterogeneity among the studies. Such true heterogeneity is likely attributable to the participation of endoscopists with different levels of expertise. In addition, various stents have been used in biliary drainage. Paik et al employed insulated delivery systems to perform EUS-guided drainage, which probably shortened the duration of the procedure in their EUS group and promoted heterogeneity. Our analysis showed equivalence between the two methods regarding the duration of the procedure. It should be borne in mind that, whereas ERCP is a well-established technique, EUS-guided drainage is still in development, and its duration could therefore become shorter in the near future.
As to the safety of the procedure, our analysis showed similar rates of adverse events after EUS and ERCP. Although there was no difference between the two approaches regarding the overall rates, there was a substantial difference regarding the types of adverse events observed. In the ERCP group, the most common complication was pancreatitis, which was not reported in the EUS group. Conversely, pneumoperitoneum and biliary peritonitis were reported only in the EUS group, although none of patients required surgical intervention. Cholangitis was reported in both groups: 7 cases in the ERCP group and 4 in the EUS group.
The stent patency was equivalent for both methods, although the largest study did not provide standard deviation values and was therefore excluded. That significantly reduced the size of the sample evaluated in the stent patency analysis.
Finally, the results of our analysis of the stent dysfunction rate favored EUS-guided drainage. That might be explained by the fact that this method allows a puncture far from the tumor rather than through it, thus avoiding tumor ingrowth or overgrowth. Although EUS-guided drainage can promote stent dysfunction due to food bolus impaction, that risk does not seem to outweigh its advantages. It should also be borne in mind that the employment of diverse stents for biliary drainage could be a confounding factor in the analysis of stent patency and dysfunction.
None of the RCTs evaluated in our systematic review described a cost-effectiveness analysis. Because the differences between ERCP and EUS-guided drainage are still slight, such information might create a tipping point to recommend one approach over the other. Future trials should address this knowledge gap.