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Non-superiority of lumen-apposing metal stents: Is the evidence conclusive?
  1. Lotte Boxhoorn,
  2. Paul Fockens,
  3. Rogier P Voermans
  1. Department of Gastroenterology & Hepatology, Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
  1. Correspondence to Dr Rogier P Voermans, Department of Gastroenterology & Hepatology, Amsterdam UMC, Meibergdreef 9, 1105 AZ Amsterdam,The Netherlands; r.p.voermans{at}

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With great interest we have read the work of Bang et al, comparing the efficacy of lumen-apposing metal stents (LAMS) and double-pigtail plastic stents (DPS) for endoscopic drainage of walled-off necrosis (WON).1 We congratulate the authors on completing the first randomised controlled trial comparing these two drainage strategies. They found no difference in the total number of procedures needed to achieve treatment success at 6-month follow-up. However, we feel that three important limitations have not been mentioned in the discussion.

First, we question whether the potential benefits of LAMS could have been proven in the included study population. The larger calibre lumen of the LAMS allows spontaneous drainage of necrotic tissue, hypothetically reducing the need for endoscopic necrosectomy. Bang et al indeed demonstrated a very low number of endoscopic necrosectomies in patients treated with LAMS (13%), but also an unusual low number of endoscopic necrosectomies in patients drained with DPS (21%). This is not in line with reported necrosectomy rates in literature (50%–60%) and indicates a possible selection bias.2 We doubt whether potential advantages of LAMS over DPS could have been demonstrated in a study population needing so few necrosectomies.

Second, patients with infected as well as symptomatic sterile WON were included. Although this concerned the minority of included patients (13% drained with LAMS and 10% with DPS), it should be underlined that infection of WON significantly increases the risk of organ failure and mortality.3 Clinical courses of patients with infected and symptomatic sterile WON are not comparable. Results, however, were not differentiated between these patients and therefore potential confounding effects could not be determined.

Finally, the authors did not describe the timing of drainage. Necrotic debris is known to become more liquified over time. Theoretically, the larger lumen of LAMS is therefore less relevant in longer standing WON with more liquified content. Difference in timing of intervention between the LAMS and DPS group could have affected the need for additional interventions. Although the authors calculated the degree of necrosis present in the collections, this is in our experience often unreliable.

In conclusion, a potential selection bias as well as possible variance in timing could have influenced primary outcome (number of procedures needed). From our perspective, the potential benefit of LAMS could not have been proven in patients needing so few necrosectomies. Therefore, the question whether the use of a large diameter LAMS would have lowered the need for necrosectomies in patients with WON still remains unanswered.


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  • Contributors Drafting of manuscript: LB, PF and RPV.

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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