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Caution should be exercised in denying the protective effect of clip closure on post-EMR perforation of a proximal large nonpedunculated colorectal polyp

      To the Editor:
      We read with great interest the article by Forbes et al
      • Forbes N.
      • Gupta S.
      • Frehlich L.
      • et al.
      Clip closure to prevent adverse events following endoscopic mucosal resection of proximal large non-pedunculated colorectal polyps: meta-analysis of individual patient data from randomized controlled trials.
      entitled “Clip closure to prevent adverse events following endoscopic mucosal resection of proximal large non-pedunculated colorectal polyps: meta-analysis of individual patient data from randomized controlled trials.” By representing 1248 patients with proximal large nonpedunculated colorectal polyps (LNPCPs) from 4 randomized controlled trials, the authors concluded that preventive clipping could effectively prevent the bleeding after EMR of proximal LNPCPs. We would like to share our reservations about the results of this study.
      In addition to the above result, the author further discovered nonbleeding adverse events and concluded that clipping did not affect perforation because traditional meta-analyses showed that the relative risk of perforation was 0.76 (95% CI, 0.17-3.38), and by analyzing individual data on 1150 patients, the odds ratio of perforation was 0.78 (95% CI, 0.17-3.54).
      However, there is a problem that cannot be ignored: the incidence of perforation after colonic EMR of lesions >2 cm was only 1.5%,
      • Turan A.S.
      • Ultee G.
      • Van Geenen E.J.M.
      • et al.
      Clips for managing perforation and bleeding after colorectal endoscopic mucosal resection.
      and the event rate of perforation in this overall cohort was only 0.6%. The low event rate may result in a type II statistical concern and makes it difficult to accurately assess. Thus, caution should be taken in concluding that preventive clipping is not associated with perforation. Additionally, whether clipping affects perforation should be discussed with other previous studies in the discussion section to enable a more rigorous conclusion to be drawn.
      Overall, we think that whether preventive clipping is associated with perforation should be interpreted with caution.

      Disclosure

      All authors disclosed no financial relationships.

      References

        • Forbes N.
        • Gupta S.
        • Frehlich L.
        • et al.
        Clip closure to prevent adverse events following endoscopic mucosal resection of proximal large non-pedunculated colorectal polyps: meta-analysis of individual patient data from randomized controlled trials.
        Gastrointest Endosc. 2022; 96: 721-731
        • Turan A.S.
        • Ultee G.
        • Van Geenen E.J.M.
        • et al.
        Clips for managing perforation and bleeding after colorectal endoscopic mucosal resection.
        Expert Rev Med Devices. 2019; 16: 493-501

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      • Response
        Gastrointestinal EndoscopyVol. 96Issue 6
        • Preview
          We thank Deng et al1 for their interest in our meta-analysis2 and for their letter to the editor. In their letter, the authors raise concerns regarding our observed result that prophylactic clip closure was not associated with the incidence of delayed perforation after EMR of proximal large nonpedunculated colorectal polyps (LNPCPs). Deng et al correctly point out that a type II error could potentially be responsible for the lack of association between clipping and perforation, given the low event rate of 0.6%.
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