Koseiren Murakami General Hospital, Niigata; Scientific Research Works Peer Support Group, Osaka; Funabashi Orthopaedic Sports Medicine & Joint Centre, Chiba; Seichiryo Hospital, Nagoya, Japan
aDivision of Gastroenterology, Koseiren Murakami General Hospital, Niigata, Japan (Selim Coşkun); bScientific Research WorkS Peer Support Group (SRWS-PSG), Osaka, Japan (Selim Coşkun, Shota Hoshika, Masahiro Banno); cShoulder & Elbow Service, Funabashi Orthopaedic Sports Medicine & Joint Center, Chiba, Japan (Shota Hoshika); dDepartment of Psychiatry, Seichiryo Hospital,Nagoya,Japan (Masahiro Banno)
We read with interest the study by Leung et al regarding water exchange with distal attachments [1]. While the authors conclude that this combination optimizes the right-sided adenoma detection rate (ADR), several methodological issues suggest that these findings should be interpreted with caution.
First, the primary endpoint (overall ADR) did not reach statistical significance (P=0.05). The authors’ suggestion that the non-significant result for Endocuff Vision (P=0.057) was merely a Type II error is speculative. As emphasized by Amrhein et al [2], in rigorous clinical trials, results exceeding the P<0.05 threshold should not be framed as positive trends to justify clinical efficacy.
Second, the reported benefit in the right colon was a non-prespecified secondary outcome. According to the trial registration (NCT03566615), right-sided ADR was not a predefined endpoint. Highlighting this specific finding after a negative primary result raises concerns about selective reporting and the inflation of Type I error through multiple testing.
Furthermore, the 13-min mean withdrawal time significantly exceeds the 6-8 min guideline recommendation and the 9-min clinical average [3]. This prolonged inspection is likely to create a “ceiling effect” [4], where meticulous observation outweighs the incremental benefit of distal attachments, limiting the results’ generalizability to routine practice.
In summary, given the post- hoc nature of the significant findings, the borderline statistical results, and the non-standard withdrawal times, the conclusion that these modalities should be routinely used to optimize right-sided ADR is premature. A more conservative, hypothesis-generating tone would be more appropriate.
1. Leung F, Cadoni S, Chen L, et al. A prospective international multisite randomized controlled trial of water exchange with and without distal cap(s) in adenoma detection. Ann Gastroenterol 2026;39:104-113.
2. Amrhein V, Greenland S, McShane B. Scientists rise up against statistical significance. Nature 2019;567:305-307.
3. Garborg KK. How many minutes should we take for withdrawal - guideline recommendations and upcoming evidence. Best Pract Res Clin Gastroenterol 2026;80:102019.
4. Shaukat A, Rector TS, Church TR, et al. Longer withdrawal time is associated with a reduced incidence of interval cancer after screening colonoscopy. Gastroenterology 2015;149:952-957.