Single- versus double-balloon enteroscopy: the evidence base: Comment on Endoscopy essentials, Small-bowel endoscopy

Since the introduction of single-balloon enteroscopy (SBE) there has been an ongoing debate about its diagnostic yield and clinical impact in comparison with double-balloon enteroscopy (DBE). In the Endoscopy Essentials series, Andrea May recently published her interpretation of the current literature on small-bowel enteroscopy [1]. Her paper contains a number of statements that we would like to comment on.

To date, three RCTs have been published that compare the DBE and SBE techniques [2] [3] [4]. In only two of these investigations were the systems employed actually being used for their certified purpose (Fujinon EN-450T5 vs. Olympus SIF-Q180) [2] [4]; one of these was our publication [2].

May suggests that the “poor” results in our study, which she referred to as “the European multicenter study” [2], were due to lack of experience. Our study included a large number of patients (in fact, 130) gathered over a 12-month period at three European academic institutions [2]. As pointed out in the Methods section of our paper [2], investigators had conducted at least 50 SBE procedures before participating in the study. All participating centers had and continue to have high-volume endoscopy units with a depth of experience in small-bowel endoscopy; for example, in the past seven years at the University Hospitals of Muenster and Rotterdam over 3500 balloon-assisted enteroscopies have been performed in 2000 patients. All the group members have made important contributions to the scientific understanding and evaluation of enteroscopy techniques and complications. There might be a debate regarding the experience in SBE technique of the endoscopists who took part in the German multicenter study by May et al. [3], that showed a lower technical performance for SBE. In that study, the participating endoscopists only had a short course that introduced the SBE technique, 2 months before the start of the study.

May states that we changed the primary end point of our study. This is clearly not correct. “Complete small-bowel visualization” and “insertion depth” were both initial primary end points according to the study protocol. After the pilot study, the power analysis showed that “complete small-bowel visualization” was not a reasonable variable because of the very high patient numbers needed to achieve statistical significance. Therefore, we decided to use “insertion depth” as the only primary end point of our study. This is stated clearly in our paper [2]. The interim analysis that May mentions was done because of rumors in the German endoscopy community regarding safety issues with the SBE system, rumors that eventually proved to be unfounded [2].

Contrary to May’s statement [1], preliminary results from our study were emphatically not presented at the UEGW 2010 in Barcelona. In fact, only after completion of the study were our data presented at a national meeting in Stuttgart, Germany (DGVS 2011) and at the UEGW 2011 in London.

A decent review of the currently available literature shows that both systems have similar procedural characteristics [5]. The relatively low complete endoscopy rate (CER) in our study seems comparable to that found in the majority of other Western studies done with larger groups, i. e. > 40 patients, that have shown complete bowel visualization rates varying between 0 and 16 % [6] [7] [8] [9]. Differences in CER might be explained either by a different distribution of positive findings in Eastern and Western countries [10] or by different methods for calculating CER (achieved versus attempted or achieved versus whole study population). Nevertheless, the clinical importance of CER remains controversial [11]. In our opinion, the most important factor for evaluating clinical relevance is the diagnostic yield [5]; the two systems have never shown any differences with regard to diagnostic yield, leading to the conclusion that both systems are equally suitable in daily general gastroenterology practice.

At this stage, the data consistently do not show a clear clinical advantage of one enteroscopy system over the other. We strongly advocate that the scientific discussion of all current enteroscopy systems, including spiral enteroscopy, should be evidence-based rather than opinionbased.

• References

• 1 May A. Small-bowel endoscopy. Endoscopy 2012; 44: 375-377
• 2 Domagk D, Mensink P, Aktas H et al. Single- vs. double-balloon enteroscopy in small-bowel diagnostics: a randomized multicenter trial. Endoscopy 2011; 43: 472-476
• 3 May A, Farber M, Aschmoneit I et al. Prospective multicenter trial comparing push-and-pull enteroscopy with the single- and double-balloon techniques in patients with small-bowel disorders. Am J Gastroenterol 2010; 105: 575-581
• 4 Takano N, Yamada A, Watabe H et al. Single-balloon versus double-balloon endoscopy for achieving total enteroscopy: a randomized, controlled trial. Gastrointest Endosc 2011; 73: 734-739
• 5 Lenz P, Domagk D. Double- vs. single-balloon vs. spiral enteroscopy. Best Pract Res Clin Gastroenterol Hepatol 2012; 26: 303-313
• 6 Di Caro S, May A, Heine DG et al. The European experience with double-balloon enteroscopy: indications, methodology, safety, and clinical impact. Gastrointest Endosc 2005; 62: 545-550
• 7 Kaffes AJ, Koo JH, Meredith C. Double-balloon enteroscopy in the diagnosis and the management of small-bowel diseases: an initial experience in 40 patients. Gastrointest Endosc 2006; 63: 81-86
• 8 Monkemuller K, Weigt J, Treiber G et al. Diagnostic and therapeutic impact of double-balloon enteroscopy. Endoscopy 2006; 38: 67-72
• 9 Perez-Cuadrado E, Mas P, Hallal H et al. Double-balloon enteroscopy: a descriptive study of 50 explorations. Rev Esp Enferm Dig 2006; 98: 73-81
• 10 Xin L, Liao Z, Jiang YP et al. Indications, detectability, positive findings, total enteroscopy, and complications of diagnostic double-balloon endoscopy: a systematic review of data over the first decade of use. Gastrointest Endosc 2011; 74: 563-570
• 11 Xin L, Gao Y, Liao Z et al. The reasonable calculation of complete enteroscopy rate for balloon-assisted enteroscopy. Endoscopy 2011; 43: 832 ; author reply 832