Study design:
The study is designed as a multicenter randomized controlled trial. The participating centers are Rikshospitalet University Hospital (Dept. of Gastroenterology), Oslo, Norway, University Hospital Muenster (Dept. of Medicine B), Muenster, Germany and Erasmus Medical Center, Rotterdam, The Netherlands.
Randomization:
Randomization to SBE or DBE is performed on basis of the individual participant. Equally large groups are randomized using block randomization (blocks of six patients) for each of the participating centers. Randomization (using SPSS statistical software package) is performed by an independent researcher, who is not part of the endoscopy team.
Double-balloon procedure:
DBE is performed using the DBE T-type endoscope system (Fujinon Inc, Japan), as described in the literature. The DBE endoscope consist of a 200-cm long video endoscope with an outer diameter of 8.5 mm and a flexible overtube with a length of 145 cm and an outer diameter of 12 mm. Latex balloons are attached to both the endoscope and the overtube. These balloons are inflated and deflated during insertion, as described elsewhere in detail.
Single-balloon procedure:
SBE is performed using the SBE endoscope system (SIF-Q180, Olympus Optical Co., Ltd., Tokyo, Japan). The SBE endoscope consist of a 200-cm long video endoscope with an outer diameter of 9.2 mm and a flexible overtube with a length of 140 cm and an outer diameter of 13.2 mm. One single balloon is attached to the the tip of the overtube. The insertion process follows the method used for DBE, but instead of inflation of the endoscope balloon, the tip of the endoscope is angulated at straightening.
Ethics:
The regional ethics committees of the participating centers will be asked for approval of the study protocol.
Power analysis:
The present study is a non-inferiority study, aiming on showing equality between the two endoscope systems with regard to the main endpoints. A pilot study including 20 patients in each group will be performed since there is no data in present literature with respect to the main endpoints. The difference in percentage of complete visualization between the two groups will be used as the power-driving endpoint. The results of the pilot study will then be used for power calculation of the study applying the no inferiority-thesis. P-values of < 0.05 will be considered statistically significant.
Ad addendum:
The manufacturer of one of the instruments on the present trial (Olympus) approached the investigators in late January 2009 about a possible risk of increased adverse events with the Olympus endoscope. The company was not aware of any details regarding the nature of these events or the magnitude of this potential risk, as the warning was solely based on unpublished rumors in the GI community. To prevent participants in the present trial from any harm, the investigators decided to perform an interim analysis including all patients included in the trial until February 1, 2009, to rule out possible adverse events or poor performance in one or both of the involved treatment arms. No stopping rules apply for this interim analysis.
