Gradual stiffness versus magnetic imaging-guided variable stiffness colonoscopes: A randomized noninferiority trial

Abstract

Background: Colonoscopes with gradual stiffness have recently been developed to enhance cecal intubation.

Objective: We aimed to determine if the performance of gradual stiffness colonoscopes is noninferior to that of magnetic endoscopic imaging (MEI)-guided variable stiffness colonoscopes.

Methods: Consecutive patients were randomized to screening colonoscopy with Fujifilm gradual stiffness or Olympus MEI-guided variable stiffness colonoscopes. The primary endpoint was cecal intubation rate (noninferiority limit 5%). Secondary endpoints included cecal intubation time. We estimated absolute risk differences with 95% confidence intervals (CIs).

Results: We enrolled 475 patients: 222 randomized to the gradual stiffness instrument, and 253 to the MEI-guided variable stiffness instrument. Cecal intubation rate was 91.7% in the gradual stiffness group versus 95.6% in the variable stiffness group. The adjusted absolute risk for cecal intubation failure was 4.3% higher in the gradual stiffness group than in the variable stiffness group (upper CI border 8.1%). Median cecal intubation time was 13 minutes in the gradual stiffness group and 10 minutes in the variable stiffness group (p < 0.001).

Conclusions: The study is inconclusive with regard to noninferiority because the 95% CI for the difference in cecal intubation rate between the groups crosses the noninferiority margin. (ClinicalTrials.gov identifier: NCT01895504).

Keywords: Endoscopy; colonoscopy; innovation.

Figures

Figure 1.

Study flowchart. MEI: magnetic endoscopic imaging.

Figure 2.

Observed absolute risk difference for cecal intubation failure with the gradual stiffness colonoscope (test instrument) compared with the MEI-guided variable stiffness colonoscope (standard instrument) after adjustment for patient gender (patients with cecal intubation failure due to poor bowel preparation are excluded from the analysis). Error bar: one-sided 95% confidence interval; Δ: noninferiority margin.

Figure 3.

Patient pain during colonoscopy in the two treatment groups (p for trend = 0.26).