"We aimed to identify factors associated with the decision to repeat the examination early after a colonoscopy done with suboptimal bowel preparation. We also aimed to quantify adenoma miss rates among those pairs of colonoscopies separated by an interval shorter than the time suggested by current guidelines, which assume an optimal bowel preparation," said study lead author Benjamin Lebwohl, MD, MS, Columbia University Medical Center, New York, N.Y. "Our findings of a miss rate of 42 percent for all adenomas and 27 percent for advanced adenomas suggest that suboptimal bowel preparation has a substantial harmful impact on the effectiveness of colonoscopy, and follow-up examination within one year should be considered. Because neoplastic findings on the initial colonoscopy were associated with a greater miss rate, a repeat examination within one year is indicated when an adenoma is found during a colonoscopy with suboptimal bowel preparation."
This retrospective analysis was conducted at Columbia University Medical Center, a tertiary-care institution in New York City. All colonoscopy procedures performed since the implementation of an electronic database on March 21, 2006, until Dec. 31, 2008, were reviewed. The end date allowed for a minimum follow-up observation period of one year to Dec. 31, 2009.
The study objective was to identify factors associated with early repeat colonoscopy after initial examinations with suboptimal preparations and to measure adenoma miss rates in this context. Early repeat colonoscopy was defined as any colonoscopy that was performed within three years of the initial examination. Three years is the shortest interval recommended in the current guidelines for surveillance colonoscopy in patients with a completely excised advanced adenoma or multiple adenomas found on the initial examination. In turn, any colonoscopy repeated before three years represents an examination repeated earlier than suggested by guidelines. Sensitivity analyses also were performed by using a more stringent definition of an early repeat examination, which was one repeated within one year of the initial examination.
To quantify the yield of repeating the colonoscopy early in terms of adenoma detection, the researchers included all patients in whom the cecum was reached on both the initial and repeat examination and in whom bowel preparation quality was considered optimal on the repeat examination. Adenoma miss rates for repeated colonoscopies were calculated by dividing the total number of adenomas found on the second colonoscopy by the total number of adenomas found on the index colonoscopy plus the second colonoscopy.