Bowel Preparation, Colonoscopy Withdrawal Time and Adenoma Detection Rate: A Prospective Study of Screening Colonoscopies

Abstract

There are few studies on the determinants of poor bowel preparation among colorectal cancer screening participants, and current evidence on the association between bowel preparation and adenoma detection was inconclusive. We evaluated the independent factors associated with poor bowel preparation and its impact on adenoma detection. We included asymptomatic subjects aged between 50-70 years who self-referred for colorectal cancer screening and received colonoscopy between 2008 and 2012 in Hong Kong. The quality of the bowel preparation was assessed by colonoscopists, and the factors associated with poor bowel cleansing were evaluated by binary logistic regression analyses. A multivariate regression model was constructed to evaluate if poor bowel preparation was associated with detection of colorectal neoplasia. From 5,470 screening participants with an average age of 57.7 years (SD 4.9), up to 34.6% had poor or fair bowel preparation. The level of poor or fair bowel preparation was as high as 34.6%. After controlling for sociodemographic and clinical factors, older age (≥ 60 years; adjusted odds ratio [AOR]=1.19 to 1.38, P = .017-0.038), male gender (AOR=1.38, 95% C.I. 1.19-1.60, P < .001), and smokers (AOR=1.41, 95% C.I. 1.14-1.75, P = .002) were significantly associated with poor or fair bowel preparation. Poorer cleansing led to longer caecal intubation time and colonoscopy withdrawal time, yet resulted in significantly lower detection rates of colorectal neoplasia (AOR=0.35 to 0.62) and colorectal advanced neoplasia (AOR=0.39 to 0.50) irrespective of their diameter (< 5mm or ≥ 5mm). Steps to improve proper procedures of bowel preparation are warranted, especially among subjects at risk of poor bowel preparation. These include more intensive preparation protocols and measures to improve patient understanding of bowel preparation as parts of continuous quality-improvement programmes. This study supports bowel preparation as a definite quality indicator.