History of Bariatric Surgery Is an Independent Risk Factor for Inadequate Colonoscopy Preparation

Introduction: Effective colon cancer screening requires adequate bowel preparation. In the setting of prior bariatric surgery, low-volume preparations or extended time delivery for high-volume preparations is recommended, although this recommendation is based on weak evidence. This study aims to evaluate bariatric surgery as a predictive risk factor for inadequate bowel preparation. Methods: Data were collected retrospectively for consecutive colonoscopies between March 1, 2013 and November 15, 2017. Only the index colonoscopy for each patient within the review period, and those scored using the Boston Bowel Preparation Scale (BBPS) were included. Incomplete data sets and patients with inflammatory bowel disease (IBD) were excluded. Inadequate preparation was defined as any one or more colon segments with a BBPS score of less than two. Patients with bariatric surgery occurring before the date of the colonoscopy were identified using ICD 9/10 codes. Data were analyzed using Wilcoxon rank-sum test for continuous variables and Fischer’s exact test for dichotomous variables. Multivariate logistic regression was performed to identify independent factors predictive of inadequate bowel preparation. Results: 70,714 colonoscopies occurred within the designated review period. 58,853 were excluded from analysis as shown in Figure 1. Of the remaining 11,861 colonoscopies, 363 (3.1%) had inadequate preparation. Factors associated with inadequate preparation on univariate analysis included: age, male sex, non-white race, body mass index (BMI), hypertension (HTN), diabetes mellitus (DM), and history of bariatric surgery (Table 1). After controlling for confounding risk factors, a history of bariatric surgery (OR = 2.98; 95% CI: 1.93-4.61) was found to be predictive of inadequate preparation (Table 1). In a subanalysis of malabsorptive vs. restrictive bariatric surgery patients, malabsorptive bariatric surgery was associated with a higher rate of inadequate preparation (12.79% vs. 4.58%, P = 0.023).515_A Figure 1 No Caption available.Conclusion: A history of bariatric surgery is an independent risk factor for inadequate bowel preparation. Furthermore, malabsorptive bariatric surgeries had higher rates of inadequate preparation when compared to restrictive bariatric surgeries. Further quality improvement initiatives should be directed at identifying the appropriate bowel preparation regimen in this population.515_B Figure 2. Risk factors for Inadequate Bowel Preparation.