Predictors of Poor Bowel Preparation in Colonoscopy

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Purpose: A poorly prepared colon can lead to missed lesions and repeated procedures that increase cost and complication risk. The aim of the study was to identify predictive factors of poor colon prep, including obesity, which increases risk of neoplasia. Methods: Retrospective review of 1815 reports of inpatient (IP) and outpatient (OP) colonoscopies performed from June to October 2007 at a tertiary referral center. Prior colectomy, repeat colonoscopy, incomplete reports were excluded and 1588 reports analyzed. The endoscopist's inability to adequately evaluate the entire colonic mucosa and request for earlier than expected repeat colonoscopy (ACG, ASGE guidelines) were used to determine a poor or inadequate prep (PIP). Results: Good to excellent prep quality was reported in 400 (25.2%) patients and PIP in 627 (39.5%) patients. Patients with PIP were older (59.57 ± 13.5 yrs) and had higher weight (86.19 ± 23.9 kg) and BMI (29.74 ± 7.84 kg/m2) (P < .01). In univariate analysis, male gender, inpatient status (IP), Polyethylene glycol based lavage (PEG), smoking, lack of regular alcohol consumption, diabetes mellitus (DM), hypertension, coronary artery disease (CAD) increased BMI, depression, mental retardation (MR) and use of anti-depressant medications or narcotics were predictive of PIP. However, in multivariate logistic regression analysis, only male gender (OR = 0.75, P= 0.02), IP status (OR = 1.92, P= 0.002), smoking (OR = 1.62, P= 0.003), lack of regular alcohol consumption (OR = 0.68, P= 0.0003), DM (OR = 1.64, P= 0.0006), MR (OR = 3.54, P= 0.0004), narcotic use (OR = 3.04, P < 0.0001), and PEG (OR = 0.53, P= 0.0004) were predictors of poor bowel preparation. Modeling for composite outcome using univariate analysis: older age, male gender, IP status, smoking, lack of regular alcohol consumption, DM, hypertension, CAD, increased BMI, depression, obstructive sleep apnea, MR and consumption of anti-depressant medications or narcotics were predictive of PIP. However, in multivariate logistic regression analysis, only older age (OR = 1.009, P= 0.01), male gender (OR = 0.71, P= 0.002), IP status (OR = 1.55, P= 0.008), smoking (OR = 1.35, P= 0.01), lack of regular alcohol consumption (OR = 0.7, P= 0.01), increased BMI (OR = 1.02, P= 0.004), MR (OR = 2.17, P= 0.03), use of antidepressant medication (OR = 1.69, P= 0.001), and narcotic use (OR = 2.1, P= 0.001) were predictors of PIP. Conclusion: Poorly prepped colons reduce diagnostic yield. Aborted and repeat procedures greatly increase the cost of colonoscopy. Prior identification and aggressive bowel cleansing of patients with predictive factors of PIP can lead to improved diagnostic yield and cost savings. This needs to be verified in a prospective study.