Predictors of Inadequate Inpatient Colonoscopy Preparation and Its Association with Hospital Length of Stay and Costs

Background/aims: Adequate bowel preparation is essential to safe and effective inpatient colonoscopy. Predictors of poor inpatient colonoscopy preparation and the economic impacts of inadequate inpatient preparations are not defined. The aims of this study were to (1) determine risk factors for inadequate inpatient bowel preparations, and (2) examine the association between inadequate inpatient bowel preparation and hospital length of stay (LOS) and costs.

Methods: We performed a retrospective cohort study of adult patients undergoing inpatient colonoscopy preparation over 12 months (1/1/2013-12/31/2013).

Results: Of 524 identified patients, 22.3% had an inadequate preparation. A multiple logistic regression model identified the following potential predictors of inadequate bowel preparation: lower income (OR 1.11; 95% CI 1.04, 1.22), opiate or tricyclic antidepressant (TCA) use (OR 1.55; 0.98, 2.46), and afternoon colonoscopy (OR 1.66; 1.07, 2.59); as well as American Society of Anesthesiologists (ASA) class ≥3 (OR 1.15; 1.05, 1.25) and symptoms of nausea/vomiting (OR 1.14; 1.04, 1.25) when a fair preparation was considered inadequate. Inadequate bowel preparation was associated with significantly increased hospital LOS (model relative mean estimate 1.25; 95% CI 1.03, 1.51) and hospital costs (estimate 1.31; 1.03, 1.67) when compared to adequate preparations.

Conclusions: The rate of inadequate inpatient bowel preparations is high and associated with a significant increase in hospital LOS and costs. We identified five potential predictors of inadequate inpatient preparation: lower socioeconomic class, opiate/TCA use, afternoon colonoscopies, ASA class ≥3, and pre-preparation nausea/vomiting; these data should guide future initiatives to improve the quality of inpatient bowel preparations.