Runway Times Predicts Inpatient Bowel Preparation Quality

Abstract

Introduction: Incomplete bowel preparation for colonoscopy can lead to a reduction in adenoma detection, increased length of procedure and increased complication rates. Inpatient status is a known risk factor for suboptimal bowel preparation. We aimed to determine whether runway time (time from initiation of bowel preparation to procedure) affects inpatient bowel preparation quality. Methods: We conducted a retrospective study of patients undergoing inpatient colonoscopy from 7/1/2012 - 7/1/2015 at a single academic medical center. Descriptive statistics, Wilcoxon rank sum and chi-square tests were used to evaluate differences in the characteristics between adequate and inadequate bowel preparations. Multivariable logistic analysis was performed to adjust for variables related to adequate preparation in univariate analysis. Results: 242 randomly chosen colonoscopies meeting inclusion criteria were reviewed, of which 46% had an inadequate (fair, poor, unsatisfactory) bowel preparation (Table 1). Median runway time was 18 versus 20.5 hours for adequate and inadequate preparations (p= 0.013) (Figure 1). When runway time was dichotomized, a negative trend in bowel preparation quality was observed with 61.0% versus 48.9% having adequate preparations, for runway times of less than and greater than 18 hours, respectively (p= 0.083). This difference became significant in the multivariate logistic regression model, with an odds ratio of 1.73 (p= 0.05). Furthermore, an inadequate bowel preparation was associated with lower rates of successful colonoscopy (p < 0.001), higher rates of repeat colonoscopy (p=0.002), and longer length of inpatient stay (p=0.006) (Table 2). Sensitivity analysis defining “fair” as an adequate bowel preparation revealed fewer differences between adequate and inadequate preparations, suggesting that “fair” is different from “good” or “excellent” on the Aronchick scale.Figure 1Table 1: Baseline characteristics (median(IQR) or N(%))Table 2: Post-Colonoscopy OutcomesConclusion: This is the first study that demonstrates shorter runway time is associated with an adequate bowel preparation in the inpatient setting. Furthermore, this is one of the first studies to show that “fair” on the Aronchick scale is more similar to “poor”/“unsatisfactory” than “excellent”/“good” bowel preparations. Prospective studies are needed to validate the critical threshold for inpatient runway time. Study limitations include its retrospective nature and the small sample of subjects with runway time less than 12 hours.