Comparative Analysis of Outpatient and Inpatient Bowel Preparation for Colonoscopy: Evaluating Quality Outcomes and Identifying Contributing Factors

Objective: Effective bowel preparation is crucial for a successful colonoscopy. Comparative analyses between inpatient and outpatient bowel preparations are limited and inconsistent. This study aimed to compare the outcomes of outpatient and inpatient bowel preparations and identify the factors contributing to suboptimal results.Material and Methods: A retrospective analysis of colonoscopy reports from a single surgeon at a provincial hospital in Thailand was conducted. Data were collected from patients aged 18 or older who underwent colonoscopies between July 2021 and June 2023. The parameters analyzed included demographic information, underlying diseases, bowel preparation methods, medications, and quality indicators. The Boston Bowel Preparation Scale (BBPS) was used to assess preparation quality.Results: Among the 222 patients included, 180 (81.1%) had outpatient and 42 (18.9%) had inpatient bowel preparation. Significant differences were found between the groups in age, BMI, underlying diseases, hemoglobin levels, symptoms, indications for colonoscopy, and choice of bowel preparation medication. Propensity score matching balanced baseline characteristics. In the matched cohort, the outpatient group had a higher rate of satisfactory bowel preparation (92.9%) compared to the inpatient group (78.6%), but this difference was not statistically significant (p-value=0.061). Within the inpatient subgroup, admission to a private room and choice of bowel preparation medication were linked to higher inadequate preparation likelihood.Conclusion: This study found no significant differences between inpatient and outpatient bowel preparation. However, there was a trend suggesting better quality with outpatient bowel preparation. Thus, focusing on improving nursing interventions and selecting appropriate medications for inpatient bowel preparation may be beneficial.