Comparative analysis of bowel preparation quality for colonoscopy: a survey of outpatients and inpatients

BACKGROUND: The quality of bowel preparation significantly affects the outcome of colonoscopy. Adequate bowel cleansing improves diagnostic accuracy while reducing the need for repeat procedures. Currently, evidence regarding factors associated with inadequate bowel preparation in outpatients and inpatients remains limited. Therefore, this study aimed to compare the quality of bowel preparation between outpatients and inpatients undergoing colonoscopy and to identify risk factors for inadequate bowel preparation. METHODS: A total of 20,688 patients undergoing sedated colonoscopy were included in this study. Bowel preparation quality was assessed using the Boston Bowel Preparation Scale (BBPS). Propensity score matching (PSM) was used to adjust the baseline differences between the outpatients and inpatients, followed by univariate and multivariate logistic regression analyses to assess risk factors for inadequate bowel preparation. Subgroup analyses were conducted to analyze the differences in bowel preparation quality between outpatients and inpatients. RESULTS: After matching, outpatients had higher BBPS scores than inpatients (7.29 ± 1.06 vs. 6.97 ± 1.19, P < 0.001), and had a higher rate of adequate bowel preparation compared with inpatients (95.95% vs. 93.07%, P < 0.001). Univariate analysis showed that aged ≥ 65 years, ethnic minorities, inpatient status, diabetes, and a history of abdominal surgery were significantly related to inadequate bowel preparation (all P < 0.001). Multivariate analysis showed that aged ≥ 65 years (OR: 1.90; 95% CI: 1.52–2.39; P < 0.001), ethnic minorities (OR: 4.22; 95% CI: 2.91–6.12; P < 0.001), inpatient status (OR: 1.52; 95% CI: 1.23–1.89; P < 0.001), diabetes (OR: 1.86; 95% CI: 1.13–3.06; P < 0.001) and a history of abdominal surgery (OR: 1.55; 95% CI: 1.25–1.93; P < 0.001) were independent risk factors for inadequate bowel preparation. Subgroup analysis showed that rates of bowel preparation adequacy were significantly higher in outpatients than in inpatients. CONCLUSIONS: Although bowel preparation quality was statistically lower in inpatients than in outpatients, the absolute difference was modest. Aged ≥ 65 years, ethnic minorities, inpatient status, diabetes, and a history of abdominal surgery were independent risk factors for inadequate bowel preparation. Clinical attention should be directed toward patients who present with a combination of these risk factors, which tend to occur more frequently in inpatient settings, to implement individualized preparation strategies.