IntroductionUsing real-world data, we compared the quality of bowel preparation instructed by the digestive and non-digestive physicians in outpatients for colonoscopy and identified potential risk factors.MethodsThis was a retrospective study based on real-world data, which were collected from the Ningbo First Hospital in China from December 2019 to October 2020. Outpatients included were classified into the digestive and the non-digestive physician groups according to the referring physician. The primary outcome was adequate bowel preparation measured by the Boston Bowel Preparation Scale (BBPS), namely, a BBPS score of 2 or higher in any colonic segment and a total score ≥ 6. Secondary outcomes included the total mean BBPS scores and possible risk factors associated with poor bowel preparation.ResultsThere were 671 outpatients included, with 392 in the digestive physician group and 279 in the non-digestive physician group. Adequate bowel preparation was 84.2% in the digestive physician group and 71.0% in the non-digestive physician group (odds ratio [OR]: 1.50, p < 0.001), and the latter had lower total mean BBPS scores (6.12 ± 1.33 vs. 6.66 ± 1.29, p < 0.001). The non-digestive physician was an independent risk factor according to the multivariate logistic regression analysis (OR: 0.45, p < 0.001).ConclusionThe quality of bowel preparations instructed by non-digestive physicians was inferior to digestive physicians, which was a factor potentially associated with poor bowel preparation (ClinicalTrials.gov number: NCT04738578).