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Same-Day Single Dose of 2 Liter Polyethylene Glycol is Not Inferior to The Standard Bowel Preparation Regimen in Low-Risk Patients: A Randomized, Controlled Trial

Kang, Xiaoyu, MD1,8; Zhao, Lina, MD2,8; Zhu, Zhiyong, MD3,8; Leung, Felix, MD4,5; Wang, Limei, MD6; Wang, Xiangping, MD1; Luo, Hui, MD1; Zhang, Linhui, MD1; Dong, Tao, MD1; Li, Pingying, MD3; Chen, Zhangqin, MD6; Ren, Gui, MD1; Jia, Hui, MD1; Guo, Xiaoyang, MD1,7; Pan, Yanglin, MD1; Guo, Xuegang, MD1; Fan, Daiming, MD1

American Journal of Gastroenterology: April 2018 - Volume 113 - Issue 4 - p 601–610
doi: 10.1038/ajg.2018.25

OBJECTIVES: Split dose of 4 l polyethylene glycol (PEG) is currently the standard regimen for bowel preparation (BP). However, it may be unnecessary for patients without high risks (e.g., old age, constipation, and diabetes, and so on) for inadequate BP. The study aimed to compare the efficacy of bowel cleansing between low-risk patients receiving same-day, single dose of low-volume (SSL) PEG vs. standard regimen.

METHODS: This prospective, randomized, observer-blinded, non-inferiority study enrolled low-risk patients in three centers. Patients undergoing colonoscopy were randomized (1:1) to the SSL or standard group. The primary outcome was adequate BP, defined by Boston Bowel Preparation Score (BBPS) ≥6 and each segmental score ≥2. Secondary outcomes included adverse events, cecal intubation rate, and patient willingness to repeat BP, and so on.

RESULTS: Among 2,532 patients eligible for the study, 940 (37.1%) were at low risk and 792 (31.3%) at high risk for inadequate BP. The low-risk patients were randomly allocated to the SSL (n=470) or standard group (n=470). The baseline characteristics of the two groups were similar. Intention-to-treat analysis showed that adequate BP was achieved in 88.1% in the SSL group and 87.0% in the standard group (relative risk (RR) 1.10, 95% confidence interval (CI): 0.75–1.63,P=0.621). The overall BBPS was 7.3±1.2 and 7.3±1.3, respectively (P=0.948). No significant differences were found between the two groups with regards to the right, transverse, and left-segmental colon BBPS (allP>0.05). However, in terms of adverse events, patients in the SSL group reported less nausea (19.6% vs. 29.9%), vomiting (5.3% vs. 11.4%), and abdominal discomfort (2.2% vs. 6.0%) compared with those in the standard group. More patients in the SSL group were willing to repeat BP (94.0% vs. 89.5%,P=0.015).

CONCLUSIONS: For low-risk patients, the SSL regimen was not inferior to the split dose of 4 l PEG for adequacy of BP. Single dose of low-volume regimen had significantly fewer adverse events. This simplified regimen may be preferable in the “easy-to prepare” population.

1State key Laboratory of Cancer Biology, National Clinical Research Center for Digestive Diseases and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, China

2Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, Xian, China

3Department of Gastroenterology, Qinghai Provincial People's Hospital, Xining, China

4Sepulveda ACC, VA Greater Los Angeles Healthcare System, NorthHill, California, USA

5David Geffen School of Medicine at UCLA, Los Angeles, California, USA

6Department of Gastroenterology, Shaanxi Second People's Hospital, Xi'an, China

7Department of Ultrasound, The 305 Hospital of PLA, Beijing, China

Correspondence: Yanglin Pan, MD or Xuegang Guo, MD, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi 710032, China. E-mail: or

8These authors contributed equally to this work.

published online 13 March 2018

SUPPLEMENTARY MATERIAL accompanies this paper at

Received 10 October 2017; accepted 29 December 2017

© The American College of Gastroenterology 2018. All Rights Reserved.
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