Comparison of Four Different Colonic Preps in 3595 Patients at A University Center: A Real Life Experience

Tilak R Baba, James H. Lewis

Tilak R Baba, Department of Internal Medicine, Georgetown University Medical Center, Washington DC, the United States
James H. Lewis, Division of Gastroenterology, Department of Medicine, Georgetown University Medical Center, Washington DC, the United States

Correspondence to: Tilak R Baba, MD, Department of Internal Medicine, Pasquerilla Healthcare Center, 5th Floor 3800 Reservoir Road, N.W., Washington D.C. 20007, the United States.
Email: tilak.r.baba@gunet.georgetown.edu
Telephone: +1-919-475-7172
Received: May 10, 2016
Revised: June 2, 2016
Accepted: June 5, 2016
Published online: June 21, 2016


AIM: Several bowel preps are currently used for colonoscopy but only limited data are available comparing the different products.

METHODS: We retrospectively reviewed all colonoscopies performed at Georgetown U. Hospital from May 2013 to May 2014. A 9-point modified Boston Bowel Preparation Scale (BBPS) was utilized (best score = 9) by experienced endoscopists. Colonoscopies without a BBPS score were excluded.

RESULTS: Four preps and their percentage usage were 4-L PEG solutions (Golytely® or Colyte®) (50%), PEG with bisacodyl tablets (Miralax®) (17%), PEG with ascorbic acid (Moviprep®) (8%), sodium picosulfate (Prepopik®) (25%), with the following overall BBPS scores respectively: 7.45, 7.45, 7.40, 7.55. Statistical superiority of split-doseto day-prior dose was seen for Golytely®/Colyte®, Miralax®, and Moviprep® with a trend seen for Prepopik®. Comparison of each prep by split and prior day dosing showed a significantly higher score only for Golytely®/Colyte® and Prepopik® vs Moviprep® given prior day dosing. A higher BBPS score was seen for women vs men overall for both split-dose and day-prior dosepreps (with the exception of Moviprep® in PD preps). Higher scores were seen for a.m. procedures but were not significant. All preps had lower scores in the right colon, regardless of being split-dose or day-prior dose.

CONCLUSIONS: This real world experience in nearly 3600 patients confirms that split dosing is superior to day-prior dosing. We found women had higher BBPS scores than men but no differences were seen between morning and afternoon procedures. All preps were relatively comparable, however differences in price may be an important decision-maker.

Key words: Colonoscopy; Colon preparations; BBPS; Polyethylene Glycol; Miralax; Ascorbic Acid; Sodium Picosulfate

© 2016 The Authors. Published by ACT Publishing Group Ltd.

Baba TR, Lewis JH. Comparison of Four Different Colonic Preps in 3595 Patients at A University Center: A Real Life Experience. Journal of Gastroenterology and Hepatology Research 2016; 5(3): 2077-2081 Available from: URL: http: //www.ghrnet.org/index.php/joghr/article/view/1750


Inadequate bowel preparation is related to lower adenoma detection rates, longer procedural times and an increase in costs and need for repeat exams[1-5]. Various bowel regimens are commercially available for pre-colonoscopy preparations[6] and each has been studied for its efficacy and tolerability. Bowel regimens are generally categorized based on their ingredients such as, PEG-based, sodium phosphate, and sodium picosulfate solutions[6]. Several studies have compared two bowel regimens within each class[7-9]. However, there are limited data comparing multiple regimens across different classes of bowel preparations. The timing of the bowel preparation has also been shown to play an important role in increasing effectiveness[10,11]. Six organizations have issued guidelines that endorse split-dose (SD) over day-prior dose (DPD) regimen[6,12-16]. Patient satisfaction and compliance have also been shown to be superior with SD compared to DPD preparations[10,17,18].

The aim of this study was to evaluate the effectiveness of the four most commonly used bowel preparations in our tertiary center endoscopy unit to determine whether any differences exist between the preps and whether there was a correlation between split dosing or day-prior dosing and the effectiveness of the bowel preparation in a non-study setting.


We conducted a retrospective cross-sectional review of all inpatient and outpatient colonoscopies performed at Georgetown University Hospital from May 2013 to May 2014. Data were collected for patients ≥ 18 years of age, with the only exclusion being if no bowel preparation score was recorded in our electronic endoscopic database (EndoPro®, Pentax Corporation, New Jersey). The bowel preparation was chosen at the discretion of the endoscopist. Based on our standard information for patients about prepping for colonoscopy, patients were instructed to take the first half of a SD regimen starting in theevening prior to the procedure and the second half of the prep was taken 6-9 hours prior to the colonoscopy. For DPD dosing, patients were instructed to take the whole prep during the late afternoon or evening prior to their procedure. All patients were instructed to drink only clear liquids the entire day before the procedure. The 9-point modified Boston Bowel Prep Scale (BBPS)[19], as recorded in our electronic endoscopy database, was used to evaluate effectiveness in each part of the colon (left, transverse, right) using a scale of 1 to 3 as follows: 1 = residual stool/mucosa not well seen; 2 = stool fragments but mucosa well seen; 3 = no stool present (maximum score = 9). A score of zero in the original BBPS was considered equivalent to one. Scores were based on the mucosal appearance prior to any washing or aspiration maneuvers. Additionally, the following data were collected: age, sex, race, split-dose versus day-prior dose prep, morning (AM) versus afternoon (PM) procedure times. The primary end point was total BBPS score. Secondary end point was BBPS score according to each part of the colon. Statistical significance was calculated using an unpaired t-test. All calculations were made using Microsoft Excel®. The study was approved by the Institutional Review Board of Georgetown University Medical Center.


The total number of colonoscopies performed in this one year period was 4046 with 451 colonoscopies (11.1%) excluded as no bowel prep name or BBPS score was recorded. Table 1 shows the baseline patient characteristics of the four most commonly used bowel preparations at our institution: 4-L polyethylene glycol-electrolyte lavage solution (PEG-ELS) (either GoLYTELY®[Braintree Laboratories, Braintree MA] or CoLyte® [MedaPharma, Somerset NJ]), 2-L PEG solution with bisacodyl delayed release tablets (PEG) (MiraLAX®, Germany), 2-L PEG with ascorbic acid (PEG-A) (MoviPrep®, Salix Pharmaceuticals, Raleigh, NC), and sodium picosulfate based solution (PICO) (Prepopik®, Parsippany NJ). Bowel preparations other than the ones listed above were rarely used and not included in this analysis. For the purposes of this analysis, the results of GoLYTELY® and CoLyte® were combined as one class. MiraLAX was instructed to take with Gatorade 64oz or an equal amount of water (2 liters) at the patient’s discretion.

Themean age of patients for each group was over 50. The racial makeup reflected the patient population at our medical center. Overall, approximately 55% of the procedures were done in the morning (prior to 12 noon). Table 2 lists the individual BBPS scores for each of the four preparations studied. The majority of subjects, both overall and within each preparation group, had BBPS scores of 7 or above. The overall BBPS scoresof the individualbowel prepswere as follows: PEG-ELS (7.45), PEG (7.45), PEG-A (7.40), PICO (7.55) (p-value 0.351).

Table 3 compares pre-cleaningBBPS scores between each of the preps by split-doseand day-priordosing. All of the BBPS scores were comparable with no statistically significant difference except for PEG-A, which had a numerically lower score than the other three preps for day-priordosing. However, this difference was not seen for the split-doseregimen for PEG-A.

When comparing splitvs day-prior dosing for each preparation, SD was significantly better than DPD, except for PICO, which had similar scores for both split and day-prior dosing as illustrated graphically in Figure 1.

The timing of the colonoscopy (AM or PM) did not appear to be an important factor in achieving an adequate bowel preparation for any of the regimens, except PEG-ELS, which had a lower score for PM procedures in patients given day-prior dosing(6.95 vs 7.23, p-value 0.025) (Figure 2).

Figure 3 illustrates the differences in BBPS scores comparing women to men based on each preparation. Women had a better bowel prep score than men for all regimens except for PEG, which showed a trend toward a better BBPS score for women, but was not statistically significant.


Various bowel regimens are currently available for colonoscopy preparation. Our retrospective review of the four most widely used bowel preparation regimens in our endoscopy unit revealed that there were no significant differences between the preps based on our modified BBPS score. All physicians were trained in using the score, which is part of the endoscopy report. Since the scoring was not part of the study, responses were not controlled but reflect real-life results. While there have been studies comparing two different preps, there are limited data comparing PEG, PEG-ELS, PEG-A and PICO to one another. Both GoLYTELY® and CoLyte® are 4-L PEG solution whereas MiraLAX® and MoviPrep® are low-volume 2-L regimens. Prior randomized controlled trials have shown comparable results between 4-L PEG based solutions and the 2-L PEG solution with ascorbic acid (PEG-A)[7-9]. While these studies used different 4-L PEG-electrolyte solutions, they were similar to the PEG-ELS preparations used in our study. These studies also used different bowel cleansing visualization scales (inverted Ottawa Scale, independent rating scale, Residual Stool Score). However the BBPS records similar data. Our results with the BBPS show a statistically significantly lower preparation score with PEG-A when compared to each of the other three preparations given as DPD. However, this difference was not seen for theSD regimen of PEG-Aand the clinical relevance of a slightly lower score is lessened given that the endoscopist can deal with residual stool at the time of the procedure.

Prior studies also have compared 4-L PEG solutions (PEG-ELS) with 2-L PEG solutions and bisacodyl tablets (PEG) and found no significant differences in bowel preparation effectiveness using the BBPS scale[20,21]. However, one randomized trial, and a recent meta-analysis of PEG bowel preparations, demonstrated statistically significantly fewer satisfactory bowel preparation scores as compared to PEG-ELS solutions using either the BBPS or Ottawa Preparation Scale (OPS)[22,23]. This difference was not evident in our analysis, as PEG was comparable to not only PEG-ELS but also to PEG-A and PICO.

Several studies, including a recent meta-analysis, have shown SD is better than DPD regimen[7,10,11,24] and current colonoscopy guidelines recommend the split dosing regimen[13-15]. Our data reflect those findings, as SD was superior across all preparations except for PICO. This particular finding however, was in contrast to information reported in the recently published USMSTF guidelines[16]. However, our results for PICO could be confounded because of the relatively small sample size of the DPD regimen (6% of all PICO preparations). Prior studies on PICO have shown non-inferiority to PEG based solutions (HalfLytely®, colonLytely®) and/or sodium sulfate with DPD[25-27]. However, a single-blinded randomized controlled trial suggested a split dose regimen is better than the traditional prior day dosing of sodium picosulfate (Pico-Salax®)[28]. These conflicting results warrant further evaluation of the optimal dosing regimen for PICO.

While our results suggested no important difference in overall BBPS scores between the preps studied, we did not collect data on patient satisfaction or compliance with each of the regimens. Previous studies have demonstrated differences in patient preference for one preparation over another (e.g. PEG over PEG-ELS)[22,29,30]. However, there is not enough data to draw such conclusions regarding sodium picosulfate based preparations (such as PICO). Nevertheless, several studies have indicated a patient preference forthe reduced (2-liter) volume PEG solutions (PEG, PEG-A) over traditional 4-liter PEG solutions (PEG-ELS)[8,9].

Our results also indicated that the BBPS scores did not differ significantly based on the timing of the procedure (morning vs afternoon) with the exception of PEG-ELS given as day-prior dosing. A recent prospective study of 300 outpatient colonoscopies found that the timing of colonoscopies did not have a significant impact on the quality of the bowel preparation[31]. However, that study did suggest a better quality of the bowel preparation was found in patients with a shorter time between finishing the bowel prep and the start of colonoscopy. Similar results were found in another prospective study of 378 patients[32], but these investigators did not use a validated scale to assess the quality of bowel preparation. Nevertheless, it appears that a shorter “runway” time between finishing the prep and undergoing colonoscopy is associated with a better quality preparation[33]. This conclusion was also drawn in a study that suggested same day preparation for afternoon colonoscopy have better results than prior-day preparation[34].

Finally, our analyses demonstrate that women had statistically significantly higher BBPS scores than men across all preps except for PEG. No prior studies have specifically evaluated this potential gender-specific finding. It is possible that women have higher adherence rates to preparation instructions, which, if confirmed, would suggest the need for increased patient education geared towards men.

Our study had a number of potential limitations. It was a retrospective review of colonoscopies, andthe fact that bowel preparations were selected at the discretion of the endoscopists, resulted in uneven sample sizes among the different groups. The lack of patient satisfaction data limits our ability to assess compliance, which may have contributed to the effectiveness of each of the bowel preparations[10,17,35-37]. Nevertheless, this real-world experience of bowel preps for colonoscopy in nearly 3,600 patients confirms that split dosing is superior to prior day dosing. While we found that women had higher BBPS scores than men, no differences were seen between the qualities of the preps when morning procedures were compared to those performed in the afternoon.

Importantly, the retail prices for the bowel preps analyzed based on the cost in our outpatient hospital pharmacy were as follows: GoLYTELY® $20; CoLyte® unflavored $36, MiraLAX® $4 per 17 g, MoviPrep® $74, and Prepopik® $79. These differences in price with relative comparable effectiveness of the different preps suggest that cost may play an important role in prescribing one preparation over another.


Guarantor of the article: James H. Lewis, MD, FACP, AGAF, FACG.

Specific Author Contributions: Conception and Design: James H. Lewis and Tilak Baba; acquisition of data: Tilak Baba; analysis and interpretation of data: James H. Lewis and Tilak Baba; drafting of the manuscript: James H. Lewis and Tilak Baba; statistical expertise: Tilak Baba; overall supervision of the project: James H. Lewis.

We thank the staff of endoscopy suite at Georgetown University Hospital for their help in initiating the research project.

Our research was presented in part at the American College of Gastroenterology 2014 Annual Scientific Meeting in Philadelphia, PA.


There are no conflicts of interest with regard to the present study.


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Peer reviewers: Francis Seow-Choen, Professor, Director, Seow-Choen Colorectal Centre, 290 Orchard Road. Paragon #06-06 Singapore; Hirotada Akiho, MD, PhD, Department of Gastroenterology, Kitakyushu Municipal Medical Center 2-1-1, Bashaku, kokurakita-ku, Kitakyushu-shi, Fukuoka 802-0077, Japan.


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