A pilot study evaluating a new low-volume colon cleansing procedure for capsule colonoscopy

• Introduction
• Materials and methods
• Patients
• Colon preparation procedure
• Colon capsule ingestion
• Standard optical colonoscopy procedure
• Patient follow-up
• Study outcome measures
• Colon cleansing levels
• CCE excretion rates and capsule transit times
• Accuracy parameters and diagnostic yield of capsule colonoscopy
• Statistical analysis
• Results
• Study population
• Colon cleansing levels and capsule colonoscopy completion rates
• Capsule transit times
• Detection of polyps ≥ 6 mm and ≥ 10 mm
• Safety
• Discussion
• References

Background and study aims: Colon capsule endoscopy (CCE) offers an alternative approach for endoscopic visualization of the colon. Some of the current CCE bowel cleansing regimens use sodium phosphate, which has raised safety concerns. Therefore, the aim of the current study was to test the feasibility and efficacy of a new low-volume, sodium phosphate-free polyethylene glycol (PEG) bowel preparation.

Methods: The first 26 patients (original cleansing procedure) received a colon cleansing regimen of PEG plus ascorbic acid: patients drank 1 L in the evening and 0.75 L in the morning before capsule ingestion. Patients also drank an additional 0.5 L PEG boost and an optional 0.25 L PEG boost during the capsule procedure. Following an interim analysis, the cleansing procedure of the subsequent 24 patients was modified, with the morning intake before capsule ingestion being increased to 1 L, as well as the second boost (0.25 L) being administered 1 – 2 hours earlier (modified cleansing procedure).

Results: The overall colon cleanliness was considered to be good or excellent in 83 % (original cleansing procedure) and 82 % (modified cleansing procedure) of patients, without any significant difference between regimens (P > 0.05). In 37 /49 (76 %) of the CCE procedures, the hemorrhoidal plexus was identified and thus the examination was considered complete, with no significant differences between the two CCE cleansing procedures. The capsule sensitivity and specificity for detecting colonic polyps ≥ 6 mm were 91 % (95 %CI 70 % – 98 %) and 94 % (95 %CI 87 % – 97 %), respectively, compared with standard optical colonoscopy.

Conclusion: A colon cleansing procedure using PEG + ascorbic acid for capsule colonoscopy yielded an adequate cleansing level in > 80 % of patients, a completion rate of 76 %, and good accuracy for detecting polyps. This procedure may be considered as an alternative, particularly for patients in whom sodium phosphate-based preparations are contraindicated.

Introduction

The evaluation of individuals with suspected colonic disease includes endoscopic imaging by standard optical colonoscopy and radiological imaging such as air-contrast barium enema, abdominal/pelvic computed tomography (CT), or CT colonography. Colon capsule endoscopy (CCE; PillCam Colon; Given Imaging, Yoqneam, Israel), performed via a device that is swallowed and which contains imagers, light sources, a power source, and a radio-frequency transmitter, offers an alternative approach for endoscopic visualization of the colon [1] [2] [3] [4] [5]. Advantages of CCE include no requirement for conscious sedation, air insufflation, or exposure to radiation. Moreover, CCE is minimally invasive, painless, and the patient may pursue normal daily activities immediately following the procedure. Compared with standard optical colonoscopy, CCE may be more readily accepted by patients, and thereby may improve the willingness to undergo a diagnostic evaluation of the colon and comply with current colorectal cancer screening recommendations [6] [7].

Preparation of the colon prior to CCE differs somewhat from optical colonoscopy because CCE requires not only a clean colon, but the bowel preparation must also promote capsule propulsion through the entire small bowel and colon so as to achieve natural capsule excretion within the battery life of the capsule [1] [2] [3]. Previously reported bowel cleansing modalities for CCE have been complex, using high volumes (4 L) of polyethylene glycol (PEG) solution combined with sodium phosphate boosts and up to 2 L of additional water intake [1] [2] [3]. Sodium phosphate boosts help to promote capsule propulsion through the bowel and augment natural excretion. However, there have been safety concerns over sodium phosphate-based preparations, the most serious being acute phosphate nephropathy, which led the U.S. Food and Drug Administration to issue a warning in December 2008; subsequently the manufacturer recalled its over-the-counter sodium phosphate products [8]. In light of these recent safety concerns surrounding sodium phosphate-based colon preparations, there is a need for an alternative colon cleansing regimen to fill this void. Thus, there are opportunities for improvement, particularly in identifying a lower volume regimen.

In the current prospective pilot study, a new low-volume, PEG + ascorbic acid (sodium phosphate-free) colon preparation procedure was evaluated for colon cleansing quality and CCE excretion/completion rate. Furthermore, CCE was compared with optical colonoscopy for the detection of colonic lesions. Accuracy, completeness of the capsule examination, and safety were also assessed.

Materials and methods

Patients

Patients were between the ages of 18 and 80 years and had suspected or known colonic disease and were referred for standard optical colonoscopy due to rectal bleeding, melena, positive fecal occult blood testing, recent changes in bowel habits, colorectal cancer screening, ulcerative colitis, or positive findings on a gastrointestinal radiographic study.

Patients were excluded if they had dysphagia/swallowing disorder, prior abdominal surgery of the gastrointestinal tract, cardiac pacemaker/implanted electromedical device, magnetic resonance imaging examination scheduled within 7 days after capsule ingestion, patients thought to have a high risk for capsule retention, and pregnant or nursing women [9].

Written informed consent was obtained from each participant, and the study was approved by the institutional review board of each study site.

Colon preparation procedure

This multicenter, prospective pilot study evaluated the effect of a novel, low-volume colon preparation (MoviPrep [Norgine GmbH, Marburg, Germany] with PEG booster) on colon cleansing and on CCE excretion rate. All colon preparation products were “off-the-shelf” products and were used for their exact indication and within the permitted standard doses in accordance with their package inserts. The first 26 patients in the study received a colon cleansing regimen (original cleansing procedure), which included the ingestion of 1 L MoviPrep (PEG + ascorbic acid) in the evening prior to CCE, followed by 0.75 L MoviPrep on the morning of CCE in the clinic. Boosts of additional MoviPrep (0.50 L and 0.25 L) were used along with domperidone and bisacodyl rectal suppository during CCE ([Table 1]). The subsequent 24 patients underwent a modified cleansing procedure. The modified cleansing preparation was instituted after an interim analysis demonstrated suboptimal colon capsule propulsion through the colon when the original cleansing procedure had been used. The modified regimen included the ingestion of 1 L MoviPrep in the evening prior to CCE, followed by an additional 1 L MoviPrep on the morning of CCE. Boosts of additional MoviPrep (0.50 L and 0.25 L) were used along with domperidone and bisacodyl rectal suppository during CCE as per the original regimen, except that the second boost of 0.25 L was given 1 – 2 hours earlier ([Table 1]).

Each patient underwent CCE using the PillCam Colon capsule (Given Imaging). Experience and training are required to accurately interpret capsule endoscopy videos, especially those of the colon [1] [2] [3] [4]. All CCE videos generated in the current study were read and interpreted by blinded physicians who had previous experience with capsule endoscopy of the small bowel. Immediately following CCE, standard optical colonoscopy was performed by a colonoscopist who was blinded to the results of the capsule procedure. CCE findings were compared with those of the optical colonoscopy procedure. In this study, optical colonoscopy served as the reference “gold standard.”

Colon capsule ingestion

CCE was performed in the morning following the described preparation protocol ([Table 1]). Following the intake of 0.5 L of MoviPrep at 10:00 am, each patient was allowed and encouraged to drink water or other clear liquids, such as energy drinks. Patients who did not excrete the capsule by early afternoon were asked to drink an additional 0.25 L of MoviPrep, and also to use a bisacodyl suppository if they did not excrete the capsule by late afternoon.

Standard optical colonoscopy procedure

Approximately 10 – 12 hours after colon capsule ingestion or following capsule exit (whichever came first), the data recorder was removed and the patient underwent optical colonoscopy. Capsules not excreted naturally were removed during colonoscopy. Colonoscopy findings and colon cleansing level were documented.

Patient follow-up

One week (± 24 hours) after the procedures, each patient was contacted and questioned regarding their wellbeing and whether they had any symptoms related to the PillCam Colon procedure or had symptoms that suggested they required an abdominal radiograph to verify capsule exit.

Study outcome measures

Colon cleansing levels

The level of colon cleansing was rated for CCE and for standard optical colonoscopy using the following grading system of a 1 – 4 scale for each segmental section of the colon, as previously reported [1] [2]. Grade 1 (poor) – large amount of fecal residue; Grade 2 (fair) – enough feces or fluid present to prevent a completely reliable examination; Grade 3 (good) – small amounts of feces or dark fluid not interfering with examination; Grade 4 (excellent) – no more than small bits of adherent feces ([Fig. 1]). The primary endpoint was overall rates of good/excellent colon cleansing. The secondary endpoint was to compare the two capsule colonoscopy cleansing preparations (original and modified) in terms of good/excellent cleansing levels (i. e. Grades 3 and 4).

CCE excretion rates and capsule transit times

CCE was considered “complete” when the hemorrhoidal plexus was identified. The proportion of complete procedures out of the total number of procedures was evaluated. Transit time to the colon was measured from the RAPID video for each patient. This was defined a priori as the time from initial ingestion to the time of first colon image. Transit time within the colon was measured from the RAPID video for each patient. The following colon segmental transit times were measured, considering the capsule endoscopic appearance of colonic segments and the localization trace provided by the software: cecum to hepatic flexure; transverse colon; splenic flexure to sigmoid/rectum.

Accuracy parameters and diagnostic yield of capsule colonoscopy

The accuracy parameters of CCE were evaluated and compared with standard colonoscopy (gold standard). The diagnostic yield of CCE was evaluated by the numbers of polyps or masses found compared with the number of pathologies found by the two modalities, i. e. capsule and standard colonoscopy.

Statistical analysis

This was a pilot study in which a total of 50 patients were enrolled. An interim analysis was performed on CCE cleansing level and CCE excretion rate (n = 26). Following the interim analysis results, the colon preparation was modified for the subsequent 24 patients. This study reports the results of all 50 patients.

Descriptive statistics were performed for patient demographics. Proportion tests (unpaired t test) were performed to compare between the two capsule colonoscopy procedures for rate of good and excellent cleansing level (i. e. Grades 3 and 4). A t test for continuous variables was performed to compare between the two cleansing procedures (i. e. original and modified cleansing procedures) for the following parameters:

1. transit time through the gastrointestinal tract – defined as the duration from time of capsule ingestion to capsule excretion

2. transit time through the colon – defined as the time from first capsule image of the cecum to capsule excretion.

The chi-squared test was used to explore whether there was a difference in the excretion rate of CCE (original vs. modified preparation). Accuracy parameters were calculated for detection of patients with polyps in a given size category (defined as a continuous variable) and optical colonoscopy was considered as the gold standard. The true positive results were defined as follows:

1. detection of patients with polyps ≥ 6 mm – defined as a patient who had at least one polyp ≥ 6 mm that was detected by both procedures (i. e. standard optical colonoscopy and CCE) in the same patient.

2. detection of patients with polyps ≥ 10 mm – defined as a patient who had at least one polyp ≥ 10 mm that was detected by both procedures (i. e. standard optical colonoscopy and CCE) in the same patient.

Polyp size of polyps identified by CCE assumed a 50 % margin of error.

Results

Study population

A total of 50 patients were enrolled in the study: 16 patients (32 %) suffered from abdominal pain, 12 (24 %) had personal or family history of colorectal cancer, 7 (14 %) suffered from rectal bleeding (hematochezia) or positive fecal occult blood testing, 5 (10 %) suffered from diarrhea, 3 (6 %) had anemia, 2 (4 %) had a recent change of bowel habits, and 1 patient (2 %) was referred for constipation. It should be noted that some patients had more than one criterion. Of the 50 enrolled patients, 26 underwent the original cleansing procedure and 24 underwent the modified cleansing procedure.

Five patients were excluded from the analysis: one patient failed to complete all of the protocol requirements (i. e. patient consent withdrawn prior to any procedure being performed), two patients experienced a capsule procedure failure (original cleansing procedure), the capsule in one patient remained in the stomach during the entire procedure (modified cleansing procedure), and in another patient it did not progress beyond the cecum (modified cleansing procedure). Therefore, 45 patients (25 female [56 %], 20 male [44 %]) were included in the analysis. The mean age of patients was 55 years (range 28 – 80 years) ([Table 2]).

Colon cleansing levels and capsule colonoscopy completion rates

No significant difference was found between the two CCE cleansing procedures. According to the four-point grading scale, the overall colon cleanliness was considered to be: good or excellent in 83 % (95 % confidence interval [CI] 61 % – 95 %) and 82 % (95 %CI 60 % – 95 %) in the original and modified cleansing procedures, respectively (P = 0.75); fair in 17 % (95 %CI 5 % – 39 %) and 18 % (95 %CI 5 % – 40 %), respectively (P = n.s.); and poor in 0 % in both cohorts (P = n.s.). The results of cleansing level comparison between the two cleansing procedures are presented in [Table 3].

In 37 /49 (76 %) of the CCE procedures, the hemorrhoidal plexus was identified and thus the examination was considered complete. In total, 12 of the procedures were considered to be incomplete, eight following the original procedure and four following the modified procedure. In the original procedure, six capsules (12 %) were delayed in the sigmoid/rectum, one (2 %) in the descending colon, and one (2 %) in the ascending colon. In the modified procedure, two capsules (4 %) were delayed in the sigmoid/rectum, one (2 %) was delayed in the cecum, and one (2 %) was delayed in the stomach. Capsules that were delayed in the colon were retrieved during the colonoscopy procedure, and the capsule that was delayed in the stomach was excreted naturally.

Capsule transit times

There was no statistically significant difference between the two CCE bowel regimens with regard to transit times through the gastrointestinal tract and through the colon. The mean transit time through the gastrointestinal tract for the original and modified procedures were 7:06±2:29 hours and 6:53±2:14 hours, respectively. The mean colonic transit times for the original and modified procedures were 4:08±2:22 hours and 3:34±2:09 hours, respectively (P > 0.05).

Detection of polyps ≥ 6 mm and ≥ 10 mm

CCE demonstrated a high level of accuracy, with a sensitivity and specificity of 91 % (95 %CI 70 % – 98 %) and 94 % (95 %CI 87 % – 97 %), respectively, for detection of polyps ≥ 6 mm, and 100 % (95 %CI 71 % – 100 %) and 92 % (95 %CI 87 % – 92 %), respectively, for the detection of polyps ≥ 10 mm ([Table 4]).

Safety

A total of five adverse events were reported. One severe adverse event during optical colonoscopy was reported due to colon perforation after argon plasma coagulation. There were three mild-to-moderate adverse events due to the bowel preparation prior to CCE, with patients experiencing vomiting and abdominal pain. One mild adverse event was recorded in one patient, who experienced an allergic skin rash due to the capsule adhesive sensors applied to the abdomen.

Discussion

Previously reported bowel cleansing modalities for CCE have been complex, using high volumes of PEG solution combined with sodium phosphate boosts [1] [2] [3]. Although sodium phosphate boosts help to augment the natural excretion of the capsule, there have been significant safety concerns over sodium phosphate-based preparations [8]. Thus, there is a need for a low-volume, non-sodium phosphate-based colon cleansing regimen that adequately cleanses the colon while maintaining a high capsule excretion rate.

The primary objective of this multicenter pilot study was to evaluate the effect of a simplified colon preparation procedure consisting of a single laxative type (PEG) and no sodium phosphate on the colon cleansing level and on the distribution rate of the excreted capsules. To reduce consumption of large volumes of fluid, a solution of PEG with ascorbic acid was used for bowel cleansing and for boosting the capsule through the entire bowel. In a prospective, randomized trial, Ell et al. showed that the combination of ascorbic acid and a PEG-based bowel preparation reduced the volume patients have to drink without compromising efficacy or safety of optical colonoscopy [10]. The low-volume PEG + ascorbic acid preparation was also found to be more acceptable to patients [10]. According to the four-point grading scale used in the present study, the overall colon cleanliness was considered to be good or excellent in 83 % (original cleansing procedure) and 82 % (modified cleansing procedure) of patients. However, cecal and right side colon cleanliness was less than optimal and the capsule excretion/completion rates (76 %) were less than those in previously reported [1] [2] [3] [4] [5] [11] [12]. For example, in a study using a CCE bowel preparation that included pro-kinetic agents and sodium phosphate boosts to facilitate capsule progression and maintain a clean colon, Van Gossum et al. reported good to excellent colon cleanliness in 72 % and a capsule excretion rate of 92.8 % [3]. Spada recently reported on the evaluation of the second-generation colon capsule [11]. The investigators used 4 L PEG (split dose) plus sodium phosphate boosts for capsule propulsion. The overall colon cleansing level was considered “adequate” in 81 % (95 %CI 73 % – 88 %) and the capsule excretion rate was 88 %. A previous meta-analysis by Spada et al. reported data on eight CCE studies including 837 patients, and reported that, overall, good – excellent colon cleanliness was achieved in 77 % (range 27 % – 89 %) and the capsule excretion rate was 87 % (95 %CI 85 % – 90 %) [5]. In a separate meta-analysis, Rokkas et al. reported a capsule excretion rate of 85.3 % but did not report colon cleansing levels [12]. Despite the limitations in capsule excretion rates, CCE in the present study demonstrated a high level of accuracy in detecting patients with polyps ≥ 6 mm (91 % sensitivity and 94 % specificity) as well as in detecting patients with polyps ≥ 10 mm (100 % sensitivity and 92 % specificity).

There are limitations to this pilot study, including a limited number of patients, two separate colon cleansing regimens evaluated due to the original cleansing procedure providing only suboptimal colon capsule propulsion through the colon, and a limited ability to draw statistical conclusions due to the small sample size. Moreover, although there were three study sites, no homogeneity testing across study sites was done, as the sample size was limited and stratifying the data by site and by group would not have permitted firm conclusions to be drawn. Despite these limitations, this was a pilot study that demonstrated the feasibility of using a low-volume PEG + ascorbic acid colon cleansing preparation.

In summary, the study showed that a modified colon cleansing procedure using low-volume PEG + ascorbic acid for capsule colonoscopy yielded adequate results. A cleanliness level of good to excellent could be achieved in > 80 % of patients, showing excellent results in sensitivity and specificity. Although this regimen could be used by all patients, due to the relatively low completion rate (76 %) this new regimen may be targeted to patients in whom sodium phosphate-based preparations are contraindicated, such as patients with inflammatory bowel disease, congestive heart failure, or renal insufficiency/failure. Additional studies involving alternative colon preparations are needed in order to further optimize colon cleanliness for capsule colonoscopy.

Competing interests: None.

• References

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Corresponding author

• References

• 1 Eliakim R, Fireman Z, Gralnek IM et al. Evaluation of the PillCam^® colon capsule in the detection of colonic pathology: results of the first multi-center, prospective, comparative study. Endoscopy 2006; 38: 963-970
  Thieme ConnectPubMedSearch in Google Scholar
• 2 Schoofs N, Devière J, Van Gossum A. Pillcam® colon capsule endoscopy compared with colonoscopy for colorectal diagnosis: a prospective pilot study. Endoscopy 2006; 38: 971-977
  Thieme ConnectPubMedSearch in Google Scholar
• 3 Van Gossum A, Munoz-Navas M, Fernandez-Urien I et al. Capsule endoscopy versus colonoscopy for the detection of polyps and cancer. N Engl J Med 2009; 361: 264-270
  CrossrefPubMedSearch in Google Scholar
• 4 Eliakim R, Yassin K, Niv Y et al. Prospective multicenter performance evaluation of the second-generation colon capsule compared with colonoscopy. Endoscopy 2009; 41: 1026-1031
  Thieme ConnectPubMedSearch in Google Scholar
• 5 Spada C, Hassan C, Marmo R et al. Meta-analysis shows colon capsule endoscopy is effective in detecting colorectal polyps. Clin Gastro Hepatol 2010; 8: 516-522
  CrossrefPubMedSearch in Google Scholar
• 6 Levin B, Lieberman DA, McFarland B et al. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. Gastroenterology 2008; 134: 1570-1595
  CrossrefPubMedSearch in Google Scholar
• 7 Lieberman DA. Clinical practice. Screening for colorectal cancer. N Engl J Med 2009; 361: 1179-1187
  CrossrefPubMedSearch in Google Scholar
• 8 U.S. Food and Drug Administration. Oral sodium phosphate (OSP) products for bowel cleansing (marketed as Visicol and OsmoPrep, and oral sodium phosphate products available without a prescription). FDA alert [12/11/2008]. Available at URL: http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm103354.htm Last accessed: 5 December 2011
  PubMed
• 9 Leighton JA, Rex DK. A grading scale to evaluate colon cleansing for the PillCam COLON capsule: a reliability study. Endoscopy 2011; 43: 123-127
  Thieme ConnectPubMedSearch in Google Scholar
• 10 Ell C, Fischbach W, Bronisch HJ et al. Randomized trial of low-volume PEG solution versus standard PEG + electrolytes for bowel cleansing before colonoscopy. Am J Gastroenterol 2008; 103: 883-893
  CrossrefPubMedSearch in Google Scholar
• 11 Spada C, Hassan C, Munos-Navas M et al. Second-generation colon capsule endoscopy compared with colonoscopy. Gastrointest Endosc 2011; 74: 581-589
  CrossrefPubMedSearch in Google Scholar
• 12 Rokkas T, Papaxoinis K, Triantafyllou K et al. A meta-analysis evaluating the accuracy of colon capsule endopscopy in detecting colon polyps. Gastrointest Endosc 2010; 71: 792-798
  CrossrefPubMedSearch in Google Scholar