Is a “Good” Colonoscopy Bowel Prep Good Enough? Adenoma Detection Rates from a Randomized Study of Two Colon Cleansing Formulations

Abstract

Purpose: The 2-L polyethylene glycol (PEG) prep was developed to improve pt tolerance for bowel cleansing compared with 4-L solutions. Two 2-L PEG formulations are commercially available: one (HalfLytely®, Braintree Laboratories) combines PEG plus 2 Bisacodyl tablets (PEG+Bis), while the other (MoviPrep®, Salix Pharmaceuticals) combines PEG with ascorbic acid and sodium ascorbate (PEG+Asc). This study compared the effectiveness of these two colon preps. Methods: Pts undergoing colonoscopy (CL) at a single center were randomized to PEG+Asc or PEG+ Bis. The prep was administered according to the manufacturer's instructions. The PEG+Bis prep was begun at noon the day prior to CL when pts ingested 2 Bisacodyl tablets. Once the initial bowel movement occurred or < 6 hrs after consuming the tablets, pts drank 2L of PEG+Bis over 80 mins. The PEG+Asc group consumed 1L of PEG+Asc followed by 500 mL beginning 6pm the evening before the procedure and 1L of PEG+Asc followed by 500 mL starting 6 hrs before the procedure. Four endoscopists, each having an adenoma detection rate > 35%, participated in the study. The primary endpoint was colon-cleansing score, assessed by a blinded investigator using a validated 4-point scale (1=excellent 2=good, 3=fair, and 4=poor). Secondary endpoints included adenoma detection rate. Outcomes were compared using t-tests and chi-square in an intention-to-treat analysis. Results: 52 pts received PEG+Asc and 55 pts received PEG+Bis. The groups were comparable for age, gender, race, weight, and history colon adenomas. Mean colon-cleansing score (±SD) was 1.40±0.69 vs. 1.75±0.70 (P < 0.003) in the PEG+Asc and PEG+Bis groups, respectively. Excellent and good bowel cleansing were recorded in 69% and 23% receiving PEG+Asc vs. 38% and 51% receiving PEG+Bis (P =0.01), with an adequate bowel prep (good or excellent) in a similar proportion of each group. Scope insertion and withdrawal times were similar. Twenty pts (38.5%) in the PEG+Asc group had > 1 adenoma detected vs. 11 pts (20%) in PEG+Bis group (P =0.03). Large adenomas (>10 mm) were found with similar frequency (5.8% vs. 7.2%) in both groups, while smaller adenomas (< 9 mm) were more frequently found in pts receiving PEG+Asc than PEG+Bis (32.7% vs. 12.7%, P = 0.039). Pt compliance and tolerability for the preps were similar. No serious adverse events were reported. Conclusion: 1. PEG+Asc produced superior bowel cleansing compared to PEG+Bis, likely reflecting the benefit of split dosing and/or ascorbic acid. 2. Small and medium-sized adenomas were detected more often in pts receiving PEG+Asc than in pts receiving PEG+Bis. 3. Adenoma detection rates during CL are higher with an “excellent” bowel preparation compared to one that is considered “good.” Disclosure: Dr Cohen - Salix Pharmaceutical - consultant, advisory board, research support, and speaker's bureau. Drs. von Althann, Sanyal, Whitson, Mavronicolas, Burd, Bodian, Bamji, Miller and Aisenberg - none. This Study supported by grant from Salix Pharmaceutical.