While there is little doubt concerning the effectiveness of colonoscopy procedures to detect colon cancer, a new study presented at the American College of Gastroenterology's 74th Annual Scientific Meeting in San Diego places new emphasis on the importance of adequate bowel preparation prior to procedure. The findings come at a time when clinicians are evaluating new bowel preparation solutions to replace the popular over the counter phosphosoda formulations recently withdrawn from the market.
In a retrospective study performed at the VA Medical Center in Phoenix, AZ, Dr. Nooman Gilani, Dr. Veronika Karasek and their team evaluated the impact of inadequate bowel preparation on the follow-up interval recommended by the endoscopist. After studying records on some 788 patients, the researchers concluded that inadequate bowel preparation by the patient before the procedure resulted in a recommended follow-up colonoscopy 17.1 months earlier than average. By comparison, finding an adenoma during the procedure resulted in a recommended follow-up examination 17.2 months earlier than average.
"Endoscopists' ability to detect colonic legions, especially the flat or depressed ones, is greatly linked to the quality of bowel preparation. For years, we have emphasized the importance of adequate bowel preparation for patients to help ensure the detection of adenomas during colonoscopy, especially on the right side of the colon," explains Dr. Karasek. "This new finding suggests that endoscopists are taking into consideration the quality of preparation when recommending a follow-up interval, regardless of the findings of the examination.
"Emphasizing better bowel preparation, and making it easier and more palatable for patients, may not only make colonoscopy less intimidating, for some it may mean an extra year and a half between follow-up procedures."
Researchers Evaluate New Bowel Prep Approaches
As gastroenterologists consider the importance of bowel preparation, they are also evaluating new formulations of bowel preparation products for their patients. In December 2008, a popular OTC bowel preparation for colonoscopy, which contained phosphosoda, was recalled from the market. Researchers at the American College of Gastroenterology presented papers evaluating new bowel preparation formulations and approaches.
In a pilot study led by Dr. Ron Palmon at the Mt Sinai School of Medicine, researchers evaluated the safety and efficacy of Polyethelne Glycol (PEG) plus ascorbic acid (Moviprep) compared to magnesium citrate for bowel preparation before colonoscopy. The randomized study included 90 patients and found that overall colon preparation was excellent or good for 92% of those receiving the PEG and ascorbic acid solution, as well as 86% of those receiving the magnesium citrate formulation. Sixty-two percent of the patients given the PEG and ascorbic acid formulation indicated that it was easy to fairly easy to take, compared to 82% of those given the magnesium citrate formulation. The study also showed a significant improvement in the quality of bowel preparation when using split dosing with either preparation. Split-dosing involves doses given both the night before a procedure and a few hours prior - vs. traditional dosing, given the day before.
"Both PEG with ascorbic acid and magnesium citrate provided good to excellent colon cleansing in almost all the patients we evaluated," explained Dr. Palmon. "The fact that patients were, for the most part, able to tolerate these products and found them relatively easy to administer suggests that they may be an alternative to phosphosoda. Regardless of which formulation a clinician chooses to recommend, we must all reinforce how vital proper procedure preparation is to colonoscopy."
Exploring the Proximal Colon
In a second study presented at the conference, Dr. Douglas Rex of Indiana University, and a team of researchers evaluated a new oral sulfate solution's ability to cleanse the proximal, or right colon, which has received increased attention as an important site of missed adenomas. In the study, the new oral sulfate solution (SUPREP®) was compared to a large volume polyethylene glycol (PEG) and electrolytes solution (NuLYTELY®) among 130 patients.
The researchers found significant differences in both the quality of the preparations, and how well patients were able to complete the preparations. In each case, the oral sulfate solution outperformed the PEG and electrolytes solution. Specifically, 100% of patients were able to complete the split dose oral sulfate solution, compared to only 91% who completed the PEG and electrolytes solution. Investigators performing colonoscopies scored 71% of the oral sulfate preparations as excellent, compared to only 34% of the PEG and electrolyte solution.
"High volume preparations require patients to consume up to four liters of liquid, which can be daunting," said lead researcher Dr. Rex. "The oral sulfate solution provides a successful route to reduce the volume of bowel preparation that patients need to drink for colonoscopy."
Source: American College of Gastroenterology
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