Only as good as the prep



In the realm of screening routinely offered to our patients in primary care, colon cancer screening stands with cervical cancer screening with a grade A recommendation from the U.S. Preventive Services Task Force. As such, our systems have been set up to gently remind us of colon cancer screening when it is due. If your practice is like mine, it has been almost exclusively colonoscopy. As such, I hear a lot of patient complaints about the colonoscopy prep.

Recently, one of our patients had uncontrolled vomiting with one of the commonly used polyethylene glycol (PEG) 3350 preparations. Many of us may have been aware of the Miralax and Gatorade (M-G) colon prep, and I considered recommending it to my patient. But is it just as good?

Dr. Sameer Siddique of the University of Missouri, Columbia, and colleagues published a systematic review evaluating the comparability of the M-G prep (238-255 g in 1.9 L) to PEG (3.8-4 L) (Am. J. Gastroenterol. 2014;109:1566-74).

The investigators identified five articles and observed that the M-G prep was associated with significantly fewer satisfactory bowel preparations, compared with PEG (odds ratio, 0.65; 95% confidence interval, 0.43-0.98; P = .04). In a subgroup analysis, split-dose M-G was inferior to split-dose PEG in the number of satisfactory preparations.

Patients, however, had a greater willingness to repeat the preparation (OR, 7.32; 95% CI, 4.88-10.98; P <.01). No significant differences were observed with polyp detection or in side effects such as nausea, cramping, or bloating.

The study authors point out that the dose of Miralax in the M-G prep is not FDA approved (because it is 15 times higher than the dose for constipation), and that the solution is hypotonic and can potentially cause hyponatremia. Furthermore, the cost of a colonoscopy ranges from $600 to more than $5,400. At those prices, patient agreeableness to repeat the test does not mean the health care system can bear a deluge of re-do’s.

Remember that split-dose PEG (one half the day before and one half the day of) has been shown to be superior to the night-before preparation, and it can increase tolerability. If a patient has time to get the job done the day of the colonoscopy, maybe this is the way to go.

Dr. Ebbert is professor of medicine, a general internist at the Mayo Clinic in Rochester, Minn., and a diplomate of the American Board of Addiction Medicine. The opinions expressed are those of the author and do not necessarily represent the views and opinions of the Mayo Clinic. The opinions expressed in this article should not be used to diagnose or treat any medical condition, nor should they be used as a substitute for medical advice from a qualified, board-certified practicing clinician.

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