Inadequate bowel preparation for colonoscopy can result in missed lesions, aborted or incomplete procedures, and potentially higher complication rates. Although recent studies have shown that split-dose preparations (SDPs) significantly improve bowel cleansing, none has demonstrated the effect of SDPs on other quality markers of colonoscopy.
With this in mind, researchers at Mayo Clinic in Arizona retrospectively compared adenoma detection rates (ADRs), polyp detection rates (PDRs) and colonoscopy completion rates before and after an institutionwide switch to split-dose preparations.
Study leader Suryakanth (Suryakath Reddy) R. Gurudu, M.D., explains, "Until September 2010, we had six or seven prep options, so we restricted choices to one 4-liter dose of GoLytely or a split dose of 2 liters the night before colonoscopy and 2 liters in the morning. Post-implementation, the proportion of patients using split dosing increased from 9 to 74 percent, with excellent overall compliance."
Dr. Gurudu and colleagues then looked at 3,560 patients who underwent colonoscopy the year before split dosing was adopted and 1,615 patients who underwent colonoscopy during the six months after. All outcomes improved in the SDP cohort.
According to study author Francisco C. Ramirez, M.D., one of the main objectives was to see if ADR improved. It did, from 27 to 32 percent. PDR also increased significantly, from 44 to 50 percent. Completion rates — intubation to the cecum — improved from 93.6 percent to 95.5 percent.
"Reaching the cecum is important," Dr. Ramirez says, "but reaching it with a good exam is even more important. In our study, the number of good-to-excellent preps increased from 35 to 54 percent and the number of poor preps decreased."
Dr. Gurudu adds, "We used to see at least one poor prep a day but now we rarely do. When we do, it's usually due to slow motility or some other functional cause. For the average patient, a poor prep is almost nonexistent now. Split dose preps have changed our practice considerably."
"There is overwhelming evidence that the quality of the prep is so much better with split dosing," Dr. Ramirez says. "Although not everyone is doing it yet, many practices are adopting it, and we believe that with all the evidence that has come out, including ours, this will likely become the standard of care."
One of the major patient complaints about drinking 4 liters of PEG is volume, so anything that reduces volume intake is welcome, Dr. Ramirez says.
"Randomized studies have shown that the split dose prep is better tolerated, and anecdotally, we know patients are happier when the dose is split. They're willing to wake up at 4 a.m. to drink the second part, not only because they do better with less volume but also because they know it will lead to a better exam and a greater chance of finding more polyps," he explains.
Mayo researchers are also investigating outcomes when patients take the entire prep the morning of an afternoon colonoscopy.
"We found that quality of the prep was seven times better in patients who took it in the morning than in patients who took it the night before," Dr. Gurudu says. "The more time that elapses between the last liquid intake and colonoscopy, the dirtier the colon becomes. So split-dose regimens and dosing closer to the procedure are clearly the direction things are headed. I don't think we will ever go back."