Special preparation diet for colonoscopy (1 day vs 3 days)

In the last quarter of the year it has been published in the journal Gastroenterology and Hepatology, Digestive Endoscopy, the scientific article resulting from a two-year study (2018-2020) comparing one day of low-residue diet for colonoscopy preparation with the usual three-day.

Led by researchers Salvador Machlab, Rafael Campo and Eva Martínez-Bauer, all members of the Digestive Endoscopy Unit of Parc Taulí (doctors and nurses) took part. Pilar López and other professionals from the Technical Screening Office also collaborated.

Then we talk to Dr. Machlab (pictured with Alba Lira, a participating researcher), who will tell us where this study originated, how it has developed, what conclusions they have obtained and what it may lead to in the near future.

The focus of the study is the preparation of the colonoscopy. What does this process consist of?

(Machlab). Preparation for colonoscopy basically involves evacuating the fecal contents of the colon. This allows the scan to be performed safely and to be able to explore the colonic mucosa which is usually the main objective of this scan. It is a pre-procedure act that has a lot of weight on the safety and quality of the scan.

On the other hand, today with the generalization of sedation in endoscopy, the preparation is the biggest drawback for the patient as some studies show.

How does it impact the patient and how important is it?

Preparation guidelines include a restrictive diet and taking a laxative solution for bowel cleansing. This has been evolving over the last 8 years especially in terms of the type of diet and how to take the evacuating solution. Previously a liquid diet was prescribed and currently a low-waste diet also called low-fiber is indicated.

On the other hand, the importance of fiber in intestinal motility and its influence on digestive disorders and other determinants of health is well known. In your day-to-day life as a gastroenterologist, you see how some patients tell you how heavy it is to follow a restrictive diet. This may be of greater relevance in patients and families at increased risk of colon cancer, such as those with familial adenomatous polyposis (PAF) or Lynch syndrome among others, who require monitoring by annual or biannual colonoscopies.

Why did they decide to compare a 3 day vs 1 day prep diet?

In reviewing the new clinical guidelines, Dra. Martínez-Bauer, who leads the high-risk consultation, appreciated that the recommendations given regarding the days of a low-waste diet were of low quality and not very specific. We reviewed the evolution of scientific evidence on this subject and realized that there was much to be done. Virtually all studies compared the liquid diet with different low-diet days, but there were no studies designed to buy low-fiber diet days. It would be a shame to have our patients doing this diet when perhaps it was not necessary, also shortening the diet would allow us to streamline the scheduling of scans and make better use of the gaps in the agenda.

It is also worth mentioning the role that the user experience can play in the performance of the population colon and rectal cancer screening program.

The rate of participation in screening programs influences their effectiveness, so we can expect that facilitating the participation of healthy people in improving the tolerance of the process will improve the performance of colon cancer screening. adds Dr. Machlab

How was the study and what results did they get?

We decided to perform a clinical trial with a non-inferior design and with demanding statistical requirements to obtain the most reliable results possible. The design of non-inferiority is ideal since we did not expect a day of diet to be better than three days, it allows to prove that it is not worse within an acceptable margin. On the other hand, one day of dieting is to be expected to be better tolerated.

For the study we have the participation of 852 volunteers with indication of a colonoscopy for population screening for colon and rectal cancer. They were randomly assigned to follow the standard three-day low-waste diet or the one-day experimental group. On the other hand, there were no other differences in terms of preparation or other factors that could influence them. The assigned group was masked for the research team until statistical analysis. On the day of the endoscopy the nurses of the unit identified these volunteers and made them complete the tolerance surveys and together with the endoscopist the rest of the variables were collected such as colon cleansing for which we use a validated scale and d 'usual clinical use.

The results were pretty good, as we expected, and we were even surprised by some data. The rate of adequate preparations was 97,9% in the one-day diet group versus 96,9% in the 3-day group. Overall the rate of proper preparations is excellent and even the figure is higher in the one day group. On the other hand, we found a higher proportion of participants with excellent preparation in the one-day group and better tolerance was demonstrated.
It should also be noted that there were no differences in quality and performance variables such as scan times, polyp and adenoma detection rate, and complications.

Once the conclusions are drawn, what future lines can this research present?

Following the line of research of my doctoral thesis and after obtaining this data, we will continue to work to improve the tolerance of preparation for colonoscopy that can indirectly further impact the efficiency of the colorectal cancer screening program. Some patients who require periodic endoscopic monitoring have expressed their joy at these results. However, these projects lack funds and institutional support so it is sometimes difficult to continue them. At the moment our scholarship applications were rejected, we managed to complete the study thanks to a donation.

In early 2020 we begin another clinical trial to delve into the role of diet in colon cleansing. Unfortunately the pandemic has negatively influenced the development of the study which is currently on pause and it appears that it will not be able to continue for various reasons. However, we are analyzing the information we have collected and it is proving quite useful to redesign a new study and opt in, hopefully now for more support and funding. At the moment the Spanish Society of Digestive Endoscopy is helping us and we have conversations with the Spanish Association of Gastroenterology to launch a national multicenter clinical trial coordinated from our center.