Valoración del papel de la dieta baja en residuos y su duración en la preparación para la colonoscopia

Abstract

Colonoscopy is the primary method for evaluating the colon and rectum. Prior to undergoing this procedure, colon cleansing is necessary, involving primarily a restricted diet for several days and the intake of an evacuating substance. Its diagnostic accuracy is directly influenced by the quality of colon cleansing. Since the inception of colonoscopy, various restrictive diets of different durations have been recommended, but there is no direct scientific evidence proving the utility of these diets nor their optimal duration. In this doctoral thesis, we have evaluated the impact of a low-residue diet on colon cleansing for screening colonoscopy and assessed changes in tolerability and effectiveness, through two non-inferiority randomised clinical trials. In the first clinical trial involving 855 volunteers, we demonstrated the non-inferiority of a single day of a low-residue diet compared to the current standard of 3 days (97. 9% of adequate preparations versus 96. 9%, a difference of 0. 98 [95% one-sided CI 1. 07 p < 0. 001]; δ = -5%), as well as better tolerability (77% versus 60. 9%; p < 0. 001). There were no differences in exploration times nor adenoma detection rates; however, there was a higher proportion of preparations with Boston scores ≥ 8 with 1 day of diet (60. 5% versus 53. 1%; p = 0. 03). In the second clinical trial, we conducted a multicentre, non-inferiority randomised clinical trial involving 582 volunteers. We demonstrated the non-inferiority of a non-restrictive diet (97. 8% of adequate preparations on 1 day of a low-residue diet versus 96. 4%, a difference of 1. 42 [95% one-sided CI 4. 12 p < 0. 01]; δ = 5%). The non-inferiority result was maintained in the 'as treated' analysis, considering the diet recorded in the dietary registry rather than the assigned diet. Additionally, data on better tolerability of the free diet (94. 7% versus 83. 2%; RR 1. 14 [1. 07 - 1. 21]) was found, with no differences in performance in terms of exploration times, aspirated volume, lesion detection rates, nor in the proportion of excellent preparations. These studies included patients at risk of poor preparation, representing approximately 15% of the sample. The studies were conducted following optimal preparation schemes based on the scientific evidence available at the time, with a single evacuating solution in each study, and with a population from the screening programme, limiting the external validity of the studies. In the case of the first study, which demonstrated the non-inferiority of 1 day of a low-residue diet, it has been followed by publications from other groups with heterogeneous samples and guidelines, along with a meta-analysis that validated the results

Date of Award	29 Nov 2024
Original language	Spanish
Supervisor	Rafael Campo Fernandez de los Rios (Director) & Eva Maria Martinez Bauer (Director)