In order to make meaningful therapy decisions for patients with IBD, regular assessment
of the extent of intestinal inflammation is necessary. This is particularly true for
patients with Crohn's disease, as the inflammatory activity often does not correspond
adequately to the symptoms described by the patient. Therefore, inflammatory activity is
assessed not only at the time of diagnosis and during follow-up based on history,
physical examination, and laboratory tests, but also through regular endoscopic
examinations. The available endoscopic scores for assessing IBD were developed and
validated based on the standard light setting, known as White Light Endoscopy (WLE).
However, there is inadequate correlation between these scores and the most commonly used
histological IBD scores. In recent years, in addition to WLE, other endoscopy modes
developed for image optimization have been used for macroscopic assessment of IBD. An
example of a new image-enhancing endoscopy mode is Texture and Color Enhancement Imaging
(TXI; Olympus Corporation, Tokyo, Japan). The TXI mode is a directly switchable image
mode on the endoscope, so it can be performed without special preparation or staining of
the intestinal mucosa. Only the generated endoscopy image is digitally processed. With
this endoscopy module, brightness in dark areas of an endoscopic image is selectively
increased, color and surface structure are improved, making subtle tissue differences
such as minor color changes more visible. There are only limited data on the use of the
TXI mode for endoscopic assessment of the intestinal mucosa in patients with IBD. Only a
single-center study has been conducted, which included 146 patients with ulcerative
colitis, aiming to evaluate the presence of mucosal healing using WLE and TXI. In this
study, the TXI mode appeared to be superior to WLE in detecting inflammatory lesions.
Since an endoscopy score (so-called TXI score) that has not yet been validated in larger
cohorts was used in this study, comparability between WLE and TXI has not been
established. Therefore, the present project hypothesizes that predicting inflammatory
activity at the histological level using the TXI mode is at least as good as using
conventional WLE. Crucially, the same endoscopic score is used for both modes (TXI and
WLE). Successful implementation of this research question could improve the diagnosis and
monitoring of IBD patients. Moreover, if the TXI mode proves superior to WLE, it could
lead to a reduction in the number of intestinal biopsies required for diagnosis,
resulting in significant savings in personnel and financial resources.
The aim of the study COLORIZE is to assess the non-inferiority of TXI compared to WLE in
predicting histological changes in IBD using the area under the curve (AUC) as a measure
of prognostic accuracy. The hypothesis to be tested in this study is: There is no
difference in the assessment of inflammatory activity in the colon and terminal ileum in
chronic inflammatory bowel diseases (CED) between the TXI mode and White Light Endoscopy
(WLE) when the AUC of the TXI mode (AUC_TXI) is less than the AUC of WLE (AUC_WLE) minus
the non-inferiority margin δ. The null hypothesis H0 states: AUC_TXI < AUC_WLE - δ,
while the alternative hypothesis H1 states that AUC_TXI ≥ AUC_WLE - δ.
A prospective, crossover study is being conducted. A total of 80 patients diagnosed with
chronic inflammatory bowel disease and scheduled for outpatient ileocolonoscopy are
included. After the legally required informed consent process, participating patients are
asked to undertake the necessary preparation or bowel cleansing measures at home for the
ileocolonoscopy.
The study consists of four parts:
Part 1: Before the start of the endoscopic examination, the patient's medical IBD
therapy (current therapy and therapy of the past 12 months), current GI symptoms, and any
previous GI surgeries are recorded and documented in writing using a patient
questionnaire. Subsequently, an ileocolonoscopy is performed. During the withdrawal of
the endoscope, the intestinal mucosa (mucosa) is assessed using the endoscopic light
settings WLE and TXI. The macroscopic assessment includes the following five Regions of
Interest (ROI): terminal or neo-terminal ileum, ascending colon, transverse colon,
descending colon/sigmoid, rectum. One biopsy taken in all five ROI, and if necessary,
additional biopsies are taken from macroscopically inflamed mucosa regardless of the ROI.
Photodocumentation is performed during the examination (During the examination, at least
three photos are saved per ROI, consisting of an overview photo in WLE, WLE close (close
means closer to the intestinal mucosa) and TXI close). With the exception of the TXI
photos, this corresponds to the standard procedure of "step biopsies" in IBD.
Part 2: Endoscopic scores (MES for ulcerative colitis, SES-CD for Crohn's disease)
are determined for WLE and separately for TXI based on the photodocumentation taken
during the ileocolonoscopy. Endoscopic scoring based on WLE is done by unblinded assessor
1 immediately after the examination. After completion of all ileocolonoscopies (n = 80),
the entire stored image material (WLE and TXI) is re-evaluated by seven examiners, three
of whom had performed a part of the ileocolonoscopies. The inflammatory activity should
be assessed per photo on a scale of "inactive, mild, moderate and severe". The endoscopy
photos are presented free of patient data and in random order to avoid recognition of the
examinations performed by the examiners themselves.
Part 3: Pathologists at the University Hospital Ulm determine histological scores based
on the collected intestinal biopsies (Geboes for ulcerative colitis, GHAS for Crohn's
disease).
Part 4: The prognostic quality of TXI vs. WLE is tested using ROC curves, initially
binary (inflammation vs. no inflammation). In secondary analyses, the degree of
inflammation is also taken into account according to the scores obtained. The
histological score is used as the gold standard.
Extended patient follow-up beyond the ileocolonoscopy procedure with biopsy collection is
not necessary beyond the standard follow-up for a routine ileocolonoscopy.