Trans-abdominal ultrasound as a point-of-care test for the assessment of disease activity in patients with ulcerative colitis

In recent years, it has been shown that mucosal healing is associated with
better outcomes in patients with inflammatory bowel disease (IBD). However,
repeated assessment of the mucosa currently requires multiple endoscopies which
creates logistic and economic problems as well as a considerable burden for the
patient. Therefore, alternative tools to assess luminal disease activity in IBD
patients are needed. Chemical assays such as the measurement of faecal
calprotectin and serum C-reactive protein, albumin and platelet counts have
been evaluated but these test are hampered by significant errors and
unreliability. It has been reported that trans-abdominal ultrasound is useful
for the detection and follow-up of patients with IBD and that this imaging
technique can be applied to determine the extent and location of inflammation.
However, only a few studies have been performed that compare trans-abdominal
ultrasound with endoscopy for the assessment of mucosal disease activity and
prospective studies in which treatment decisions are made based on ultrasound
appearance are also limited. The aim of the proposed study is to develop and
validate an ultrasound activity index for the assessment of mucosal disease
activity in patients with ulcerative colitis (UC), compared to endoscopy as the
reference (*gold*) standard. In a later phase, this activity index will be
validated for the assessment of treatment effect.

The primary objective of this study is to develop an ultrasound-based activity
index with appropriate cut-off values that can be used as a point-of-care test
for the assessment of mucosal disease activity in UC patients. Secondary
objectives of this study are to assess the relative importance of individual
ultrasound parameters and patient satisfaction. Lastly, a cost-benefit analysis
will be performed.

Observational cross-sectional study. In the second phase the activity index
will be validated prospectively by monitoring treatment effect (not described
in this protocol).

Blood will be drawn once in order to measure various inflammatory markers as
part of standard care. Patients will be subjected to two non-invasive
trans-abdominal ultrasound examinations and one colonoscopy or sigmoïdoscopy.
Only patients who need to undergo endoscopy in the frame of their usual care
will be included. Trans-abdominal ultrasound is a safe procedure that uses high
frequency sound waves for the visualization of internal organs. Another
advantage of ultrasound is the fact that it is inexpensive compared to other
techniques, such as endoscopy or Magnetic Resonance Imaging (MRI). Endoscopy is
a relative safe procedure. The two most common complications of colonoscopy are
bleeding and perforation (0,2 %, 0,1 %). Implementation of trans-abdominal
ultra sound as a point-of-care test for the assessment of disease activity in
UC patients may result in a reduced need for colonoscopy and MRI, thereby
reducing costs and the burden for patients. Waiting times for MRI and
colonoscopy are also long whereas ultrasound can be applied on a more regular
basis. Treatment decisions based on ultrasound appearance can therefore be made
*on the spot*, allowing for a point-of-care approach in these patients.