Els van de Vijver

12 phase of the disease, what could subsequently alter the course of the disease and prevent long-term complications. In the absence of full curative treatment, the current ultimate goal of paediatric IBD care is to minimize the burden of disease for patients. This thesis focuses on the triage of children with abdominal complaints with regard to endoscopic evaluation, as well as on recognizing fatigue in IBD patients. In the first part of this thesis, we investigate strategies to improve the diagnostic pathway to identify children with gastrointestinal complaints due to IBD for whom endoscopic evaluation is indicated. In the second part, we address quality-of-life issues following the diagnosis of IBD and, more specifically, persistent fatigue in clinically inactive or mild/moderate IBD. Part I - Triage for endoscopy Endoscopy of the upper and lower gastrointestinal tract with biopsies is the reference standard for diagnosing IBD.(1) At the same time however, many patients with gastrointestinal complaints do not appear to have IBD. Since endoscopy is an invasive diagnostic procedure with the possibility of harmful complications, only patients with the highest risk of inflammatory disorders should be exposed to endoscopy. For general paediatricians who see many patients with gastrointestinal complaints (e.g. recurrent abdominal pain, diarrhoea), it may be a challenge to decide which child should be referred for endoscopy. A non-invasive test could enhance the process of triage for children with regard to referral for endoscopy. This triage test could be very helpful if it would be reliable in preventing children at low risk of IBD from undergoing endoscopy. As stated above, IBD is characterized by chronic inflammation of parts of the intestine. For this reason, blood and urine markers have traditionally been assessed as indicators of intestinal inflammation in patients suspected of having IBD.(5) In current practice, C-reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) continue to be the most frequently used blood markers for inflammation. Despite the common use of such blood markers, their specificities and sensitivities for IBD are low, making them less suitable for decision making regarding which patients with gastrointestinal complaints should or should not be referred for endoscopy.(6) Substances that are excreted in urine (e.g. neopterin, Chapter 1