Els van de Vijver

102 significant lower exercise capacity, more fatigue and poorer quality of life than IBD- patients with normal parameters. METHODS Patients Patients aged between 8 and 18 years were recruited at the outpatient clinics of five tertiary care centers and six large teaching hospitals in Belgium and the Netherlands. Patients were eligible for inclusion when they had a Paediatric Ulcerative Colitis Activity Index (PUCAI) score below 65 (20) or a Paediatric Crohn’s Disease Activity Index (PCDAI) score below 37.5.(21) Patients were asked to complete two questionnaires, including the PedsQL TM multidimensional fatigue score and the disease specific quality-of-life score IMPACT III, to provide a blood and stool sample, and to perform a 6-minute walking test(6MWT). PedsQL TM Multidimensional Fatigue Scale The PedsQL TM Multidimensional Fatigue Scale consists of a child and parent report and is a commonly used fatigue questionnaire with good reliability.(22) The scale comprises the General Fatigue Scale (GFS, 6 items), Sleep/Rest Fatigue Scale (S/RFS, 6 items), and Cognitive Fatigue Scale (CFS, 6 items).(22) The GFS contains questions regarding the subjective feeling of fatigue and the energy to execute activities, the S/RFS contains questions about the quantity and quality of sleep and rest and the CFS contains questions regarding attention and memory.(23) We used the Dutch version of the Child Self Report, which has been validated for children (8 to 12 years) and adolescents (12 to 18 years).(24) Several studies on fatigue have reported imperfect agreement between child self-reports and parent proxy reports (25) and the child and adolescent self-report questionnaires have a strict factorial invariance across gender and age subpopulations.(26) Participants were asked to rate how often a particular problem occurred in the past month, using a 5- point Likert scale. Scores were transformed on a scale from 0 to 100, in which higher scores indicated fewer symptoms of fatigue. PedsQL TM scores were expressed as z-scores derived from published normative data.(11) Chapter 6 102