Els van de Vijver

64 Department of Laboratory Medicine of the University Medical Centre Groningen. Immediately after arrival, the faecal calprotectin concentration was measured and the result was made visible to the local clinician by an e-mail notification that included an automated advice on the next best move. Patients with a faecal calprotectin concentration ≥250 µg/g moved on to endoscopy with biopsies (reference standard). Patients with a faecal calprotectin concentration <250 µg/g were re-evaluated at 6 month follow-up after inclusion for possible latent IBD to become visible (alternative reference standard). Deviation from the automated advice on the next best move was considered a protocol violation. The study protocol has been published in BMJ Open.(13) Participants Patients were recruited from paediatric outpatient clinics of sixteen general hospitals and three tertiary care hospitals in the Netherlands and Belgium. The clinicians at the various sites were general paediatricians or paediatric gastroenterologists. Six participating centres had a paediatric endoscopy unit. Patients eligible for inclusion in this ancillary study were aged 6 to 18 years, showing persistent or recurrent non-bloody diarrhoea and abdominal pain. Patients with rectal bleeding or perianal disease were not analysed in this ancillary study, as their symptoms prompted colonoscopy regardless of any biomarker result.(1) Outcome Primary outcome was IBD confirmed by endoscopy of the upper and lower gastrointestinal tract, or IBD ruled out by either endoscopy or uneventful clinical follow- up for 6 months. In case of macroscopic and histological absence of inflammation, imaging of the small intestine was encouraged. Statistical methods Dichotomous data collected at baseline (including presence of chronic non-bloody diarrhoea, weight loss, first degree relatives with IBD and extra-intestinal symptoms) were used to construct a basic logistic regression model to predict the presence of IBD. The incremental value of blood markers (increased C-reactive protein (CRP) and haemoglobin (Hb) below -2 standard deviations) and increased faecal calprotectin (≥250  g/g) were evaluated by adding them to the basic prediction model ( table 1 ). Chapter 4 64