Els van de Vijver

62 ABSTRACT OBJECTIVE: We evaluated four diagnostic strategies to predict the presence of inflammatory bowel disease (IBD) in children who present with chronic non-bloody diarrhoea and abdominal pain. METHODS: We conducted a prospective cohort study, including 193 patients aged 6–18 years, who underwent a standardised diagnostic work-up in secondary or tertiary care hospitals. Each patient was assessed for symptoms, c-reactive protein (>10 mg/L), haemoglobin (<-2 SD for age and gender) and faecal calprotectin (≥250  g/g). Patients with rectal bleeding or perianal disease were excluded because the presence of these findings prompted endoscopy regardless of their biomarkers. Primary outcome was IBD confirmed by endoscopy, or IBD ruled out by endoscopy or uneventful clinical follow-up for 6 months. We measured the predictive performance of each strategy with AUC and decision curves. RESULTS: 22 of 193 (11%) children had IBD. The basic prediction model was based on symptoms only. Adding blood or stool markers increased the AUC from 0.718 [95%CI: 0.604- 0.832] to 0.930 [95%CI: 0.884-0.977] and 0.967 [95%CI: 0.945-0.990]. Combining symptoms with blood and stool markers outperformed all other strategies (AUC 0.997 [95%CI: 0.993- 1.000]). Triaging with a strategy that involves symptoms, blood markers and calprotectin will result in 14 of 100 patients being exposed to endoscopy. Three of them will not have IBD, and no IBD-affected child will be missed. CONCLUSION: Evaluating symptoms plus blood and stool markers in patients with non-bloody diarrhoea is the optimal test strategy that allows paediatricians to reserve a diagnostic endoscopy for children at high-risk for IBD. Chapter 4