Els van de Vijver

68 Table 2: Baseline characteristics of 193 patients Characteristics IBD (n=22) non-IBD (n=171) p-value Demographics Median (IQR) age in years 14 (8-17) 12(6-17) Male gender 9 (41%) 98 (57%) Symptoms Persistent non-bloody diarrhoea (>4 weeks) 15 (68%) 58 (34%) 0.004 Recurrent non-bloody diarrhoea and abdominal pain 15 (68%) 149 (87%) 0.043 Unintended weight loss 10 (46%) 48 (28%) 0.154 First degree relative with IBD 1 (5%) 17 (10%) 0.667 Extra-intestinal symptoms 3 (14%) 11 (6%) 0.430 Blood markers Increased C-reactive protein 13 (59%) 9 (5%) <0.001 Anaemia 15 (68%) 14 (8%) <0.001 Stool markers Faecal calprotectin ≥250  g/g 22 (100%) 18 (11%) <0.001 Data are number (%) of patients unless stated otherwise. Abbreviations: IQR, inter quartile range; SD, standard deviation Area under the receiver-operating-characteristics curve (AUC) Receiver-operating-characteristics (ROC) curve analysis revealed an AUC of 0.718 [95% CI: 0.604-0.832] for the basic model to predict IBD. In comparison, the ROC curve analyses of strategy 2 (symptoms + blood markers), strategy 3 (symptoms + calprotectin) and strategy 4 (symptoms + blood markers + calprotectin) revealed AUCs of 0.930 [95% CI: 0.884- 0.977], 0.967 [95%CI: 0.945-0.990] and 0.997 [95%CI: 0.993-1.000], respectively ( Figure 2 ). Chapter 4 68