Els van de Vijver

49 children with a discordant result were diagnosed with IBD. Two cases were missed with the calprotectin test (threshold 400 µg/g) and 11 cases were missed with the calgranulin-C test (threshold 0.75 µg/g). Figure 5 I Scatter plot showing concordant and discordant pairs of calprotectin and calgranulin-C measurements. The broken lines represent the ROC-based optimal thresholds for calprotectin (400 µg/g) and calgranulin-C (0.75 µg/g). White fields represent concordant pairs (91%), grey fields represent discordant pairs (9%). DISCUSSION The clinical presentation of paediatric IBD is frequently non-specific and overlaps with irritable bowel syndrome (IBS). Early differentiation is important to avoid delay in proceeding to endoscopy on the one hand and to avoid unnecessary invasive procedures on the other. The mere existence of this trade-off means that a non-invasive and highly discriminative test is needed. We compared the calprotectin and calgranulin-C stool test to see which of the two markers best predicted IBD in children and postulated that the latter probably had better specificity. In this large-scale paediatric diagnostic accuracy study on markers of intestinal inflammation, we show that calgranulin-C has better specificity for IBD than calprotectin, provided the use of common thresholds. When optimal (ROC-based) thresholds are used (i.e. calprotectin 400 µg/g; calgranulin-C 0.75 µg/g), both tests have exceptionally high sensitivity and specificity to diagnose IBD. Head-to-head comparison Calgranulin C and Calprotectin 49