Els van de Vijver

38 ABSTRACT BACKGROUND: Calgranulin-C (S100A12) is a new faecal marker of inflammation that is potentially more specific for inflammatory bowel disease (IBD) than calprotectin, since it is only released by activated granulocytes. We compared calgranulin-C and calprotectin to see which of the two tests best predicted IBD in children with chronic abdominal pain and diarrhoea. METHODS : DESIGN: Delayed-type cross-sectional diagnostic study. SETTING AND PATIENTS: Previously undiagnosed patients aged 6 to 17 years, who were seen in paediatric clinics in the Netherlands and Belgium, sent in a stool sample for analysis. Patients with a high likelihood of IBD underwent upper and lower endoscopy (i.e. preferred reference test), while those with a low likelihood were followed for 6 months for latent IBD to become visible (i.e. alternative reference test). We used Bayesian modeling to correct for differential verification bias. MAIN OUTCOME MEASURES: Primary outcome was the specificity for IBD using predefined test thresholds (calgranulin-C 0.75 μg/g, calprotectin 50 μg/g). Secondary outcome was the test accuracy with thresholds based on receiver operating characteristics (ROC) analysis. RESULTS: IBD was diagnosed in 93 of 337 patients. Calgranulin-C had significantly better specificity than calprotectin when predefined thresholds were used (resp. 97% [95% CI 94- 99%] vs. 71% [95% CI 63-79%]). When ROC-based thresholds were used (calgranulin-C 0.75 µg/g, calprotectin 400 µg/g), both tests performed equally well (specificity 97% [95% CI 94- 99] vs. 98% [95% CI 95-100%]). CONCLUSIONS: Both calgranulin-C and calprotectin have excellent test characteristics to predict IBD and justify endoscopy. Chapter 3