Els van de Vijver

119 Comparison of FC test accuracy per manufacturer At present, most clinical practitioners have access to one or more faecal calprotectin tests, but these tests are neither standardized nor harmonized. We nevertheless feel that our findings can be extrapolated to settings with calprotectin tests from different manufacturers, as they fairly agree in the lower range (below 250 µg/g).(11) Above this cut-off point however, inter-assay variability is considerable. On the other hand, tests with a limited measuring range (say 50 to 300 µg/g) are considered unsuitable for triaging for endoscopy. In the absence of assay standardisation, more assay-specific cut-offs are needed. Cost efficiency Yang et al. performed a cost-effectiveness analysis comparing FC as triage for endoscopy with direct endoscopic evaluation alone in the United States.(12) They showed that cost- effectiveness of FC screening varied with the pre-test probability of IBD. Performing FC testing in all children was cost-effective when IBD prevalence was below 65%. The turning point, where direct endoscopic evaluation becomes more cost-effective is situated at an IBD prevalence of more than 80%. We did not evaluate the cost-effectiveness of using a test combination of FC, CRP and haemoglobin. Since the publication of Yang et al. the price of a FC test has been reduced from €40 to €25, and the optimal cut-off point has increased from 50 to 250 µg/g. Furthermore, the cost of endoscopic evaluation with biopsies in day care has increased in recent years. These trends likely make the cost-effectiveness of our triage strategy, including FC analysis, even more favorable. Applicability in the primary care setting Our test-strategy was evaluated in second- and third-line care settings, but not in primary care. In primary care, where IBD prevalence is low, an isolated positive FC result is rarely indicative of IBD, but an FC result below 50 µg/g on the other hand, does rule out IBD.(13) The decision to refer children for endoscopy should therefore not be made at the general practitioner’s level, but at the level of the paediatrician. General discussion 119