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* = Presenting author

P058. Beyond the ordinary diagnostic study: The “real life” accuracy of faecal calprotectin for screening children with suspected inflammatory bowel disease

E. Van de Vijver1, A. Schreuder2, W. Cnossen2, A. Muller Kobold2, P.F. van Rheenen2

1University Hospital Antwerp, Antwerp, Belgium; 2University Medical Center Groningen, Groningen, The Netherlands

Objective: In the diagnostic workup of children with suspected inflammatory bowel disease (IBD), endoscopy of the upper and lower gastrointestinal tract is considered indispensable. In a substantial proportion of suspected children no abnormalities are found during endoscopy. A screening test to increase the likelihood of IBD is desirable to justify preferential endoscopy. The aim of this study was to evaluate the usefulness of faecal calprotectin to identify children with a high likelihood for IBD.

Materials and Methods: Design: This prospective diagnostic accuracy study is a delayed-type cross-sectional study. In all patients faecal calprotectin was measured as index test and ileocolonoscopy or clinical follow up as reference standard. The decision to perform diagnostic tests (including endoscopy) was left to the paediatric gastroenterologist's discretion and was independent of the faecal calprotectin result. IBD diagnosis was confirmed by endoscopic and histological evaluation. The diagnosis “non IBD” was confirmed by negative endoscopy, 6 months of clinical follow-up or until other diagnosis was made.

Setting and Patients: A consecutive series of children suspected of IBD in the northern region of the Netherlands was prospectively recruited from secondary and tertiary care out patient clinics.

Main outcome measures: Reduction of unnecessary endoscopies in patients with suspected IBD.

Results: A total of 117 children were included and 42 of them (36%) had IBD. Using the internationally accepted cut-off of faecal calprotectin (50 μg/g stool), we found a sensitivity of 100% for IBD and a specificity of 71%. When faecal calprotectin and stool culturing are combined the sensitivity is 100% (95% confidence interval 97% to 100%) and the specificity is 81% (74% to 88%). When the decision to schedule patients for endoscopic evaluation is left to the paediatric gastroenterologist's discretion, 68 of the children and teenagers will go on to have endoscopy of which 26 (38%) with a negative result. When the calprotectin result and negative stool cultures are combined in the screening, only 56 patients will be subjected to invasive endoscopy, of which 14 (25%) with a negative result (P = 0.037).

Conclusion: Selecting IBD suspected children for endoscopy based on calprotectin only is not better than the paediatrician's “gut feeling”. However, combining increased faecal calprotectin levels and negative stool cultures significantly reduces the number of unnecessary endoscopies. At the same time normal calprotectin levels are unlikely to be associated with intestinal inflammation and further investigations can be tailored appropriately. This is good news for both patients (less invasive tests) and clinicians (less long waiting lists for endoscopy).

Inclusion criteria
Two or more of the following criteria should be present:
Persisting diarrhoea or recurrent abdominal pain and diarrhoea
Rectal bleeding
Unintended weight loss or linear growth retardation
Peri-anal symptoms (skin tag, fistula, fissure or abscess)
Anaemia or other extra-intestinal manifestations
Increased markers of inflammation (ESR > 20 mm/hr; CRP > 5 mg/L)