The diagnostic accuracy of faecal calprotectin in investigations for suspected inflammatory bowel disease in children

Thank you for providing guidance for adults with suspected inflammatory bowel disease (IBD).¹ Unfortunately paediatric gastroenterologists receive more referrals to endoscope children on the basis of a ‘positive’ faecal calprotectin test based on the false interpretation of a cut-off of 50 µg/g faeces as a surrogate for IBD in children. However, the meta-analysis clearly illustrates an important age-dependent difference of applying the test in children (0–16 years). Although the sensitivity of the test is comparable, the specificity of the test in children is only 76% compared with 96% in adults.² In a retrospective analysis of 190 children, faecal calprotectin was positive (above 50 ng/g faeces) in 91 children of the control group with IBS, non-specific colitis, post-infectious enteropathy, cows’ milk/wheat intolerance, pinworms/enterobius, allergic enteropathy, food allergies, worms, coeliac disease, miscellaneous, or no pathology identified, with a median of 65 µg/g faeces in the non-IBD control group (range 20–235).³ To achieve a comparable specificity of 95% the sensitivity would decrease to 73% with a cut-off for the test as great as 800 µg/g faeces.

We welcome very much all efforts to diagnose IBD much earlier in children. As practical advice, we recommend the referral of children with results >50 mg/g to a paediatrician, and certainly with results of >800 ng/g, or all children with a high clinical suspicion of IBD directly to a paediatric gastroenterologist.

To enable a rapid assessment of children with red-flag signs, the GP’s thoroughness in providing all necessary clinical information (symptoms, growth/height/percentiles and documented changes, stool frequency, consistency, blood in stool), family history, and blood test results (full blood count, C-reactive protein, erythrocyte sedimentation rate, albumin, urea + electrolytes, tissue transglutaminase with immunoglobulin A levels) is essential for prioritisation and eligibility for endoscopy. To avoid unnecessary endoscopies or inadequate prioritisation, these data need to be communicated widely to GP teams.