Assessing the correlation between fecal calprotectin, blood markers and disease activity in pediatric inflammatory bowel disease.

Background: Crohn's disease (CD) and ulcerative colitis (UC) are the 2 main types of inflammatory bowel disease (IBD), a chronic inflammatory condition of the gastrointestinal tract. Management of IBD necessitates frequent clinical monitoring, including blood tests and occasionally endoscopy. Fecal calprotectin (FC) is a non-invasive measurement of luminal inflammatory activity, and can therefore be used as a useful monitoring tool. This study aimed to assess the relationship between FC, IBD activity indices and the commonly used blood markers in pediatric IBD.

Methods: Electronic patient records were accessed to retrospectively collect patient data from a tertiary pediatric hospital from 2015-2021. CD and UC disease activity was quantified using the Pediatric CD Activity Index (PCDAI) and Pediatric UC Activity Index (PUCAI), respectively. The Paris classification was used for phenotype identification.

Results: A total of 208 patients were included in the study, 115 with CD (18% <10 years and 82% 10-17 years) and 93 with UC (32% <10 years and 68% 10-17 years). There was a positive correlation between FC and PCDAI (r_s=0.546, P<0.001) and between FC and PUCAI (r_s=0.485, P<0.001). FC and activity indices were correlated positively with inflammatory markers/platelets and negatively with albumin and hemoglobin. FC correlated positively with PCDAI in all CD phenotypes, including isolated ileal disease.

Conclusion: In pediatric IBD, FC shows a positive correlation with the clinical picture and blood markers in all disease phenotypes, and can provide an accurate non-invasive measure of disease activity.