Role of faecal calprotectin as a predictor of endoscopic activity in paediatric patients with ulcerative colitis.

Background: Colonoscopy is currently considered to be the gold standard for evaluation of colonic mucosa inflammation in patients with ulcerative colitis (UC), but the procedure is invasive and cannot be repeated frequently, especially in the paediatric population. The aim of this study was to assess the role of faecal calprotectin (FC) as a predictor of endoscopic disease activity in paediatric patients with UC in clinical remission.

Methods: Single-centre prospective study. Clinical remission was defined as Paediatric Ulcerative Colitis Activity Index <10. Endoscopic findings were assessed according to the Mayo Endoscopic Subscore (MES). MES≤1 was defined as endoscopic remission. All participants provided fresh faecal samples for measurement of FC.

Results: A total of 34 visits of 24 children with UC were included in the study. There was a strong positive correlation between FC levels and endoscopic disease activity (n=34, r=0.83, p<0.001). The median FC levels in the subgroup with endoscopic activity (MES 2-3) were significantly higher than the median FC levels in the subgroup without endoscopic activity (MES≤1) (1000μg/g, IQR 575-1800μg/g vs. 100μg/g, IQR 80-223μg/g, p<0.001). At a cut-off of 298.5μg/g, FC had 92.3% sensitivity, 95.2% specificity and an AUROC 0.974 (SE 0.023, 95% CI 0.93-1, p<0.001) to predict endoscopic activity.

Conclusions: FC is an accurate surrogate marker of endoscopic activity in children with clinically quiescent UC.