A distinct serum metabolic signature outperforms C-reactive protein as a non-invasive marker for monitoring disease activity in Inflammatory Bowel Disease

Serum was sampled from HC (n=195; Deutsche Zentrum für Herz-Kreislauf-Forschung cohort [DZHK]) and IBD patients. For UC, serum samples were collected within longitudinal (n=92) and cross-sectional cohorts (n=91) from the University Hospital Schleswig-Holstein, Campus Kiel (UKSH), Germany. For CD, longitudinal cohorts were used (n=98, UKSH). In longitudinal studies, sampling was performed at w0, 2, 14, 24 and 26, with the majority of samples collected in w0 (prior to) and w14 (after initiation of advanced therapy). Disease activity was monitored at each timepoint and based on the endoscopic Mayo score (eMayo), the histopathological Nancy score (only available for Kiel cohorts), clinical disease activity (PRO2), and serum CRP. For CD, measures included the Crohn’s Disease Activity Index (CDAI), the Simple Endoscopic Score for Crohn’s Disease (SES-CD), and CRP. Inactive UC was defined as eMayo≤1, PRO2≤1, Nancy≤1, or CRP≤5mg/l. Inactive CD was defined as CDAI≤220, SES-CD≤6 or CRP≤5mg/l. Endoscopic (eMayo≤1/SES-CD≤6) and clinical remission (PRO2≤1/CDAI≤220) were assessed in w14.