Cohort profile: The Swedish Inception Cohort in inflammatory bowel disease (SIC-IBD)
Authors: Salomon Benita , Grännö Olle , Bergemalm Daniel , Strid Hans , Carstens Adam , Hjortswang Henrik , Lundström Maria Ling , Hreinsson Jóhann P , Almer Sven , Bresso Francesca , Eriksson Carl , Grip Olof , Blomberg André , Marsal Jan , Nikaein Niloofar , Bakhtyar Shoaib , Lindqvist Carl Mårten , Hörnquist Elisabet Hultgren , Magnusson Maria K , Keita Åsa V , D’Amato Mauro , Repsilber Dirk , Öhman Lena , Söderholm Johan D , Carlson Marie , Hedin Charlotte R H , Kruse Robert , Halfvarson Jonas 
Published: January 2025

Purpose

There is a need for diagnostic and prognostic biosignatures to improve long-term outcomes in inflammatory bowel disease (IBD). Here, we describe the establishment of the Swedish inception cohort in IBD (SIC-IBD) and demonstrate its potential for the identification of such signatures.

Participants

Patients aged ≥18 years with gastrointestinal symptoms who were referred to the gastroenterology unit due to suspected IBD at eight Swedish hospitals between November 2011 and March 2021 were eligible for inclusion.

Findings to date

In total, 368 patients with IBD (Crohn’s disease, n=143; ulcerative colitis, n=201; IBD-unclassified, n=24) and 168 symptomatic controls were included. In addition, 59 healthy controls without gastrointestinal symptoms were recruited as a second control group. Biospecimens and clinical data were collected at inclusion and in patients with IBD also during follow-up to 10 years. Levels of faecal calprotectin and high-sensitivity C-reactive protein were higher in patients with IBD compared to symptomatic controls and healthy controls. Preliminary results highlight the potential of serum protein signatures and autoantibodies, as well as results from faecal markers, to differentiate between IBD and symptomatic controls in the cohort. During the first year of follow-up, 36% (52/143) of the patients with Crohn’s disease, 24% (49/201) with ulcerative colitis and 4% (1/24) with IBD-U experienced an aggressive disease course.

Future plans

We have established an inception cohort enabling ongoing initiatives to collect and generate clinical data and multi-omics datasets. The cohort will allow analyses for translation into candidate biosignatures to support clinical decision-making in IBD. Additionally, the data will provide insights into mechanisms of disease pathogenesis.

Bullet points on strengths and weaknesses

This large, multicentre inception cohort of newly diagnosed adult IBD patients, with integrated biobanking and prospective material collection, enables exploration of IBD pathophysiology and biomarker discovery.

The inclusion of symptomatic controls with gastrointestinal symptoms mimicking IBD but without evidence of the diagnosis provides a realistic diagnostic setting and addresses limitations of many previous cohorts.

The use of healthy controls as a second control group offers opportunities to gain insight into IBD pathogenesis.

The non-population-based study design and the predominance of university hospitals in recruitment may limit the generalisability of findings.

Suboptimal sample processing at some centres, including delays in serum centrifugation and transportation of faecal samples at ambient temperatures, may have affected the quality of some specific analyses, such as microbiota analyses.