Best epidemiological abstracts at ECCO’26

Zhuang H, et al. (OP14, Risk of Inflammatory Bowel Disease Following Hospital-Treated Infections and Modulatory Role of Host Genetics to support a multi-hit pathogenesis model): This study, which received the Y-ECCO Best Abstract Award at ECCO'26, investigated whether infections contribute to IBD pathogenesis and how host genetics modulates this relationship. In a prospective cohort of 359,636 UK Biobank participants, hospital-treated infections were associated with a markedly increased risk of subsequent IBD (aHR 3.44; 95% CI 3.14–3.77), with elevated risks observed across all major pathogen types (bacterial, viral, fungal and parasitic) and seven anatomical sites. Among 51 immune-related genes examined, 44 showed significant modifying effects on the infection–IBD association. Pathway analyses revealed shared yet distinct immune mechanisms, with Crohn's Disease (CD) enriched in innate immune and autophagy pathways and Ulcerative Colitis (UC) in JAK-STAT signalling and T-cell differentiation. An Infection IBD Score constructed from these 44 variants stratified post-infection susceptibility, with aHRs of 3.15 (95% CI 2.86–3.48) and 6.35 (95% CI 4.83–8.35) in the low- and high-score groups, respectively, and was further validated by proteomic analyses. These findings support a multi-hit model of IBD pathogenesis, in which infections act as triggers in genetically susceptible individuals, and suggest a potential tool for infection-based risk stratification [1].

Sun J. Risk of cardiovascular disease in patients with inflammatory bowel disease (ECCO Research Grant, Epidemiology project): We are also pleased to report the successful completion of the epidemiology project led by Jiangwei Sun (Karolinska Institutet, Sweden), supported by an ECCO Research Grant awarded in 2024, whose final report was received in April 2026. The project aimed to investigate the long-term absolute and relative risk of cardiovascular disease (CVD) in patients with IBD and to assess how CVD risk varies according to histological and clinical disease activity, using a comprehensive linkage of a nationwide histopathology cohort, a quality register for IBD and several nationwide registers in Sweden. A series of nationwide cohort studies, comparing patients with IBD with the general population and with their IBD-free full siblings, demonstrated an increased risk of heart failure, myocarditis, arrhythmias, stroke, acute coronary syndrome and venous thromboembolism, whereas no excess CVD risk was observed among family members of patients with IBD [2, 3]. With regard to disease activity, histological inflammation was associated with an increased risk of major adverse cardiovascular events compared with histological remission (aHR 1.16; 95% CI 1.04–1.30), an association evident in both CD and UC, and clinically active disease was associated with an even greater excess risk (aHR 1.54; 95% CI 1.46–1.63) [4]. Notably, in patients with clinically quiescent IBD, histological inflammation remained associated with myocardial infarction and heart failure. A companion study reported analogous findings for arrhythmias (aHR 1.35; 95% CI 1.18–1.54). Overall, this project, which has already generated several publications in leading journals, indicates that awareness of the excess cardiovascular risk in patients with IBD is warranted and suggests that improved disease control may help mitigate this risk, providing valuable evidence for the future development of clinical guidelines on CVD management in IBD.

With epidemiological research continuing to broaden its scope, from aetiological hypotheses and gene–environment interactions to long-term comorbidity risk, we encourage researchers to start shaping their own epidemiological studies for submission to ECCO'27 in Copenhagen. This is an opportunity to contribute valuable insights into this rapidly evolving field!