Abstract: FR-PO0826
Kidney Involvement as an Extraintestinal Manifestation in Inflammatory Bowel Disease: A Population-Based Multicentre Retrospective Study
Session Information
- Glomerular Diseases: Practice and New Concepts Shaping Modern Care
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Author
- Ville, Simon, Centre Hospitalier Universitaire de Nantes, Nantes, Pays de la Loire, France
Background
Renal involvement in inflammatory bowel disease (IBD) is poorly characterized and systematically attributed to drug toxicity (5-ASA, anti-TNF) rather than recognized as a genuine extraintestinal manifestation (EIM). Population-level incidence data and large biopsy cohorts are lacking.
Methods
We conducted (1) a population-based study using the French national health database and (2) a retrospective multicenter cohort study across 11 nephrology centers in Western France (~10 million inhabitants, 2010–2025), systematically identifying IBD patients with native kidney biopsy.
Results
Incidence of biopsy-proven renal involvement was 44.9/100,000 patient-years in IBD vs. 11.2/100,000 in the general population (RR 4.1, 95%CI 3.4–4.9, p<0.001). Among 114 IBD patients with kidney biopsy (median age 42.5y, 30% female), dominant diagnoses were IgA nephropathy/vasculitis (IgAN/IgAV, 32%), chronic interstitial nephritis (CIN, 27%), and acute interstitial nephritis (AIN, 15%). AIN was significantly associated with active IBD at biopsy (56% vs. 11–20% in other groups, p=0.008). Neither prior nor current 5-ASA exposure was associated with interstitial nephritis diagnosis or fibrosis severity (all p>0.05). Granulomatous nephritis occurred in 29% of AIN and 23% of CIN, predominantly in 5-ASA-naive Crohn's disease patients. ESRD-free survival was 92.3% at 5 years. In multivariable Cox analysis, serum creatinine at biopsy (HR 1.02/10µmol/L, p<0.001) and high histological chronicity score (HR 4.6, p=0.041) were independent predictors of kidney failure.
Conclusion
Our results supports renal interstitial nephritis and IgA nephropathy as genuine EIMs driven by gut-kidney inflammatory mechanisms. Renal surveillance should extend beyond nephrotoxic drug monitoring to all IBD patients, and kidney involvement warrants inclusion in EIM registries and treatment guidelines
Distribution of renal biopsy diagnoses in IBD patients.