Immunoglobulin A nephropathy in association with inflammatory bowel diseases: results from a national study and systematic literature review
Nizar Joher, Clément Gosset, Dominique Guerrot, Évangéline Pillebout, Aurélie Hummel, Jean‐Jacques Boffa, Stanislas Faguer, Marion Rabant, Sarah Higgins, Anissa Moktefi, Yahsou Delmas, Alexandre Karras, Nathanaël Lapidus, Aurélien Amiot, Vincent Audard, Khalil El Karoui
Abstract
BACKGROUND: Little is known about clinical characteristics and kidney outcomes in patients with biopsy-proven immunoglobulin A nephropathy (IgAN) in a context of inflammatory bowel disease (IBD). METHODS: We conducted a retrospective multicentre study with a centralized histological review to analyse the presentation, therapeutic management and outcome of 24 patients suffering from IBD-associated IgAN relative to a cohort of 134 patients with primary IgAN without IBD. RESULTS: Crohn's disease and ulcerative colitis accounted for 75 and 25% of IBD-associated IgAN cases, respectively. IBD was diagnosed before IgAN in 23 cases (a mean of 9 years previously) and was considered active at IgAN onset in 23.6% of patients. Hypertension was present in 41.7% of patients. The urinary protein:creatinine ratio exceeded 100 mg/mmol in 70.8% of patients (mean 254 mg/mmol). Estimated glomerular filtration rate (eGFR) was >60 mL/min/1.73 m2 in 13/24 patients and only 1 patient required dialysis. In the Oxford mesangial hypercellularity, endocapillary cellularity, segmental sclerosis and interstitial fibrosis/tubular atrophy with crescents classification of renal biopsies, 57% were M1, 48% E1, 76% S1, 57% T1-2 and 38% C1-2. Steroids were administered in 50% of cases. After a mean follow-up of 7.2 years, 4 patients (16.7%) had a poor kidney outcome: end-stage renal disease (n = 3) or a >50% decrease in eGFR from initial values (n = 1). A similar evolution was observed in patients with primitive IgAN. CONCLUSIONS: This first case series suggests that IBD-associated IgAN has frequent inflammatory lesions at onset and variable long-term outcomes.