Inflammatory bowel disease (IBD) is a common comorbidity among patients with IgA nephropathy (IgAN), and its presence is associated with an increased risk for progression to end-stage kidney disease (ESKD), according to new study findings.

Patients with IgAN have a 3.3-fold higher risk of IBD, including a 2.6-fold higher risk of ulcerative colitis and a 1.6-fold higher risk of Crohn disease (regional enteritis), Louise Emilsson, MD, PhD, of the University of Oslo in Oslo, Norway, and colleagues reported in the Journal of the American Society of Nephrology.

In their Swedish population-based cohort study, IBD developed in 196 of 3963 (4.95%) patients with biopsy-verified IgAN compared with 330 of 19,978 (1.65%) age- and sex-matched controls over a median 12.6 years. Increased risks for IBD were found among both men and women with IgAN and across age-groups.

IBD also commonly developed in patients before an IgAN diagnosis, the investigators reported. In the cohort, 103 (2.53%) of IgAN cases versus 220 (1.09%) of controls had pre-existing IBD. Among patients with IgAN, the investigators found 2.4-fold increased odds for pre-existing IBD, including 2.4-, 2.2-, and 2.4-fold increased odds of pre-existing Crohn disease, ulcerative colitis, and unclassified IBD, respectively.


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The presence of any IBD among patients with IgAN was associated with 2.6-fold increased odds of ESKD in logistic regression analyses and 1.8-fold increased risk of ESKD in time-varying Cox regression analyses. In addition, 50% of patients with both IgAN and IBD progressed to kidney failure compared with 25% of patients with IgAN only and 1.3% of patients with IBD without IgAN.

With respect to potential mechanisms, chronic inflammation in the gastrointestinal mucosa may drive antibody production, including the aberrantly glycosylated antibodies seen in IgAN tissue samples, the study authors noted. Other potential mechanisms for the increased risk for ESKD include different nutritional states and potentially nephrotoxic medications used in patients with IBD, they stated.

“Our findings suggest an association between IBD and IgAN,” Dr Emilsson’s team concluded. “Identification of IBD in patients with IgAN may be useful for the risk prediction of ESKD.” They suggested future studies investigate whether screening and optimized treatment for IBD improve prognosis in patients with IgAN.

Reference

Rehnberg J, Symreng A, Ludvigsson JF, Emilsson L. Inflammatory bowel disease is more common in patients with IgA nephropathy and predicts progression of ESKD: A Swedish population-based cohort study. J Am Soc Nephrol. 2021;32:411-423. doi:10.1681/ASN.2020060848