IgAN, Kidney Disease Common Among Patients with Inflammatory Bowel Disease

Prasanth Ravipati, MD

Credit: University of Nebraska Medical Center

Immunoglobulin A nephropathy (IgAN), interstitial nephritis, and diabetic nephropathy were the most frequent findings among a cohort of individuals with inflammatory bowel disease (IBD) who underwent kidney biopsy, highlighting the prevalence of advanced kidney disease in this patient population.

Results from the retrospective cohort study of veteran patients from the VA Corporate Data Warehouse called attention to a short latency between kidney biopsy, the development of end-stage kidney disease (ESKD), and eventual death, alluding to potential delays and shortcomings in renal disease diagnosis that may benefit from additional screening parameters.¹

According to the Crohn’s and Colitis Foundation, between 25-40% of patients with IBD experience extraintestinal manifestations outside of the gut, commonly in the joints, skin, bones, eyes, kidneys, and liver. Although the general understanding of the pathogenesis of Crohn disease (CD) and ulcerative colitis (UC) has improved, the etiology of many extraintestinal manifestations, including renal involvement, remains unclear and requires further research in order to establish appropriate kidney functionality monitoring in this patient population.^2,3

“The most common kidney pathology associated with IBD is that of immunoglobin A nephropathy (IgAN), but other glomerular and tubulointerstitial diseases have been described. Many reports are limited to single centers, with short follow-up,” wrote investigators.¹

To address these limitations and fill potential gaps in existing research, Prasanth Ravipati, MD, assistant professor in the department of internal medicine and division of nephrology at the University of Nebraska Medical Center, and a team of investigators compared baseline clinical characteristics and indications for kidney biopsy as well as histopathologic findings among individuals with IBD. Using patient data from the VA Corporate Data Warehouse, investigators identified a cohort of 140 US veterans diagnosed with UC or CD who received a kidney biopsy to evaluate for intrinsic kidney disease between January 1, 2000, and June 30, 2018. The primary outcomes of interest were GFR loss, initiation of kidney replacement therapy, and all-cause mortality.¹

The majority of study participants were White (80%), male (92.9%), and had UC (65%). The mean age at IBD diagnosis was 45.2 (Standard deviation [SD], 16.4) years for UC and 37.9 (SD, 15.5) years for CD. The mean age at kidney biopsy was 62 (SD, 14.1) years for UC and 60.5 (SD, 12.6) years for CD. Among the cohort, the indications for kidney biopsy included acute kidney injury or CKD (76.5%), proteinuria (20%), and hematuria (3.5%).¹

Investigators also called attention to significant differences in overall prescribing patterns based on disease type. Compared to patients with CD, those with UC were more likely to be prescribed mesalamine/balsalazide (47.3% vs 32.6%) and tumor necrosis factor inhibition (13.2% vs 2%), but they were less likely to be prescribed prednisone (31.9% vs 36.7%) and rectal hydrocortisone (2.2% vs 22.4%).¹

The 5 most common primary diagnoses on kidney biopsy were IgA nephropathy (17.1%), diabetic nephropathy (14.3%), interstitial nephritis (9.3%), focal segmental glomerulosclerosis (8.6%), and membranous nephropathy (5.7%). Compared to patients with CD, those with UC were more likely to have biopsy findings consistent with IgA nephropathy (17.6% vs 16.3%) or diabetic nephropathy (18.7% vs 6.1%), and less likely to have findings consistent with interstitial nephritis (8.8% vs 10.2%), focal segmental glomerulosclerosis (5.5% vs 14.3%), or membranous nephropathy (4.4% vs 8.2%).¹

A total of 24 (26%) patients with UC and 10 (20%) with CD progressed to ESKD, with a mean time from kidney biopsy of 3.1 (SD, 4.2) years and 1.9 (SD, 1.8) years, respectively. Among patients with UC, 41 (45%) died within a mean time from kidney biopsy of 4.3 years. Additionally, 17 (34%) patients with CD died within a mean time from kidney biopsy of 4.6 years.¹

Among the 3 most common diagnoses, progression to ESKD occurred in 38% of patients with IgAN, 29% of patients with diabetic nephropathy, and 33% of patients with interstitial nephritis.¹

Although investigators expressed confidence in the size of the study’s cohort and the specificity of identifying participants’ IBD diagnosis as CD or UC, they also highlighted several potential limitations. These included but were not limited to the male predominance of US veterans, retrospective study design, and older patient population with a severe multimorbidity burden.¹

“The findings of advanced kidney disease at the time of biopsy and short time to ESKD suggest a delay in diagnosis and possibly a low rate of diagnosis. Additional research evaluating the potential benefit of screening for renal disease should be considered,” investigators concluded.¹

References:

1. Ravipati P, Reule S, Bren A, et al. Kidney Biopsy Findings and Clinical Outcomes of US Veterans with Inflammatory Bowel Disease. Glomerular Dis 20 December 2023; 3 (1): 233–240. https://doi.org/10.1159/000534062
2. Crohn’s and Colitis Foundation. Extraintestinal Complications of IBD. Patients & Caregivers. Accessed January 22, 2024. https://www.crohnscolitisfoundation.org/what-is-ibd/extraintestinal-complications-ibd
3. Corica D, Romano C. Renal Involvement in Inflammatory Bowel Diseases. Journal of Crohn's and Colitis. https://doi.org/10.1093/ecco-jcc/jjv138