IgA Nephropathy Prognosis Worse With Microangiopathy – Renal and Urology News

The presence of microangiopathy is associated with worse prognosis in patients with immunoglobulin A nephropathy (IgAN), investigators report.

In a study of 450 patients with biopsy-proven IgAN, microangiopathy lesions were present in 16.2% and were significantly associated with a 2.1-fold increased risk for the composite kidney outcome, Ying Yao, MD, of Tongji Hospital at Huazhong University of Science and Technology in Wuhan, China, and colleagues reported in Clinical Kidney Journal. The composite outcome included a 50% or greater decrease in estimated glomerular filtration rate, end-stage kidney disease, kidney transplantation, or death. Further, their meta-analysis of 5 cohorts involving 2098 individuals showed a 2.9-fold increased risk of poor renal outcome in patients with vs without microangiopathy after adjustment for confounding variables.

The microangiopathy group had more global glomerulosclerosis and interstitial fibrosis/tubular atrophy on biopsy than other patients with IgAN, according to the investigators. Active lesions exhibited thrombi, endothelial swelling or denudation, mesangiolysis, and fragmented red blood cells in glomeruli, arteries or arterioles. Chronic lesions included double contours of peripheral capillary walls in glomeruli, hyaline deposits in arterioles, and fibrous intimal thickening with concentric lamination (onion skin) in arteries.

To determine IgAN prognosis, pathologists typically calculate the Oxford classification MEST-C score for each patient, reflecting the degree of mesangial hypercellularity (M), endocapillary cellularity (E), segmental sclerosis (S), interstitial fibrosis/tubular atrophy (T) and crescents (C). Dr Yao’s team found that the group with vs without microangiopathy also had certain clinical characteristics, including significantly older age, higher blood pressure, more proteinuria, worse kidney function, and increased uric acid levels. IgA vasculitis did not differ significantly between groups.

In Cox proportional hazards models adjusted for the above confounders as well as MEST-C score and use of steroids and other immunosuppressants, microangiopathy independently correlated with poor outcome.

Microangiopathy is “not rare” among patients with IgAN, Dr Yao’s team pointed out. “Based on these compelling findings, we propose the inclusion of [microangiopathy] lesions in the Oxford classification to enhance the prognostic value for IgAN.” New treatments for IgAN have been approved and explored.