Kidney microRNA-21 Expression and Kidney Function in IgA NephropathyPlain-Language Summary

Rationale & Objective: Previous studies have suggested that microRNA-21 (miR-21) plays an important role in kidney fibrosis. We examined the relationship between intrarenal miR-21 level and rate of kidney function loss in immunoglobulin A nephropathy (IgAN). Study Design: Prospective cohort study. Setting & Participants: 40 patients with IgAN and 10 with hypertensive nephrosclerosis as controls. Predictors: miR-21 levels in kidney biopsy specimen and urinary sediment, quantified as ratio to the housekeeping gene. Outcomes: Kidney event–free survival and rate of kidney function decline. Analytic Approach: Time-to-event and correlation analysis. Results: The IgAN group had significantly higher intrarenal miR-21 expression compared with the hypertensive nephrosclerosis group (1.71 [IQR, 0.99-2.77] vs 0.31 [IQR, 0.25-1.32]; P