Remission of hematuria is associated with a better prognosis in immunoglobulin A nephropathy

Background:The clinical significance of hematuria in immunoglobulin A nephropathy (IgAN) remains unclear.We defined remission of hematuria using stricter yet more intuitive criteria than those in previous studies and evaluated its association with prognosis in IgAN.Methods: This retrospective, multicenter, observational study enrolled 403 patients with IgAN.Hematuria remission was defined as hematuria persisting for at least 3 months before and after diagnostic biopsy, followed by the absence of erythrocytes in four consecutive high-power field microscopic examinations at 3-4-month intervals.Clinical outcomes were compared between the hematuria remission (remission) and persistent hematuria (persistent) groups.Results: The mean annual rate of estimated glomerular filtration rate (eGFR) decline was lower in the remission group than in the persistent group (-1.51 ± 2.86 vs. -2.60 ± 3.18 mL/min/1.73m 2 /yr, p = 0.002).In the remission group, the mean annual rate of eGFR decline decreased after hematuria disappearance (from -1.28 ± 7.06 to 0.09 ± 0.29 mL/min/1.73m 2 /yr, p = 0.02).The proportion of ≥50% decline in eGFR from baseline was also lower in the remission group (p = 0.03).Hematuria remission was an independent prognostic factor of ≥50% decline in eGFR from baseline (hazard ratio, 0.55; 95% confidence interval, 0.33-0.99).However, progression to end-stage kidney disease did not differ significantly between two groups (p = 0.08).Similar results were obtained for propensity score matching.Conclusion: Hematuria remission, defined by the newly proposed stricter criteria, could be a potent prognostic factor in IgAN with straightforward applicability in clinical practice.