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

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.

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.

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/1.73 m2 /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/1.73 m2 /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.

Hematuria remission, defined by the newly proposed stricter criteria, could be a potent prognostic factor in IgAN with straightforward applicability in clinical practice.