Kidney outcomes associated with haematuria and proteinuria trajectories among patients with IgA nephropathy in real‐world clinical practice: The Japan Chronic Kidney Disease Database

Abstract

AbstractAimAmong patients with Immunoglobulin A (IgA) nephropathy, we aimed to identify trajectory patterns stratified by the magnitude of haematuria and proteinuria using repeated urine dipstick tests, and assess whether the trajectories were associated with kidney events.MethodsUsing a nationwide multicentre chronic kidney disease (CKD) registry, we analysed data from 889 patients with IgA nephropathy (mean age 49.3 years). The primary outcome was a sustained reduction in eGFR of 50% or more from the index date and thereafter. During follow‐up (median 49.0 months), we identified four trajectories (low‐stable, moderate‐decreasing, moderate‐stable, and high‐stable) in both urine dipstick haematuria and proteinuria measurements, respectively.ResultsIn haematuria trajectory analyses, compared to the low‐stable group, the adjusted hazard ratios (HRs) (95% confidence interval [CI]) for kidney events were 2.59 (95% CI, 1.48–4.51) for the high‐stable, 2.31 (95% CI, 1.19–4.50) for the moderate‐stable, and 1.43 (95% CI, (0.72–2.82) for the moderate‐decreasing groups, respectively. When each proteinuria trajectory group was subcategorized according to haematuria trajectories, the proteinuria group with high‐stable and with modest‐stable haematuria trajectories had approximately 2‐times higher risk for eGFR reduction ≥50% compared to that with low‐stable haematuria trajectory.ConclusionAssessments of both haematuria and proteinuria trajectories using urine dipstick could identify high‐risk IgA nephropathy patients.