Treatment patterns, clinical outcomes, and economic burden among patients with immunoglobulin A nephropathy (IgAN) in China

Immunoglobulin A nephropathy (IgAN) is a major cause of kidney failure. This study aimed to investigate the treatment patterns, clinical outcomes, and economic burden of IgAN in China. This was a retrospective multicenter cohort study. Adult patients had biopsy-proven primary IgAN diagnosed between 01/01/2015, and 06/30/2023 in China. The index date was the date of the renal biopsy. Time-to-event analysis was performed for event-free from composite renal events (occurrence of end-stage kidney disease, a 40% decline in eGFR, doubling of serum creatinine, or a mortality event). Associations between proteinuria at renal biopsy and time-averaged proteinuria (TA-P) with composite renal events were estimated using Cox regression. Healthcare visit frequency per follow-up patient-year and costs per capita were calculated. This study included 1,674 patients (median age: 37 years) with 60.27% hypertension. At renal biopsy, the median proteinuria of 1,211 patients was 1.42 g/day and two-thirds of them exhibited proteinuria ≥ 1 g/day. During follow-up (median: two years), renin-angiotensin-aldosterone system inhibitors (69.77%) and corticosteroids (66.98%) were the most prescribed medications for IgAN; and 9.20% of patients experienced composite renal events. The probability of remaining composite renal event-free was 65.1% in the 8th year. Higher proteinuria levels were associated with an increased risk of composite renal events (hazard ratios with 95% confidence intervals: 1.18 [0.49, 2.80] for 0.5–<1 g/day, 1.77 [0.80, 3.94] for 1–<2 g/day, 2.98 [1.25, 7.07] for 2–<3 g/day and 7.73 [3.67, 16.26] for ≥ 3 g/day vs. < 0.5 g/day TA-P). On average, per follow-up year, each patient had seven outpatient nephrology visits, one hospitalization, and 14 days of hospital stay. In 2015–2023, the per capita hospital care cost was 1,847 USD; and costs increased with higher proteinuria levels or advancing chronic kidney disease stages. Results showed that despite of available therapies, patient outcomes remained poor, emphasizing the need for better therapeutic strategies to address the clinical and economic challenges posed by IgAN in China.