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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.