Patient characteristics, treatment patterns and clinical outcomes of immunoglobulin a nephropathy (IgAN) in China: a retrospective cohort study.

OBJECTIVES: To assess patient characteristics, treatment patterns and clinical outcomes of immunoglobulin A nephropathy (IgAN) in China. DESIGN: Retrospective cohort study. SETTING: Regional electronic health records database from Yinzhou District of Ningbo City, China. PARTICIPANTS: A total of 978 adult patients with biopsy-proven primary IgAN diagnosed between 2015 and 2023. PRIMARY AND SECONDARY OUTCOME MEASURES: Baseline characteristics, treatment patterns before and after renal biopsy, and temporal treatment trends were assessed. Clinical outcomes included composite renal events and estimated glomerular filtration rate (eGFR) decline trajectories according to proteinuria levels at biopsy and during follow-up. RESULTS: Most patients were diagnosed at early chronic kidney disease stages (70.1% stage I-II) but frequently exhibited hypertension (55.0%) and advanced pathological features, with 85.9% classified as Lee grade III-V and 77.8%-98.9% showing M1, E1 or S1 lesions. At biopsy, 65.6% had proteinuria >0.5 g/day. Over a median follow-up of 3 years, 6.7% experienced composite renal events, while 58.2% maintained proteinuria >0.5 g/day. Renin-angiotensin-aldosterone system inhibitors were widely prescribed (91.5%), with increasing use of sodium-glucose cotransporter-2 inhibitors and non-steroidal immunosuppressants and declining corticosteroid use over time. After adjustment for key demographic and clinical factors, persistent proteinuria was associated with higher renal risk and faster eGFR decline. CONCLUSIONS: Despite early diagnosis and strong guideline adherence, persistent proteinuria and adverse outcomes remain common, underscoring the need for more effective therapies in IgAN.