Abstract: FR-PO858
Concordance of Proteinuria Thresholds between Chinese and UK Cohorts with IgA Nephropathy
Session Information
- IgA Nephropathy: Clinical, Outcomes, and Therapeutics
October 25, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Barratt, Jonathan, University of Leicester, Leicester, United Kingdom
- Pitcher, David, UK Kidney Association, Bristol, United Kingdom
- Hirst, Ceri, Novartis Pharmaceuticals UK Ltd, London, United Kingdom
- Gale, Daniel P., Royal Free Hospital, London, United Kingdom
Background
IgA nephropathy (IgAN) is a heterogenous disease with various clinical manifestations, including proteinuria. Proteinuria is a surrogate endpoint for predicting long-term outcomes in IgAN, with KDIGO guidelines identifying proteinuria <1 g/day as a therapeutic target. However, a recent study in China suggests a lower threshold of <0.3 g/day (approximately 26 mg/mmol), with patients below this level having a reduced risk of reaching 50% estimated glomerular filtration rate (eGFR) reduction or end-stage kidney disease (Tang et al. 2024; https://doi.org/10.1053/j.ajkd.2023.12.016). Here, we used the UK RaDaR registry, one of the largest and most comprehensive population-based datasets for patients with IgAN, to evaluate and compare the population differences of IgAN patients in the RaDaR UK and Chinese cohorts. Additionally, we evaluated the concordance of proteinuria findings between these two populations.
Methods
We analyzed a population of 3493 adults with biopsy proven IgAN enrolled on the RaDaR registry up to September 2022 and compared population characteristics and proteinuria findings to the Chinese cohort.
Results
Compared to the Chinese cohort, patients on the UK registry were more likely to be male (70.5% vs 51.4%) and were on average older (42.8 ± 14.4 years vs 36.5 ± 12.0 years). RaDaR patients had a higher stage of chronic kidney disease (69.2% Stage 3+ vs 30.8%), and eGFR was lower (47.8 ± 31.0 vs 78.43 ± 30.45 mL/min/1.73 m2). During follow-up, 2040 (58%) of UK registry patients progressed to kidney failure with a median survival time of 8 (7.5-8.7) years. Survival time was directly correlated with proteinuria, with a notably lower median survival time in patients with proteinuria ≥100 mg/mmol (HR 3.072 (95% CI 2.32-4.06). The median survival for patients with proteinuria <50, 50-99, 100-199, 200-299 and >300 mg/mmol was 10.4 (7.3-NE), 9.7 (7.6-NE), 5.8 (4.3-7.7), 3.3 (2.1-4.8) and 1.4 (0.9-1.9) years, respectively.
Conclusion
While there are population differences between patients with IgAN across cohorts, patients with specific characteristics have a consistently poorer prognosis. Proteinuria levels indicate that risk of kidney failure persists even in patients below the recommended threshold. Therefore, a lower threshold for treatment goals warrants consideration.
Funding
- Commercial Support – Novartis Pharma AG, Basel, Switzerland