Kidney Week

Abstract: TH-PO494

Proteinuria and Its Association With Disease Progression in IgA Nephropathy: Analysis of the UK National RaDaR IgA Nephropathy Cohort

Session Information

• Glomerular Diseases: Clinical, Outcomes, Trials - I
  November 03, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1303 Glomerular Diseases: Clinical‚ Outcomes‚ and Trials

Authors

• Pitcher, David, UK Renal Registry, Bristol, United Kingdom

David Pitcher,

• Braddon, Fiona E. M., UK Renal Registry, Bristol, United Kingdom

Fiona E. M. Braddon,

• Hendry, Bruce M., Travere Therapeutics Inc, San Diego, California, United States

Bruce M. Hendry,

• Mercer, Alex, JAMCO Pharma Consulting, Stockholm, Sweden

Alex Mercer,

• Osmaston, Kate, UK Renal Registry, Bristol, United Kingdom

Kate Osmaston,

• Saleem, Moin, University of Bristol, Bristol, United Kingdom

Moin Saleem,

• Steenkamp, Retha D., UK Renal Registry, Bristol, United Kingdom

Retha D. Steenkamp,

• Turner, A. Neil, University of Edinburgh, Edinburgh, United Kingdom

A. Neil Turner,

• Wang, Kaijun, Travere Therapeutics Inc, San Diego, California, United States

Kaijun Wang,

• Barratt, Jonathan, University of Leicester, Leicester, United Kingdom

Jonathan Barratt,

• Gale, Daniel P., Royal Free Hospital, London, United Kingdom

Daniel P. Gale,

Background

Primary IgA nephropathy (IgAN) is the most common form of glomerulonephritis worldwide and a major cause of renal failure. Here we investigate the relationship between proteinuria (PU) measured over follow-up (FU) and rate of renal function loss and renal survival in patients from the UK National Registry of Rare Kidney Diseases (RaDaR) IgAN Cohort. Since 2013, patients with biopsy-proven IgAN and eGFR <60 ml/min/1.73m² or PU ≥0.5g/24h have been enrolled from 87 kidney units across the UK, with automated collection of retrospective and prospective laboratory data.

Methods

923 patients met the eligibility criteria, including diagnosis date, PU measurements in FU (within 2yr from diagnosis and ≥2 values if FU >3yr), no ESKD (CKD stage 5 or renal replacement therapy) or death within 6mo from diagnosis or prior to first PU value. Longitudinal PU, assessed as time-average protein-to-creatinine ratio (TA-PCR), and eGFR slope were calculated over the full duration of FU or until ESKD or death. For survival analyses, ESKD/death was applied, with survival time calculated from diagnosis to last FU.

Results

Characteristics at diagnosis and clinical outcomes of the study population are summarized in Fig.1a. Increasing grades of TA-PCR were associated with more rapid decline in eGFR (ANOVA p<0.001, Fig.1c) and greater risk of ESKD/death (Log-rank p<0.001, Fig.1b; Cox regression p<0.001, Fig.1c).

Conclusion

Proteinuria exposure over time is significantly associated with disease progression and renal outcomes in IgAN. In particular, TA-PCR below 100 mg/mmol (~1g/24h) is very strongly associated with slower loss of renal function and lower risk of ESKD or death.

Funding

• Commercial Support – Travere Therapeutics, Inc