Examining eGFR Slopes and Changes in Proteinuria in IgA Nephropathy, with Jonathan Barratt, MD

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Joanthan Barratt, MD, discusses the results of a RaDaR analysis aimed at examining trends in time-averaged proteinuria and eGFR slope in patients with IgA nephropathy.

New data presented at the American Society of Nephrology Kidney Week 2023 is providing an updated overview of disease progression in patients with IgA nephropathy who progress to end-stage kidney disease.

An analysis of patients enrolled in the UK National Registry of Rare Kidney Diseases (RaDaR), results of the analysis provide insight into the disease course of the most common glomerular disease, with results offering insight into the rate of eGFR loss and time-averaged proteinuria among these patients.

supported and coordinated by the UK Kidney Association, the RaDaR database contains data from more than 100 NHS sites and provided investigators with information from 26,913 UK patients. Investigators designed the current study to include a pair of cohorts.

The first was aimed at assessing the annualized mean slope of eGFR and the second was aimed at assessing change in time-averaged proteinuria, with both assessed before and after progressing through a 45 mL/min/1.73m2. For inclusion in the current analysis, investigators required patients to have a primary kidney diagnosis date or date of biopsy recorded in RaDaR and have at least 3 or more eGFR values before and after progressing through the aforementioned threshold.

Overall, 184 patients were identified for inclusion in the eGFR slope analysis and 195 were identified for inclusion in the time-averaged proteinuria analysis.

Results of the adjusted analysis suggest the rate of eGFR decline was similar before and after progressing through the eGFR threshold. Specifically, the eGFR slope before progressing through the 45 mL/min/1.73m2 threshold at -7.2 (95% confidence interval [CI], -8.4 to 6.0) and -7.0 (95% CI, -8.2 to -5.8) after progressing through the threshold. In contrast, TA-PU was 41.4% greater in patients after progressing through the 45 ml/min/1.73m2 threshold (1.11 [95% CI, 0.64 to 1.89] vs 1.57 [95% CI, 0.95 to 2.67]).

Check out our interview with study investigator Jonathan Barratt, MD, Mayer Professor of Renal Medicine at the University of Leicester, for further insight into the study and how it informs real-world management of IgA nephropathy.

Relevant disclosures for Barratt included Calliditas Therapeutics, Alnylam Pharmaceuticals, Travere Therapeutics, Chinook Therapeutics, Novartis, and others.


  1. Pitcher D, Braddon FE, Hendry BM, et al. Rate of Loss of eGFR and Time-Averaged Proteinuria in IgA Nephropathy (IgAN) Patients Progressing from Early-Stage Disease to Kidney Failure. Paper Presented at: American Society of Nephrology Kidney Week 2023. November 1-5, 2023.
  2. Radar database. RaDaR database | The UK Kidney Association. Accessed November 5, 2023.