| Description: |
Background: The UK Registry of Rare Kidney Diseases (RaDaR) Idiopathic Nephrotic Syndrome cohort includes adults and children with genetic nephrotic syndrome, Focal Segmental Glomerulosclerosis (FSGS) and minimal change disease. This study examines long-term patient outcomes as a function of kidney biopsy diagnosis and proteinuria control. Methods: 2467 adults and 1599 children were followed to establish outcomes including eGFR slope and kidney survival by diagnosis, analysed as a function of proteinuria from disease onset for FSGS and minimal change disease. Enrollment began in 2010, with follow-up to September 2023. Index date for the survival analyses was date of disease onset. Results: The cohort had median [IQR] follow up of 8.2 [4.3-13.1] years; 30% of patients reached kidney failure or died. 1303 patients had FSGS, 1153 minimal change disease, 105 monogenic nephrotic syndrome. Children showed relatively preserved mean kidney function at disease onset (eGFR>100 ml/min/1.73m2), compared to adults (FSGS 61ml/min/1.73m2; minimal change disease 76ml/min/1.73m2). Kidney survival probability (95% CI) at 10 years varied with diagnosis: Genetic 29% (20-38), FSGS 58% (55-61), minimal change disease 87% (85-89) with mean (SD) rates of eGFR loss -26.5 (34.7), -6.2 (14.3), and -1.9 (10.2) ml/min/1.73m2 per year respectively. FSGS 10-year kidney survival (95% CI) for 6-12 months lowest proteinuria value in complete remission (3.5g/g) was 88% (70-96). 65% (50-76) and 37% (26-48), respectively. Time-averaged proteinuria of |