Description and Cross-Sectional Analyses of 25,880 Adults and Children in the UK National Registry of Rare Kidney Diseases Cohort

Abstract

Introduction: The National Registry of Rare Kidney Diseases (RaDaR) collects data from people living with rare kidney diseases across the UK, and is the world's largest, rare kidney disease registry. We present the clinical demographics and renal function of 25,880 prevalent patients and sought evidence of bias in recruitment to RaDaR.

Methods: RaDaR is linked with the UK Renal Registry (UKRR, with which all UK patients receiving kidney replacement therapy [KRT] are registered). We assessed ethnicity and socioeconomic status in the following: (i) prevalent RaDaR patients receiving KRT compared with patients with eligible rare disease diagnoses receiving KRT in the UKRR, (ii) patients recruited to RaDaR compared with all eligible unrecruited patients at 2 renal centers, and (iii) the age-stratified ethnicity distribution of RaDaR patients with autosomal dominant polycystic kidney disease (ADPKD) was compared to that of the English census.

Results: We found evidence of disparities in ethnicity and social deprivation in recruitment to RaDaR; however, these were not consistent across comparisons. Compared with either adults recruited to RaDaR or the English population, children recruited to RaDaR were more likely to be of Asian ethnicity (17.3% vs. 7.5%, P-value < 0.0001) and live in more socially deprived areas (30.3% vs. 17.3% in the most deprived Index of Multiple Deprivation (IMD) quintile, P-value < 0.0001).

Conclusion: We observed no evidence of systematic biases in recruitment of patients into RaDaR; however, the data provide empirical evidence of negative economic and social consequences (across all ethnicities) experienced by families with children affected by rare kidney diseases.

Keywords: RaDaR; ethnicity; rare kidney disease registry; rare kidney diseases; social deprivation.

Graphical abstract

Figure 1

Recruitment and data flow to RaDaR. RaDaR, National Registry of Rare Kidney Diseases; UKRDC, UK Renal Data Collaboration; UKRR, UK Renal Registry.

Figure 2

RaDaR patient (a) ethnicity and (b) socioeconomic status, stratified by rare disease group. ADPKD, autosomal dominant polycystic kidney disease; ADTKD, autosomal dominant tubulointerstitial kidney disease; aHUS, atypical hemolytic uremic syndrome; ANCA, antineutrophil cytoplasmic antibody; ARPKD/NPHP, autosomal recessive polycystic kidney disease and nephronophthisis; C3GN, C3 glomerulopathy; FSGS, focal segmental glomerulosclerosis; GBM, glomerular basement membrane; INS, idiopathic nephrotic syndrome; IQR, interquartile range; MCD, minimal change disease; MGRS, monoclonal gammopathy of renal significance; MPGN, membranoproliferative glomerulonephritis; NR, not reported; RaDaR, National Registry of Rare Kidney Diseases; SRNS, steroid resistant nephrotic syndrome; SSNS, steroid sensitive nephrotic syndrome; STEC HUS, Shiga toxin/verotoxin-producing Escherichia coli-associated hemolytic uremic syndrome; TBMN, thin basement membrane nephropathy.

Figure 3

Distribution of recruitment to RaDaR across the United Kingdom. RaDaR, National Registry of Rare Kidney Diseases.

Figure 4

Proportion of rare disease diagnoses for each disorder within UKRR and RaDaR KRT recipients. ADPKD, autosomal dominant polycystic kidney disease; ADTKD, autosomal dominant tubulointerstitial kidney disease; aHUS, atypical hemolytic uremic syndrome; ANCA, antineutrophil cytoplasmic antibody; ARPKD/NPHP, autosomal recessive polycystic kidney disease and nephronophthisis; C3GN, C3 glomerulopathy; FSGS, focal segmental glomerulosclerosis; GBM, glomerular basement membrane; INS, idiopathic nephrotic syndrome; IQR, interquartile range; KRT, kidney replacement therapy; MCD, minimal change disease; MGRS, monoclonal gammopathy of renal significance; MPGN, membranoproliferative glomerulonephritis; NR, not reported; RaDaR, National Registry of Rare Kidney Diseases; SRNS, steroid resistant nephrotic syndrome; SSNS, steroid sensitive nephrotic syndrome; STEC HUS, Shiga toxin/verotoxin-producing Escherichia coli-associated hemolytic uremic syndrome; TBMN, thin basement membrane nephropathy; UKRR, UK Renal Registry.