Rare kidney diseases and kidney failure: a longitudinal analysis

In high-income countries, the most common causes of mild-to-moderate CKD are diabetes and hypertension. Rare kidney diseases, of which there are over 150, are defined as those affecting fewer than one in 2000 individuals in the population.

Though individually rare, collectively these conditions have a significant impact. Despite representing 5%–10% of those with CKD, people with rare kidney diseases constitute more than 25% of those receiving kidney replacement therapy in the UK. As part of a strategy to understand the reasons for this discrepancy, the UK Kidney Association established the National Registry of Rare Kidney Diseases (RaDaR) in 2010. 

For this study, RaDaR data from 27,285 recruits (aged 0–96 years) was used to describe the clinical demographics, disease characteristics, and kidney and patient outcomes in 28 rare disease groups. The median follow-up from diagnosis was 9.6 years.

Over five years, RaDaR participants were significantly more likely to experience kidney failure compared to the 2.81 million CKD patients in the general population (28% vs 1%; P<0.0001). However, their survival rates were higher (standardised mortality ratio, 0.42 [95% CI, 0.32–0.52]; P<0.0001).

There was substantial variation between rare diseases in the median age at kidney failure, median age at death, time from start of dialysis to death, time from diagnosis to eGFR thresholds and therapeutic trial window (an estimate of the time from diagnosis when renal function would be sufficient to participate in a standard therapeutic trial).

The over-representation of rare kidney diseases in the population with kidney failure suggests that addressing the unmet need for treatments to protect the kidneys in rare diseases could have a disproportionately beneficial effect on kidney replacement therapy demand. _­An opportunity exists, therefore, to reduce the burden of kidney failure on patients and health systems.

The full article can be read here.