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Exploring rare kidney diseases: insights from the world’s largest registry – RaDaR

21 November 2023

In a recent paper, published as a preprint (an academic paper that has been shared publicly but has not yet been published in a journal), a team of researchers led by Professor Danny Gale from University College London, have shown that people from different ethnic and social backgrounds seem to be represented fairly in the National Registry of Rare Kidney Diseases (RaDaR).

RaDar is a big database set up with support from Kidney Research UK that collects long-term data from people in the UK with rare kidney diseases – confirming that this is a powerful source of real-world data that can help us to understand these rare conditions and provide information for research and clinical trials. 

What is a rare disease? 

A ‘rare disease’ refers to a medical condition that affects a relatively small number of individuals within a population. In the UK, a disease is considered rare if it affects fewer than one in 2,000 people. While each disease might be rare on its own, collectively, rare diseases are common. Globally, more than 25% of adults and 50% of children with kidney failure have a rare disease.  

The challenge of studying rare diseases 

Researching rare diseases can be challenging because, by definition, they affect a small number of individuals. This makes it much harder to gather enough information about the diseases, to make sure enough experts have knowledge, and to get funding to research and develop treatments. This is particularly true for many kidney conditions as they are often chronic, meaning patients will be living with them for a long time, so their information may be scattered across different databases, systems and healthcare providers, making it difficult to access all at once. 

What is a registry and what is RaDaR? 

A registry is a collection of information about a specific group of people. Registries are really useful for studying rare diseases because they collect information from people who have these conditions into one place, making it much easier to find patterns, learn more about diseases, identify groups eligible for clinical trials and ultimately develop better treatments.   

RaDaR was set up in 2010 with funding from Kidney Research UK and Kidney Care UK and is supported and coordinated by the UK Kidney Association. It is a system that stores important long-term data and information about people in the UK with rare kidney diseases, including where they live, any treatment they are receiving and how they are responding to that treatment, as well as relevant blood test and imaging results.  

RaDaR is the largest rare kidney disease registry in the world and has recruited over 25,880 patients from 108 UK hospitals and the goals are to: 

  • Learn more about how rare kidney diseases develop and progress over time. 
  • Study the long-term effects of treatments. 
  • Create a system to help with research on specific rare diseases and other smaller registries. 

Confirming RaDaR accurately represents our population 

In their recent paper, Danny and the team presented information about 25,880 adults and children recruited to RaDaR, including ethnicity, socioeconomic status and kidney function and check to see if there is any bias (consistent errors or prejudice in the way the data was collected) in the process of recruiting participants. Biased recruitment would mean that the people who participate may not accurately represent the broader patient population, leading to results that might not apply to everyone. 

The team found that there seemed to be more patients with South Asian ethnicity with some rare diseases, but overall, they didn’t find any biases based on ethnicity or social status that were significant enough to wrongly influence our overall understanding of these rare kidney diseases.  

Insights into rare diseases 

The study also showed that the most common rare kidney diseases in adults were autosomal dominant polycystic kidney disease, vasculitis and IgA nephropathy, and in children, they were idiopathic nephrotic syndrome, vasculitis and Alport syndrome. Children in RaDaR were more likely to be of Asian ethnicity and live in more deprived areas, compared with adults or the general UK population.  

"RaDaR is the result of sustained support and contributions from hundreds of people across the whole UK kidney disease community and it is important to be able to see how fairly it collects information across all groups. We are currently working on a paper that reports what has happened to patients diagnosed with rare kidney diseases that reveals the risk of kidney failure in all age groups in each rare disease. We hope this information will guide improvements in treatments and provision of healthcare resources in this group by making it clear how substantial the unmet needs are among people with these rare diseases. Professor Danny Gale

Professor Daniel Gale
Professor Daniel Gale

Making healthcare equal for all

Elaine Davies, director of research operations at Kidney Research UK said: “RaDaR is a fantastic resource that will help us find answers and make a real difference in the lives of those facing rare diseases and we are proud to continue to support it. Making sure healthcare is equal for all is one of our urgent priority areas in our research strategy and we are thrilled to see these results showing that RaDaR accurately represents the whole kidney community.” 

For links to all publications and posters visit the RaDaR website

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