Kidney Care UK has joined other organisations in calling for further research into dialysis treatments following the results of one of the UK's largest ever dialysis trials.
Around 30,000 people in the UK rely on dialysis to survive, but depending on age and other health problems up to half of that number may die within five years, and survival has not improved in decades. Complications such as heart attacks and strokes are common. People on dialysis also frequently suffer from vitamin D deficiency.
The SIMPLIFIED trial was started in 2017; and led by Cambridge University Hospitals NHS Foundation Trust (CUH) and the University of Cambridge. Funded by the National Institute for Health and Care Research (NIHR), the study investigated the effect of giving high doses of vitamin D to people on dialysis.
The study involved more than 3,800 patients from 55 dialysis centres across England, Scotland and Wales and looked at whether a high dose of vitamin D could improve survival rates for people on dialysis, while avoiding complications.
Half of the patients in the trial received normal care, while half were given an additional high dose of vitamin D every two weeks. Participants were then followed for several years until the trial completed in October 2025 to understand whether the treatment had any benefits.
While the overall results found no benefits, there were possible interesting findings for non-white patients and men, prompting calls for further research from researchers and patient support groups including Kidney Care UK.
Shockingly, treatments for people with kidney failure have barely changed in the last couple of decades, so research into ways life could be improved for people on dialysis is vital. By pointing to where vitamin D supplementation may potentially be effective, for those in under-represented groups, the outcomes of the SIMPLIFIED study are beneficial. We now need more investment to develop these initial research findings further.Fiona Loud, Policy Director at Kidney Care UK
Reasons for hope
31-year old Sameer Solomon took part in the study. Sameer is a member of Kidney Care UK’s Patient Advisory Group (PAG) and was a member of our Young Adult Kidney Group.
Sameer was diagnosed with late-stage kidney disease in early 2020 and has been on dialysis for over three years. He currently spends more than 70 hours a week on dialysis, balancing treatment with work and other demands.
The burden of kidney disease and care is enormous, yet research remains underfunded and treatment options are limited. That’s why this trial, and the wider research it contributes to, is so important. It gives me hope that we can drive progress towards better treatments, improved care, and a brighter future for people living with kidney disease.
One of the reasons I feel it’s important to take part in research is because people of colour are often underrepresented. These results show why this is so important. I’m glad I was able to take part, and I hope this will encourage others to do the same. People of colour in the UK are already more likely to be lacking vitamin D so the need for more focused research is key.
You can more about the SIMPLIFIED trial on the Cambridge University Hospitals website.