What is already known about this topic and why is it important?

Hyperphosphataemia is highly prevalent in patients with End Stage Kidney Disease (ESKD) and associated with increased mortality risk. Clinical Practice Guidelines suggest lowering elevated phosphate levels towards the normal range (level 2C suggestion). However, trial data demonstrating that treatments that lower serum phosphate will improve patient-centred outcomes are lacking. Treatment with phosphate-lowering medications is associated with significantly increased pill burden and non-adherence, poor quality of life and substantial adverse effects. Serum phosphate is a biomarker with little or no relevance to patients and Phosphate-lowering medications are a significant financial burden to patients and governments.

How will you carry out your study?

PHOSPHATE is an Investigator-initiated, international, multi-centre, prospective, randomised, open-label, parallel-group, superiority, and pragmatic large simple trial (LST).

How will you decide which patients are included in your study?

Inclusion criteria:

• Age ≥45 years, or Age ≥18 years with diabetes,
• ESKD treated with haemodialysis, or peritoneal dialysis, for at least 3 months,
• Prescribed at least one phosphate-lowering medication at any dose.
• Able to provide informed consent

Exclusion criteria:

• Elective kidney transplantation scheduled,
• Concomitant major illness / comorbidity that may result in death in the next 6 months in the view of the treating physician,
• Participation in an interventional study that is likely to affect serum phosphate concentration.

How many patients do you anticipate including?

2000 UK participants

For how long will you follow up these patients?

Until 1,190 study endpoints have been achieved (estimated 5 years)

What value will UKRR data add to the project?

UKRR phosphate level data is critical to the design of the PHOSPHATE study. Access to routinely collected healthcare data will significantly reduce the burden on participants and the local site teams.

What new information will your study generate and how will this benefit patients?

RCT evidence on treatments that control serum phosphate and patient-centred outcomes, such as survival and how patients feel or function, will be able to guide policy and drug prescribing. Currently available evidence demonstrates only an association and not a cause-effect relationship between phosphate and clinical outcomes in patients with ESKD.