This global study will assess the effect of randomising dialysis sites to one of two default dialysate sodium concentrations in current practice, 140mmol/l and 137mmol/l, on major cardiovascular events and death in patients receiving maintenance haemodialysis.

RESOLVE is a pragmatic, cluster-randomised, open-label study designed to evaluate in real-world conditions the comparative effectiveness of two default dialysate sodium concentrations.

Dialysis sites will be randomised in a 1:1 ratio to a default dialysate sodium concentration of 137mmol/l or 140mmol/l. 'Default' is defined as the use of the allocated dialysate sodium for ≥ 90% of delivered dialysis sessions in the unit. All other care will be according to standard local practices as determined by the site.

Outcomes will be assessed on individual patients dialysing at those sites. Sites will be asked to consent to participation while waiver or opt-out consent will be sought for individual patients.

It is anticipated that site accrual will occur over 5-7 years with average study duration expected to be approximately 2-5 years. The actual length of the study will be end-point determined.

The site inclusion criteria are:

• Predominantly dialyses adults (≥18 years old) receiving maintenance haemodialysis
• Rates of withdrawal within the first two years of commencing dialysis for social reasons have been less than 15% for the 2 years prior to recruitment and are not expected to increase above 15%
• Has a minimum of 10 dialysis recipients at time of randomisation
• Utilises a default dialysate sodium concentration at the time of recruitment (a substantial majority of dialysis sessions are conducted with the default dialysate sodium concentration)
• Is a self-contained unit (i.e. unit patients do not regularly rotate through another unit. Brief trips by patients to a parent or other unit do not exclude a site)
• Willing to accept randomisation to either intervention (as determined by nominated Director of Unit)
• Is not a home dialysis training or support unit. [Sites that include both in-center/satellite dialysis patients and home patients may participate but the study procedures and assessments will only be conducted in the incenter/satellite component of the site].

The exclusion criteria are:

• Not able to comply with data collection methods