It is difficult to robustly compare the effectiveness of a treatment using observational data, as it is rarely possible to capture (and adjust for) all of the factors that determine why one person receives one treatment and another person doesn’t. However, the ideal way to make such comparisons, in randomised controlled trials, has become so expensive over the last few decades that very few research topics can justify such a study design. Utilising the infrastructure of the UK Renal Registry and the trial methodological expertise of the NIHR Bristol Randomised Trials Collaboration / BTC Bristol Trials Centre, we are now leading a number of exciting randomised controlled trials aimed at answering important clinical questions.

These are pragmatic trials testing a complex intervention in a real-world setting, such as:

• Prepare for Kidney Care – which is aiming to determine the relative effectiveness and cost-effectiveness of preparing for responsive management versus preparing for dialysis on quality adjusted life years after three years in multi-morbid, frail, older patients with advanced CKD. www.bristol.ac.uk/population-health-sciences/projects/prepare-kc-trial/ 
• The High-volume Haemodiafiltration vs High-flux Haemodialysis Registry trial, which is aiming to determine the relative effectiveness and cost-effectiveness of high-volume HDF compared with high-flux HD on non-cancer mortality and hospital admission due to a cardiovascular event or infection. www.bristol.ac.uk/population-health-sciences/projects/h4rt-trial/

Both of these trials are benefiting from embedded QuinteT Recruitment Intervention to optimise recruitment and retention through embedded qualitative research that feeds back to the trial team in real-time. (4) They also examine the cost-effectiveness of the interventions with expert input from Health Economics at Bristol. www.bristol.ac.uk/population-health-sciences/centres/healthecon/