Embedding randomised controlled trials in renal registries

Traditional randomised controlled trials that rely on research staff to collect data are becoming increasingly expensive. As a result, the number of interventions that can be scrutinised for effectiveness will be limited. Further, while results from such trials have high internal validity, they will have limited external validity – generalisability to the real-world population. One solution is to adopt a more pragmatic approach and embed randomisation into routine healthcare databases such as registries. There are a number of ways that this can be done. Most commonly, registries simply provide extended follow-up to traditional explanatory trials, but with the necessary permissions, more novel approaches are possible. Registries can be used to identify potentially eligible participants, provide the baseline data and provide all of the follow-up data. Proportionate to the risk associated with the intervention, routine healthcare databases can also provide some of the safety monitoring data, greatly reducing the burden and cost of the trial. There are of course challenges to running trials in registries. Careful attention must be paid to the lawful basis for processing data collected for non-research purposes. Data quality needs careful consideration when considering outcomes, fidelity and safety monitoring. While the sample size and event numbers may be higher, there may be some loss of precision which needs incorporating into sample size calculations. To illustrate the opportunities and challenges a number of reported and on-going registry trials are presented.