The Delphi process has been applied to identify topics of importance and establish consensus for trials methodological research priorities. ‘Methods to boost recruitment in trials’ were considered the highest priority, closely followed by ‘Methods to minimise attrition’ and ‘Choosing appropriate outcomes to measure’. This group of Directors of UKCRC registered CTUs also reached consensus that methodology research into ‘radiotherapy study designs’ and ‘low carbon trials’ should not be priority areas. Whilst this work is informative in providing broad topic areas to guide future research, specific research questions within a particular topic have not been prioritised. A further study using similar methodology to the current study could be undertaken to help identify and prioritise specific research questions.
Examples from the literature where consensus methods have been applied in clinical research include identifying gaps and prioritising trials in colorectal cancer , defining national research priorities in bone metastases , and work undertaken by the James Lind Alliance to determine important questions about treatments where uncertainty remains . However, to our knowledge no priority setting exercise using rigorous consensus methods has previously been undertaken to guide methodological research in clinical trials. Within the growing literature on the elicitation of opinion and the development of core outcome sets in clinical trials, the range of consensus methods that have been applied include expert panel meetings , Delphi surveys , Nominal Group Techniques , focus groups , individual interviews  and individual questionnaires . The practical difficulties of getting the CTU Directors together for a face-to-face meeting, and ensuring that each participant had the opportunity to contribute equally to the consensus process, made the on-line Delphi approach the preferred method for this particular priority setting exercise. Further rounds of the Delphi process may also have identified additional consensus priorities but this would have created a further burden for CTU Directors who are frequently targeted for on-line surveys.
Directors of UKCRC registered CTUs were selected for this exercise as they have relevant, and established, expertise in designing and running clinical trials, as well as being knowledgeable about the current landscape of methodological research. Ensuring that trials methodological research focuses on topics that meet the needs of this group is vital - all too often methodology is developed without considering the end-user, or the demand for such research, thus limiting the scope for practical implementation. It is also worth noting that five out of eight HTMR Directors are also CTU Directors and participated in the Delphi process. Further work with additional stakeholder groups such as clinical trial investigators, other methodologists, trial funders and policymakers, albeit with an anticipated divergence in perspectives, would be worthwhile and may show different preferences for methodological research priorities.
Overall, 41 (85%) of the registered CTUs participated in at least one of the three completed rounds. However, whilst this is a good response rate compared to previous on-line surveys undertaken with this stakeholder group, only 12 (25%) CTUs responded to all three rounds and only 18 (38%) responded to both rounds two and three. The seven CTUs that did not respond to any round covered a range of geographical areas and clinical specialties which were largely represented by the responding CTUs. Several reminders were sent using direct Email contact and it seems reasonable to assume that lack of time was the main reason for non-response, rather than substantially different or opposing views.
Of course, as has been noted by others, ‘the output from consensus approaches is rarely an end in itself’ , but this prioritised list of research topics provides a robust guide for trials methodology researchers and could help to focus resources more appropriately. Furthermore, the three identified priority areas are represented across six working groups that have been established by the MRC-funded HTMR network (Evidence Synthesis, Stratified Medicine, Outcomes, Recruitment, Trial Conduct, Adaptive Designs) to undertake projects on specific issues in methodology, including the provision of workshops, development of guidance papers, and liaison with stakeholders. Results from this work have been shared with the joint MRC-NIHR methodology research programme panel which funds investigator-led and needs-led research on methods development to underpin a number of areas including clinical trials.