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Feasibility studies

Feasibility Studies: preliminary research to identify any challenges and risks to the conduct of your main trial

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Ensuring a randomised controlled trial runs smoothly can be a challenge, even for the most competent of research teams. Trials can involve complex protocols, require the collection of intricate clinical data, and may involve recruiting from a population of patients at a sensitive time in their lives.  Feasibility studies are thought of as an investment towards a main trial; they aim not only to determine if your main trial can be done, but to contribute meaningful insight of any challenges so that you can then mitigate for such risks in the design of the main trial. Feasibility studies explore issues which can either: relate to, for example, the refinement and delivery of the intervention, the setting, conduct, and length and nature of information asked in a trial; or to ensure the main trial has the potential to change practice and is acceptable to patients and health care professionals.

Often the first question to ask is: Is a feasibility study required? Before rushing into an application for funding for a feasibility study, think carefully about what your main trial might look like. In a grant application, it is beneficial to state the main research question, if possible using PICO (Population, Intervention, Control, Outcomes), and list any main trial assumptions and gaps in the plan for the trial. You should review the literature for previous trials similar to your intended main trial to understand if there were any issues with the conduct of the trial. Did previous trials complete on time? Did they have any major protocol amendments or require further funding? What were the discussed challenges, and what kind of solutions may overcome these? If there is remaining uncertainty necessitating a feasibility study, it is the gaps in the plan for the main trial that will form the basis of the feasibility study aims and objectives.

As NIHR’s Research for Patient Benefit funding programme guidance notes point out, feasibility studies should not attempt to evaluate the effectiveness of an intervention.  This is the primary question for the main trial to answer. The argument is that feasibility studies will be too small to give any definitive evidence of effectiveness or efficacy. The discussion of any observed effectiveness from the feasibility study could be misguided, and undermine the need for a sufficiently powered and well-designed main trial.

It’s not always obvious which aspects your feasibility study may examine. Feasibility research may encompass a broad range of issues from recruitment to follow-up, for example:
  • estimating rates of recruitment and retention, and adherence to treatment;
  • investigating the feasibility of recruitment and consent processes;
  • exploring patients’ and health professionals’ perspectives and willingness to be involved;
  • weighing the burden of participation and acceptability of assessments;
  • estimating parameters such as standard deviations of outcome measures to allow sample size calculation for a full-scale trial.
But every study is different, and you should consider each on its own terms. Here are two examples of feasibility studies that were supported by public funding:


1. The PROTECT study

Donovan J, et al. Health Technology Assessment 2003;7(14).
The PROTECT study explored the feasibility of conducting a main trial to evaluate three treatments for prostate cancer. The treatments for consideration were: 1) radical prostatectomy 2) radical radiotherapy and 3) non-radical option involving monitoring that is variously called ‘watchful waiting’, ‘conservative management’, ‘monitoring’ or ‘surveillance’.
Previous trials, for example the US Prostate Cancer Invention Versus Observation Trial (PIVOT) and UK MRC PR06 studies, experienced considerable challenges, including the source of patients with true localised disease, the patient preference for particular treatments, and the high rate of 10-year survival in men with local prostate cancer.  This established the need for the PROTECT feasibility study to 1) explore the feasibility of ‘case-finding’ in the community as a source of patients, 2) determine the most efficient and effective design for a main trial of treatments, 3) undertake a randomised feasibility study of potential recruitment strategies and 4) pilot outcome measures and procedures for the main trial. They evaluated the acceptability of randomising participants into either a 2 or 3 arm RCT, developed and selected the most suitable outcome measures, compared the recruitment rates of research nurses and consultant urologists, considered if sufficient numbers of recruits could be secured by a programme of ‘case-finding’ in the community, and tested procedures for conducting the major multicentre trial. The PROTECT study gave a comprehensive analysis of the feasibility of the RCT across a number of issues.  An example of the PROTECT findings is that ‘watchful waiting’ to describe one treatment protocol had unexpected negative connotations to participants, and ‘active monitoring’ gave participants more confidence they would not be neglected if randomised to this treatment arm.

2. The KORAL study

Mowatt G, et al. Health Technology Assessment 2010;14(5).
The KORAL feasibility study focused on one particular objective, which is the acceptability of placebo surgery as the comparator treatment in a large definitive trial. The main randomised controlled trial would evaluate arthroscopic lavage (a surgical technique to wash out contents in a joint space) for the management of osteoarthritis of the knee. A placebo surgery, or ‘sham surgery’, was considered the most ideal control treatment to minimise bias in the trial, but posed challenges with the acceptability and feasibility of randomising patients to sham surgery. KORAL undertook focus groups and also surveyed surgeons and anaesthetists. They concluded that a main definitive trial with a sham surgery arm would be extremely difficult to undertake. The recommendations from the KORAL feasibility team suggest further research into 1) the usefulness of decision aids to support informed consent for such a placebo-controlled surgical trial, 2) the effects of different terminology for describing the control treatment, such as placebo, sham and dummy, 3) the surgeon–anaesthetist partnerships when planning clinical trials, especially trials including a placebo surgical arm and 4) the influence of ethical perspective of individuals participating in the trial. The findings from this feasibility study have also informed the best practise for trials in other populations where sham surgery as a control arm is considered.


Which NIHR programmes fund feasibility studies?

The Research for Patient Benefit (RfPB) programme will fund feasibility studies that cost up to £250,000. Other NIHR programmes including Health Technology Assessment (HTA), Efficacy and Mechanism Evaluation (EME) and Public Health Research (PHR) will also fund more expensive feasibility studies, if the next proposed study is within remit of the programme and there are clear progression criteria. A feasibility study might also be a Work Package within a wider programme funded by a Programme Grant for Applied Research (PGfAR) or a Programme Development Grant (PDG). The Public Health Intervention Development Scheme (PHIND) within the Medical Research Council funds the development of public health interventions, including developing theory, modelling process and outcomes, and developing procedures and protocols, though they recommend that “pilot testing or stand-alone feasibility studies” be submitted to the relevant NIHR programme.
Lauren Bell
RDS London
Queen Mary University of London

With input from: Claire Chan and Richard Hooper, Queen Mary University of London
Feb 2017