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Feasibility Testing

Professor Wright explains the concept of feasibility testing.
Welcome to this brief video on feasibility studies.
Just to remind ourselves the MRC guidance puts feasibilities after developing intervention but before we do the evaluation, the definitive trial. So interestingly there’s no international accepted definition of a feasibility study and it’s frequently used interchangeably with pilot studies but both terms are commonly used when definitive trials were failed and people said actually this was a pilot, there’s a feasibility, we’re trying to learn about it, we didn’t expect to show an effect or we didn’t recruit as many patients as we thought we should do or what we expected to.
So for the purpose of this course uh we’re going to use the concept of feasibility study being something to test the research process, but start to develop the research process, there’s nothing about hypothesis testing it’s purely about; is our plans for the research or are there plans of research feasible and can we refine them. So there should be nothing there about showing the intervention works at all.
And then the pilot is kind of the next phase and it can actually be within the main trial as an internal pilot or outside of it but what you’re doing there is the feasibility study says this is what the trial should look like, you then run it small scale to see whether you’re right and whether you will recruit as you expected and whether the intervention may look the same across all sites once you start to expand it.
Feasibility study is usually based on small numbers, pilot studies are much larger numbers but not nowhere near as big as a definitive trial so you’re kind of building up and scaling up as you go through and it’s only the definitive trial where you test the hypothesis so that’s the only time where you actually say right let’s see whether my hypothesis works or not at neither the feasibility or pilot study stage should you be doing this. So let’s look at what a feasibility study includes, - and it’s more than this, but this just gives you an oversight, we’ll give you a session on this - uh - in week week three it will be.
So uh first of all we need to see is the population size for our study sufficiently big enough so once we do the searches on databases or we run it on the ward look at our records and see how many people are coming in. Are there likely to be enough people for us to test our intervention then how do we best identify them and how do we best recruit them, to what stage of the care process or do we do it by post or do it by face to face and who’s the best person to do that and where and when.
Once we’ve got all that kind of worked out you know what’s what is our recruitment rate, exactly how many patients can we you know reasonably expect to recruit. And one of the things I was told was uh when I was managing that panel was anything more than a couple of patients a week is probably unfeasible. So anybody running a definitive trial saying “I’m gonna recruit five-ten patients a week from one site or one setting”, maybe setting themselves up to fail and the feasibility study will enable you to work out what is reasonable and what you can do with the resource you’ve got.
And it may not sound a lot, but if you’ve got 10 sites or recruiting one or two patients a week then actually you know you will quickly build your numbers up. Once you’ve got your recruitment you need to make sure that your service or your intervention is going to be fidelity delivered i.e everybody everywhere is delivering it in a similar sort of way.
And so you need to very often do some training for that or at least some competency assessment to make sure that people are all doing exactly kind of what you want them to do so that you’re not getting half a service over here quarter over here and a double service in another place because then you really don’t know what’s causing the effect you’re seeing. You also need to check your data collection processes; can I get the data from the records that exist? Is it suitable quality? What do I need to do to get the data from the patients? Will a post out to them work? Will it be electronic?
And all these things again we’re testing at this stage so when we run the main trial we know what the best processes are. We then at the end of that can look at the data we’ve got for our outcome measures and start to think about whether that data is going to be good enough for the main trial, also start thinking about which of these outcome measures do I want to keep? And which one actually can I jettison at this stage because they’re not going to help me with my final decision and answering my final hypothesis.
Running alongside any trial you have what’s called a process evaluation and this is where you try to understand the processes that are going on so you can see why things worked and why they didn’t work. And you can understand the mechanisms of action so what parts of the intervention created the effects that you saw or what part of the intervention did nothing at all, and that again we’ll cover later on in the course but actually that, you can again require some thinking and requires a bit of creativity and at the feasibility stage you can test it you can develop it test it refine it without worrying about getting it wrong because it’s not for testing a hypothesis.
And then as from the health economist perspective at this stage they really want to make sure that are we going to capture all the costs have we identified all the costs associated with this intervention is there anything unexpected happen, any unexpected increase in burden, in workload for anybody as a result of what we’re doing here. And have we got a good way of measuring them so we can get an accurate estimate at the end of the trial. And the secondary focus of a feasibility study is is checking that your intervention is acceptable and practical and it’s not just for the healthcare professionals but for the patients as well.
If it’s found to be not practical at this stage then you know it’s never going to be rolled out so if it’s not acceptable people aren’t going to buy into delivering it or receiving it. So at the feasibility you can test all these things and provide some reasonable evidence so at the end of it, you can say “yes we should now be able to go to a trial and this is how it should look”.
So to summarise the terms feasibility study and pilot are used interchangeably but there’s no real international definition and for this for this uh course we’ve provided clear definitions. But what I’ll say now to you as an early career researcher, please don’t run a trial, let it, find it fails, and then say well let’s rename it a “feasibility” or a “pilot” because the meaning, actually, these elements in the process they have their own element their own stage and therefore people should use them as such and they have such different objectives that they really can’t be swapped between the two.
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