How to recruit for a trial


Recent research has found that there is limited quality evidence on the effectiveness of trial recruitment strategies. The majority of trial coordinators rely on anecdotal evidence to guide their recruitment decisions. I recently completed a PhD evaluating recruitment strategies for participants to clinical trials (specifically the T4DM Diabetes Prevention trial).

Three recruitment lessons

1. Radio advertising, television news coverage, and direct mass mail outs can improve recruitment. However, these promotional strategies may be expensive and time consuming to conduct, so close monitoring is required to get the promotional mix just right. Recruiting large numbers of participants through community-based strategies, such as displaying posters and attending community events, is unlikely to be successful.

2. Cost savings can be achieved by identifying parts of the screening process that can be centralised and automated. Centralisation and automation can deliver not only cost savings for the trial but also time savings for both the trial team and trial participants.

3. If screening uptake is low, SMS message reminders are a good and affordable alternative to performing telephone call screening reminders. However, it may be worth performing telephone call reminders for participants who are older or who have failed to respond to an initial SMS reminder.

Struggling to recruit?

You may be wondering what you can do to improve recruitment in your trial. Here are a few steps you might like to consider:

1. Work out what the problem is

This is simpler said that done. We often report recruitment very simply as the number of participants enrolled per month and/or per site. However, recruitment is a complex process and a simple accrual graph is unlikely to give you the information you need to pinpoint the cause of your recruitment problem/s. You’ll need to collect and analyse detailed screening and enrolment metrics or even consider conducting qualitative research to identify what is going wrong.

2. Look to the evidence

We expect evidence-based medicine from our clinicians to so it is time to practice what we preach and look to literature for evidence-based strategies to address our recruitment problems. It can be daunting to get your head around an entire body of literature but luckily there are some great resources out there to help:

  • ORRCA database: this database collects and stores recruitment- and retention-focused research and has handy filters to help you find the most relevant papers for your trial.
  • Systematic reviews: these can help you quickly digest recruitment literature in a particular area. You may like to check out the Cochrane review, or look at my review which focuses on recruitment of men.
  • Trial Forge: knowing trialists are generally time-poor, the people at Trial Forge in the UK have been looking at ways to make recruitment evidence easier and quicker for us to digest.

3. Consider conducting your own recruitment research

Once you have identified some promising recruitment strategies, you may like to conduct some research of your own to evaluate how effective these strategies are. This can help you to choose between strategies and formulate an ongoing recruitment plan. Again, Trial Forge has some excellent resources to help you plan your recruitment research.

4. Start early

First and foremost, we need to plan for recruitment success. Often it isn’t until recruitment starts to fail that we start to look at recruitment strategies. However, we know that recruitment is likely to be a struggle for around half of all trials so it makes sense to develop a basic recruitment plan before you embark on recruitment. This plan can be monitored and refined as recruitment progresses. Think ahead and set yourself up for recruitment success at the beginning of a trial.

About T4DM
I focused my research on recruitment of men aged 50 years and older, based on the T4DM Diabetes Prevention trial. The T4DM trial evaluated whether treatment with testosterone could prevent progression to type 2 diabetes in men who were at high risk of diabetes. We recruited 1,000 Australian men aged 50-74 years to the trial between 2013 and 2017. The T4DM trial is now complete and we expect to release the results of the trial shortly.


Dr Karen Bracken is a Clinical Trial Operations Lead at the CTC currently at work on the DASL-HiCAP trial