Ensuring On-time Patient Recruitment in Clinical Trials

January 29, 2021

Patient recruitment is one of the trickiest and most time-sensitive aspects when conducting a clinical trial. Problems with patient recruitment and retention accounted for 80% of trial failures in the U.S.¹, and lack of available patients is frequently listed as a major culprit of delays – with all the squandered resources this entails.

In this article, we will examine some of the reasons why finding and attracting patients is so hard, as well as some of the measures we take to prevent this.

What Makes Patient Recruitment So Complex?

The patient recruitment process starts with planning, and then moves to include screening, selecting and retaining them. Such a long process offers several possible bottlenecks that can derail patient recruitment and complicate the process. These are usually related to:

- Site selection and characteristics

The site location, and the characteristics of the region in general, will determine your initial patient pool. When selecting a site, make sure to acknowledge:

  • The expected number of people in the area with the required diagnosis (and, to a lesser extent, the total population of the area).
  • The quality of medical services and public transport networks in the area, which will expand or restrict your catchment area.
  • The site profile, including their experience with similar clinical trials, the existing services available for the target population, and their personnel resources
  • The presence of similar clinical trials that may compete for the same patients.

- Study design and protocol

The trial design matters enormously when defining the “ideal patient” for each trial. 

If inclusion and exclusion criteria are too narrow, you may not be able to find enough patients. Invasive screening tests or a high number of tests could influence the patients’ readiness to enrol into the trial.

- Investigators’ motivation and experience

When choosing an investigator, finding the “perfect match” will pay off in the long run. An ideal investigator is one who has enough time, experience in clinical trials, and expertise with the condition or illness being treated. Professional sites with experienced, dedicated teams have consistently proved to follow patient recruitment projections better.

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How to improve patient recruitment in clinical trials?

Keeping the aforementioned factors into account, there are several strategies that can help you run the patient recruitment process in the most efficient way possible. 

  1. Think of the process holistically

Furthermore, it is important to have someone to take ownership of the entire process throughout the study. It is relatively easy to disconnect the different clinical trial recruitment strategies, for example, by leaving screening to someone who is collaborating with early implementation, and assigning recruitment efforts to someone else later. Instead, you should aim to have one manager in charge of this one process. 

  1. Make it a priority of the protocol feasibility studies

Having a well-thought-out, early clinical trial feasibility study is perhaps the most important step of the planning stage. This stage will define the methods the study will use and select all the starting sites – which in turn, will directly affect the number of patients available to you.

At this stage, you should address:

  • The patient profile required by your trial
  • The profile of the site where patients will be treated or observed.
  • The difference between the study protocol and the current local standard of care
  • The requirements set by local authorities and ethics committees
  • The type of advertising materials or information leaflets you may use during recruitment if any.
  1. Use a “tight funnel” during the screening and initial enrollment process

Investigators and researchers involved in the biomedical industry often jokingly quote “Muench’s Third Law”² when asked about patient recruitment strategies in clinical trials. This law states that, in order to get the number of actual eligible patients available, you should take the number that you think you have and divide it by 10.

Although exaggerated, this describes a common trend in many clinical studies: in order to ensure that they will have enough patients ready before the deadline, many project managers use a “wide funnel” and attempt to enrol as many people as possible, hoping some will stick until the end:

Under this tactic, if you just approach and screen 1000 people instead of 100 (circle A), you increase your chances of having 10 people left by circle C.

However, this is a very inefficient approach, as it wastes resources, increases the staff’s stress levels, and may actually cause additional delays. 

Each potential participant that you approach, inform about the study, and screen takes valuable time and resources. If your study protocol requires longer or extensive testing during screening, you may accidentally create backlogs in reporting. 

Finally, any patients who fail the screening stage may feel burnt out and become less eager to enrol in any future studies.

Instead, focus your efforts on approaching only the ideal patients from the start: 

  • Train your investigators so that they can properly identify good, motivated candidates.
  • Work closely with local physicians and other allied health professionals, to ensure their referrals are useful.
  • If available, use electronic medical records to “pre-screen” candidates before spending time or resources on testing.
  • Consider using digital patient recruitment tools, especially social media advertising. This allows you to address a specific demographic directly, and use online surveys for pre-screening.
  1. Consider alternative recruitment schedules

Depending on the type of study you are conducting, consider adjusting your recruitment schedule to mitigate the impact of those who drop-out from the study. 

For example, if you are conducting large-scale pharmacological studies that requires a large number of healthy volunteers, try a “batch model”. This will allow you to have more subjects ready for enrollment in case the study needs to be expanded later on³.

The “batch” strategy can also be very useful for studies with critically-ill patients who may deteriorate rapidly.

In these cases, your team should also try to get a participant’s consent ahead of time, and have them “pre-enrolled” in case their health worsens.

Naturally, the type of adjustments you can use will depend on the type of study. At Dokumeds, we can identify these possibilities during the feasibility or protocol drafting stages.

  1. Keep the patient’s experience in mind

As a general rule, the more comfortable a patient feels while being screened or enrolled in a clinical trial, the least likely he or she will be of dropping out. Depending on the type of study, you may also need to take into consideration the patient’s immediate family or their caretakers.

Whenever possible, try to:

  • Minimize the “patient pathway”, or the steps, appointments, and places that a patient needs to visit before they can become enrolled in a trial.
  • Seek non-invasive tests, both during the initial screening or during follow up.
  • When possible, minimize the patient’s commuting inconvenience or expenses. This can be done by providing free travel or by setting up a reimbursement process.
  • Ensure that any appointments or tests can be scheduled at convenient times.
  • Use “remote visits” or online symptom monitoring for patients who are at home.
  • Use video calls to explain the study’s process, or to get additional consent beyond a simple signed form.

Ultimately, an efficient and non-intrusive recruitment process will keep the process comfortable for patients, while minimizing the workload for clinicians and staff. In this way, the overall process will run smoothly, on-budget, and without missed deadlines.

  1. Keep investigators engaged

Figuring out how to improve clinical trial recruitment will require building and maintaining the investigators' trust. This is an ongoing process.  A good peer-to-peer communication system will allow them to notify any issues arising with patient recruitment and retention quickly. It will also speed up communication between sites. Perhaps more importantly, keeping these communication channels open will help them feel heard and maintain their engagement with the study for a longer time. 

As a CRO with a strong focus on medical services, at Dokumeds, we believe that the most efficient strategies are those designed early. Learn more about managing patient recruitment with our Webinar: Accelerate your Trials with Efficient Enrollment. Alternatively, book a call with one of our consultants.


  1. Clinical Trials AReNA Clinical Trial Delays: America's Patient Recruitment Dilemma. 2012. Jul 18, [Last accessed on 2019 Dec 05]
  2. https://www.sciencedirect.com/science/article/pii/S0895435614004132#bib4
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2878987/


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