What if a simple shift in perspective could drastically improve patient recruitment in clinical trials?
That’s exactly the topic I explore in my previous post, What Healthcare Reform Can Teach Us About Patient Recruitment. I explained how a systems approach to healthcare improvement has been extremely successful in the broader healthcare system, and I explored how that same approach can benefit clinical operations, particularly with regard to patient recruitment. Here I build on what was discussed previously, so I suggest you read my patient recruitment systems post before proceeding.
A systems approach to patient recruitment can be tackled from a variety of angles, but here I’ll focus on a simple metaphor to help us think about patient recruitment in a way that is not typical for clinical trials. And I’ll explain why this metaphor can be particularly powerful for sponsors and CROs who want to improve their enrollment timelines.
When we talk about patient recruitment challenges, discussion often revolves around failures that occur at the site level. Though discussions about site failure can be useful, these discussions can conceal other important factors contributing to patient recruitment challenges.
The Leaky Pipe Model of Patient Recruitment
Instead, think about patient recruitment systems as a pipe between a potential recruitment pool and subject randomization. Many things occur between these endpoints, and as these things occur, prospective study subjects are lost through “leaks” in the pipe.
The illustration below is of a potential patient recruitment system in a clinical trial. This system is not representative of all patient recruitment systems, nor does it detail every step in the process. But it illustrates common processes in a general manner.
As you can see, I’ve highlighted the end of the pipe, which is where a research site has contact with prospective participants. This highlighted portion of the pipe is where sponsors often look for system failures when they don’t hit enrollment deadlines. But as the illustration demonstrates, many things occur upstream of the site, and potential subjects are lost during these upstream steps as well.
Clinical Trials Awareness and Attitudes
For example, the first step on the illustration relates to public awareness and attitudes about clinical trials. “Leak” is perhaps not the best word to describe patients lost at this step. Geyser would be a more accurate description.
The Center for Information and Study of Clinical Research Participation (CISCRP) published the following statistics with regard to public awareness of clinical trials:
- 74% of respondents say they have no ‘real’ knowledge of the clinical research process.
- 98% of respondents do not know where and how to identify and evaluate appropriate clinical studies for patients diagnosed with cancer and other chronic diseases.
And at a recent forum hosted by the Institute of Medicine, multiple industry professionals cited public mistrust of clinical trials as a significant barrier to patient recruitment.
Lack of awareness, combined with a general mistrust of clinical trials, prevents many prospective study participants from continuing on the patient recruitment pipeline. CISCRP does a lot of work in this area, but one organization can only accomplish so much. Sponsors and CROs, for the most part, continue to focus on protocol-specific recruitment rather than general clinical trials awareness initiatives.
Patient awareness is just one example of the potential for repair of upstream leaks in our patient recruitment systems. Yet the clinical research industry continues to focus on site systems as a point of patient recruitment failure.
Sites are at the very end of the patient recruitment stream and will continue to face recruitment challenges as long as the upstream process leaks are not fixed.
The Leaky Pipe Model of Patient Interest
Though a high-level review of patient recruitment processes is helpful, patient recruitment should always be considered from the individual patient view as well. In this case, we can use the leaky pipe model to understand where flaws in our systems have the potential to “leak” patient interest.
When patients lose interest in a study, they may cite one reason for that lack of interest or simply leave their explanation at “not interested.” But the human decision-making process if far more complex, and decisions regarding study participation are the result of a complex calculus of risks and benefits, many of which even the patient cannot fully articulate.
A screen failure may be captured as “not interested” or “too far from site” on a screen failure log, but patient decisions rarely hinge on one factor. Because patients do not articulate their full decision-making process, sites, CROs, and sponsors often remain unaware that particular processes are “leaking” patient interest.
As an example, check out this illustration of a hypothetical patient’s movement through a hypothetical patient recruitment system.

Though patients often cite one reason for lack of interest, the decision-making process is far more complex.
As the patient moves through the trial’s patient recruitment processes, he has the potential to lose interest at several steps along the way. Once the “leaks” in interest build up to a point where the cost and risk of participation are greater than the benefit, that patient will decide not to participate.
All systems are subject to some variability, so each patient’s experience moving through a patient recruitment system will be different. And each patient’s view of that experience will vary according to his unique perspective.
Fixing Recruitment Leaks
The variability of a patient’s individual experience and perspective, combined with the invisible nature of many interest leaks, makes it difficult to identify problematic processes. For this reason, we need to be proactive about anticipating potentially problematic areas before and throughout a trial.
Once a potential leak is identified, we have 4 options:
- Leave the leak as is.
- Attempt to repair or lessen the leak.
- Leave the leak as is, but combat the potential for lost interest by providing additional benefits of participation.
- Lessen the leak, and combat potential for lost interest by providing additional benefits of participation.
The Leaky Pipe Model of Patient Retention
The leaky pipe model of patient interest can also be extended to retention. Here’s an illustration of a hypothetical patient’s experience after enrolling in a study.

This illustration represent trial systems that create lost interest for a hypothetical enrolled subject.
The patient has an initial reservoir of interest at randomization, and a series of clinical trials systems create lost interest for this patient over the course of the study.
Let’s pretend this participant decided to drop from the study. Do you have any guesses as to what reason the patient will cite when he drops? How do you think his decision to drop will be captured on the enrollment log? I can’t say, but I am relatively certain that his full decision-making process will not be captured. For this reason, many retention leaks will remain invisible to sponsors, CROs, and sites.
Fixing Retention Leaks
Just as in the previous example, we should proactively anticipate retention leaks and attempt to fix or mitigate them where possible.
When you look at the burdens illustrated in the graphic above, do you think a study-branded tote bag will sufficiently combat these interest leaks? I doubt it. It would be far more effective to directly alleviate burdens being placed on the patient and/or provide the patient with something of more meaningful value. (Note that I used the word value and not cost, which is an important distinction.)
Some burdens are easy to remedy (time and travel expense), while others are far more difficult. Medication dosing, for instance, will be determined by the profile of the investigational product being tested. Though the sponsor may not be able to change a dosing schedule, it can consider ways to ease the inconvenience of dosing.
You might look at the leak of this patient’s difficulty getting off of work for appointments and think this burden is not the result of a clinical trials system. But it is. The system in place requires that patients physically visit a research site during normal working hours. Sponsors like Pfizer are working to ease this burden through at-home clinical trials. And many sites ease this burden by allowing subjects to schedule appointments after hours.
The Power of the Leaky Pipe Model for Patient Recruitment and Retention
Improvement of research site systems is just one piece of the patient recruitment puzzle. In fact, upstream systems at the sponsor and CRO level have far more potential to impact patient recruitment than the systems of sites.
No matter how much a site excels at recruitment, that site’s prospective subject pool will always be limited by upstream systems created by sponsors and CROs. As discussed in my previous post, telling sites to do a better job of recruitment will only accomplish so much. Sponsors and CROs who thoughtfully examine the effect of their systems on patient recruitment and retention can dramatically improve enrollment timelines.
So what do you think? Am I totally wrong on this? How do you think we should think about patient recruitment systems? Do you have any suggestions for improvement? Put your thoughts below.
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