Clinical trial recruitment can make or break even the most important research endeavor. Trials depend on an adequate number of study participants to truly detect a difference in an intervention versus its comparator.
Recruitment, when done well, can enroll a study patient population that enhances study validity and accurately represents a future larger target population.
However, this undertaking is not without a great number of challenges. Below we will discuss some of the biggest challenges researchers face when attempting to recruit in clinical trials:
Study Design Issues
The study design dictates the overall methods of conducting the study, and these decisions can have a large impact on recruitment. Some of the more important study design decisions include deciding the study sample size, choosing a study design, data collection methods, and ethical principles.
Sample Size
Sample size is one of, if not the most important decision related to study design as it relates to recruitment.
Obtaining the right sample size will depend on numerous factors, including:
- The number of available study participants affected by the disease or condition
- The number of willing, identifiable participants
- The capability of a study site to process several participants
- Other statistical considerations — such as expected standard deviation, desired power to detect a difference, and desired significance level.
Adequate sample size can affect all other facets of recruitment design decisions. Sample sizes that are too small can result in studies that can be determined to be unethical or a waste of study resources, while studies that call for a sample size that is too large can result in an over expenditure of study time, money, and effort.
At the beginning of the study design period, researchers will consider a power calculation to determine the right sample size for a research question. Power is the ability of a study to determine if there is a difference between the investigative arm and its comparator(s). Doing this calculation beforehand allows the study team to budget and plan for the sample size that is needed.
The Actual Design
The actual study design is another essential determining factor for recruitment. There are a variety of study designs, such as cross-sectional, case-control, and randomized placebo-controlled, each with its own positives and negatives as it relates to recruitment challenges.
Cross-sectional designs involve measuring all risk factors and implicit variables at one time or over a single, short period of time without follow-up.
Naturally, this design can be advantageous over cohort studies and randomized controlled trials due to the lack of the need to follow up, leading to easier study recruitment and retention.
In contrast, cohort and randomized controlled trials require longer follow-up which can make recruitment difficult as it requires long-term commitments from study participants. Sometimes, study participants are less willing to consent to a randomized controlled trial due to the possibility of receiving a placebo treatment instead of the active comparator.
However, cohort and randomized controlled trials are sometimes the best study designs to investigate an intervention, so the pros and cons of recruitment challenges must be weighed beforehand when making the design decision.
Data Collection Methods
Data collection methods are another critical component of study design that can have effects on study recruitment. Trial data collection is usually collected in the form of physical observation (lab draws, measurements, etc), questionnaires, interviews, or a combination of all three. Depending on the type of data necessary to be collected, researchers will have to make practical considerations related to cost and logistics.
For example, some interviews and questionnaires can be completed remotely or over the phone without the need for physical, in-person assessment, while blood draws almost always require a face-to-face follow-up appointment. In-person follow up can sometimes be an obstacle to patient recruitment as some patients simply do not have the time or resources to commit to these appointments.
Ethical Principles
Finally, ethical principles and their effects on recruitment weigh heavily on study design decisions. Most studies will experience a normal, given amount of recruitment decline after eligible patient identification. Patients must consent to participating in a trial by providing informed consent and patient confidentiality agreements.
Additionally, these consent forms include information about the possible risks and harm that can occur because of their participation in the trial. Some patients are not willing to accept these risks and therefore decline to consent. Researchers must anticipate a certain number of declined consents in advance of their recruitment efforts.
Choosing the Right Demographic
Choosing the right group of patients to participate in a clinical trial is an absolutely critical study design decision that can profoundly affect recruitment efforts. The right sample group of patients in a clinical trial is one that is representative of the final target patient population in that they are generalizable and representative.
As an obvious example, a clinical trial that recruits a group of 20 elderly men would not be generalizable or representative if the intervention was examining the efficacy of a new birth control method for women of childbearing age.
Generalizability can be deceptively hard to achieve in clinical trials. If an intervention is targeted to benefit anyone in the United States, for example, study participants should be included from both urban and rural areas to be truly generalizable.
This can be difficult when it comes to recruitment because a lot of different recruitment methods in different demographic areas with varied infrastructure and population density considerations must be had.
The right patient demographic must also be representative for a clinical trial to be successful.Representative study samples assist generalizability, but they also have their own considerations as it pertains to recruitment.
Many studies meant for investigative treatments are intended for use in the general public which includes ethnic minorities, the cognitively impaired, and other vulnerable patient populations such as the homeless or prisoners. These special populations should also be carefully represented in recruitment efforts to maintain a representative sample.
Beyond generalizability and being representative, picking the right patient demographic has other challenges when it comes to recruitment.
Recruiting normal control patients in randomized control studies, while simple on the surface, can present difficulty at times due selection bias.
It can be easy to select healthy volunteers as controls for studies out of geographically close friend groups, coworkers, or community members, but these convenient study participants may not reflect the diseased patient population accurately.
The normal control patients must be selected out of the same study population as the diseased patients in order to control for numerous environmental, societal, and geographical biases.
Recruitment Techniques
Once a clinical trial has achieved adequate study design and is targeting the right patient demographic for recruitment, recruitment techniques must be deliberated. There are a vast number of different recruitment techniques, each with its own set of costs and benefits.
Picking the right technique can depend on many factors such as the research question, study design, and available study resources.
Before picking the recruitment method, researchers must understand there is a participant and investigator perspective on each side of the recruitment effort.
Participants tend to use a personal cost-benefit analysis when they decide to participate in a study as they consider direct personal health benefits, societal benefits, and other incentives such as financial gain if the study is compensated. Investigators will contemplate details about the study such as scientific integrity and being respectful of the research process.
Finding a middle ground between the potential participant and the investigator is key to successful recruitment.
Finally, the actual recruitment techniques must be evaluated. Beyond simply reaching out to potential participants, there are numerous different strategies to consider.
The mode of communication is key when attempting to perform a professional correspondence with a potential study participant. Phone calls, emails, and written letters are all important communication techniques that have shown success in trial recruitment.
A face-to-face recruitment strategy should also be considered, and some evidence shows that this technique is the most effective, especially when performed by a physician or healthcare provider that the potential participant trusts. Some clinical research organizations (CROs) have a wide variety of physicians in their network that can recruit patients for clinical trials using this method.
Other evidence suggests that assertive tracking, or not giving up after the initial recruitment attempt, can be very important. Researchers should use a different communication technique from the initial attempt to try and reach potential participants while still respecting the participant’s free will and privacy.
Use iProcess for Clinical Trial Recruitment
At iProcess Global Research, you can expect to work with exceptional teams that have years of experience in cutting-edge research. As experts in clinical trial staffing and consulting, your clinical trial recruitment efforts can be streamlined to perform at a high level of quality and competency. Our team of recruiters are dedicated to supplying optimal solutions for clinical research sites across the globe.
iProcess not only supports patient recruitment and engagement, but they also handle clinical trial monitoring, medical affairs, and data management and biostatistics.
Contacting iProcess is quick and easy to request a quote or perform a free feasibility request.
Sources:
Challenges in recruitment and retention of clinical trial subjects | PMC
Clinical trials: the challenge of recruitment and retention of participants | PMC
