Study Participant Retention in Clinical Trials

When it comes to successfully completing clinical trials, participant recruitment is critical. Equally as important, and no less challenging, is keeping these study participants enrolled in the trial for the duration of the study. Because the recruitment process is often a long and laborious exercise, participant retention is important, as dropouts can lead to increased trial costs, longer trial duration, less statistical power for the study and the validity of the results, and low staff morale. Ultimately, poor clinical trial retention is likely to impede the evaluation of retinal interventions and further prevent efficacy in clinical development.Cramer JA. Subject recruitment and compliance issues in clinical trials. Epilepsy Res Suppl. 1993;10:211-222.

Barriers to Participant Retention and Retention Strategies

Many study participants enter a clinical trial because they are seeking a potential treatment for a disease that has limited or no treatment options. It is no doubt, then, that these subjects will have certain expectations of the trial or, at the very least, high hopes. In order to help your study participants make an informed decision about whether to enroll, a detailed discussion should take place prior to enrollment. The more information your study participants have going into a trial, the more likely they will be able to keep their expectations in check and stay enrolled for the duration of the study. This initial conversation is essential because, if at any point, the trial does not match your participant’s hopes or understanding of the trial, the dropout risk increases. It is also important to outline the study visit by visit and thoroughly explain what tests or procedures will be conducted so that the study participant is aware of what will be required throughout the study. Additionally, providing educational materials on both the disease and intervention will allow the study participants to familiarize themselves with the trial and reduce concerns. Encourage your participants to spend time with these materials and ask questions for clarification. Although there may be unexpected, uncontrollable circumstances that arise throughout the trial, most other issues or concerns can be resolved with open and honest communication.

Because many diseases of the back of the eye are attributed to the aging process, many of the study participants in these clinical trials are elderly. And where do our grandparents go during the winter? Somewhere warm. Those study participants who live in Florida or Arizona during the winter months and in the cooler north during the summer months are what we like to call “snowbirds.” If there are members of this snowbird group who are interested in participating in a study, the sponsor/clinical research organization should establish a process whereby investigators participating in the trial are able to see these study participants throughout the study while they are living in each location. This requires that the participant’s source documents be transferred to each investigator throughout the trial. Although this may involve extra work for sites, it is critical to recruitment and reducing dropout rates for these participants.

You may also want to suggest that your prospective participant bring a family member, friend, or companion to the initial visit to review the informed consent and study details. The informed consent process is among the most critical aspects of human participant protection throughout the clinical trial. For retina studies in particular, caretakers will likely be a significant part of the clinical trial process, as they will be taking the participant to and from study visits, unless transportation can be provided otherwise. Making sure both the participant and the caretaker are fully informed and onboard with the study procedures and visits will help to facilitate a smooth and successful clinical trial experience.

Unfortunately, even very thorough pre-enrollment strategy discussions cannot fully prepare every participant for sometimes very rigorous clinical trials. Once the study has begun, study participants may describe difficulty adhering to the protocol specifications, such as the frequency of visits or the dosing schedules. If the participant feels as though he or she can express any concerns freely and receive empathy and understanding in return, he or she may be less likely to abandon the trial and try to work through any issues that arise. It is often advantageous to have a limited number of staff working with each participant to help build a more personal connection and rapport. Seeing the same staff members at each visit will help to promote a sense of familiarity and comfort. Study staff personnel can become pivotal in the study’s success, especially if the participant feels comfortable enough to vocalize concerns, so it is important to make sure that each participant has the means to communicate with the study personnel during the trial.

Today’s technology also offers a new option to assist with subject retention and study adherence, with the proper institutional review board approval. Messaging services now provide text, email, and phone reminders that can help subjects stay on track. For example, visit, compliance, and dosing reminders can all be sent by voice, text, or email.

Study participants are Volunteers

Finally, it is important to remember that these study participants are volunteers, so they ultimately have the option of leaving the study at any point. To that end, an atmosphere that allows study participants to feel comfortable and valued, but is also professional and efficient, will make a positive difference in participant retention. For example, long waiting times associated with study visits and inconvenient appointment scheduling can disinterest study participants, leading to higher dropout rates. Simple steps can be taken to ensure that patients feel their time is valuable enough that they return for future visits and finish the study. Be sure to provide ample parking so the participant is not frustrated prior to even entering the building. Although it can be difficult, also try to keep the scheduled appointments running on time, as the longer participants have to wait, the more likely he or she may become agitated and unhappy. Having a variety of appointment dates and times to appease your study participants’ personal schedules will also make them more inclined to return for study visits. In the event that the participant has to wait prior to an appointment, a comfortable waiting room with magazines or books can help keep him or her entertained. Because we can reimburse study participants for their time and expenses incurred as a result of trial participation, also think carefully about what reimbursement funds might look like. If the trial is in an earlier phase, there may be more frequent study visits to account for safety endpoints, so be mindful of the amount of time a participant will spend completing the study and provide appropriate compensation.

Aron Shapiro is Vice President of Retina at Ora Inc., in Andover, MA.