Why do willing, eligible patients disappear before they enroll in a clinical trial?

When a patient drops off before enrolling, it is easy to assume they were never serious. Often, that is not what happened. This Health Literacy Month, it is worth naming the quieter reason interested patients walk away: they could not tell whether the clinical trial was relevant to them, what participation would involve, or whether taking the next step was worth it.

Barriers to clinical trial enrollment can begin long before a patient reaches a clinical site. When study information is difficult to understand, willing and eligible patients may struggle to determine whether they qualify, what participation involves, or how to move forward.

Nearly 9 in 10 US adults don’t have proficient health literacy (National Assessment of Adult Literacy, US Department of Education). In Antidote's survey of almost 4,000 patients, the ones who understood clinical research were twice as likely to say they would take part. Interest was not the dividing line. Understanding was.

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The drop-off you cannot see on a dashboard

A protocol is written for researchers and regulators. When that same language reaches a patient as an advertisement, a landing page, or a pre-screening questionnaire, an interested patient can hit friction before they ever reach a clinical site. They may decide the clinical trial is not for them and leave. The clinical site may never know why.

That is what makes this loss so easy to miss. It happens before any funnel report can catch it. A campaign can look healthy on impressions and clicks while the patients who could not read it quietly fall away.

These are some of the barriers to clinical trial enrollment that recruitment teams may overlook. A patient may click an advertisement and still fail to understand the study requirements. Another may begin a pre-screening questionnaire but leave because the questions are confusing. Others may not know what happens after they express interest.

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Not every patient who drops off has lost interest. Some never understood clearly enough to take the next step.

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Interest was never the barrier

Patients are not staying away because they do not care. In our survey, they told us the opposite. They want the industry to make clinical trials easier to understand, and they trust a real person or a fellow patient far more than an advertisement. Give them plain language from a source they trust, and willing patients move forward. Bury the opportunity in clinical terminology, and they disappear.

And the first click is only one place where comprehension can break down. The same friction can appear during pre-screening, follow-up, and the eventual clinical site handoff.

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Common barriers to clinical trial enrollment

Barriers to clinical trial enrollment can occur at different stages of the patient journey. Even when patients are interested in participating, unclear information and difficult processes can prevent them from taking the next step.

Common barriers include:

• Complex medical terminology: Patients may struggle to understand clinical trial descriptions, eligibility criteria, or study procedures.
• Unclear participation requirements: Patients may not know what taking part involves, how much time it requires, or what happens next.
• Confusing pre-screening questionnaires: Complicated questions can make it difficult for patients to determine whether they may qualify.
• Communication gaps: Unclear next steps or delayed follow-up can leave interested patients unsure how to proceed.
• Trust and information gaps: Patients may need clear explanations and access to a trusted person who can answer their questions.

Understanding these barriers helps research teams identify where patients may disengage before reaching a clinical site.

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How research teams can reduce enrollment barriers

Improving patient understanding does not necessarily require more recruitment activity. It may start with making each step easier to understand and complete.

Research teams should also consider practical obstacles that affect participation. Learn more about ways to reduce patient burden in clinical trials.

Research teams can consider the following approaches:

• Use plain language: Explain the study purpose, eligibility requirements, and participation expectations in language patients can understand.
• Make the next step clear: Tell patients what will happen after they click an advertisement, submit a form, or complete pre-screening.
• Simplify patient-facing materials: Review advertisements, landing pages, and questionnaires for unnecessary jargon and confusing wording.
• Provide timely follow-up: Help patients understand their options and know whom to contact when they have questions.
• Make human support accessible: Give interested patients a way to speak with a knowledgeable person who can explain the process.

These approaches can help research teams reduce avoidable friction. They do not guarantee enrollment, since patients may also face personal, medical, or logistical barriers.

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Frequently asked questions

What are the main barriers to clinical trial enrollment?

Common barriers include complex medical language, unclear eligibility criteria, confusing pre-screening processes, communication gaps, and practical challenges that make participation difficult.

What is health literacy?

Health literacy is the ability to find, understand, and use health information to make informed decisions. In clinical trials, it helps patients understand study requirements, potential risks and benefits, and what participation involves.

How does health literacy affect clinical trial enrollment?

When patient-facing materials are difficult to understand, patients may struggle to assess their eligibility or decide whether to participate. Clear, accessible information can help them make informed decisions.

Why do eligible patients drop off before enrolling?

Patients may leave because study information is confusing, eligibility criteria are unclear, or the next steps are not explained. Some potentially eligible patients disengage before a clinical site can assess them.

How can research teams reduce barriers to clinical trial enrollment?

Research teams can simplify study materials, clarify eligibility requirements, explain next steps, and provide timely follow-up to make enrollment easier to navigate.

When is Health Literacy Month?

Health Literacy Month takes place every October. It raises awareness of the importance of making health information easier to understand and use.