What is patient recruitment in clinical trials?

Patient recruitment is the process of finding, screening and enrolling people into clinical trials. It sounds simple, but it is consistently ranked as the number one cause of trial delays worldwide. Around 80 percent of clinical trials fail to meet their original enrolment timelines, and many are forced to extend, add sites or close early because too few suitable participants were found.

Recruitment starts long before a patient signs a consent form. Study teams need to raise awareness of the trial, reach the right people through channels such as digital advertising, doctor referrals, patient databases and community outreach, then confirm that interested people actually meet the study's eligibility criteria. Each step loses a large share of candidates: many people who respond to an advertisement will not qualify, and many who qualify will not follow through to a screening visit.

The reasons recruitment fails are well documented. Eligibility criteria have become stricter over time, which shrinks the pool of suitable patients. Awareness is low, with most patients never hearing about trials relevant to them. Follow-up is often slow, so interested patients lose momentum before anyone contacts them. And responsibility is fragmented across sponsors, CROs, vendors and sites, which makes it hard to see where candidates are dropping out of the funnel.

The cost of these failures is significant. Enrolment delays can cost sponsors millions of dollars per day for a pivotal study, and they delay patient access to potential new treatments. For research sites, poor quality referrals waste coordinator hours on people who were never going to qualify.

Modern recruitment addresses these problems with a more accountable model: multi-channel acquisition to reach patients where they are, pre-screening against the protocol before anyone reaches a site, verification of diagnosis and treatment history where required, and real-time reporting so everyone can see how the funnel is performing.

This is the approach Clinrol Recruit takes for sponsors and CROs: patients are found across paid, organic, HCP and community channels, screened by AI and trained staff, and referred to sites as verified, site-ready candidates rather than raw leads. If enrolment is the bottleneck in your study, it is worth understanding this model before committing budget to another lead-volume campaign.