The Right Recruitment Mix: What Each Channel Is Actually Good For

Sites often ask "which recruitment channel is best?" The honest answer: they do different jobs, and the mix matters more than any single channel.

The channel profiles

Your database and registry. Cheapest per enrollment by a wide margin, fastest to activate, and finite. Always the first pull, never the whole plan.

Physician referrals. High conversion — the patient arrives pre-qualified and pre-trusted — but slow and volume-limited. Referral relationships are built over quarters, not weeks, and they decay without feedback. Sending referring physicians updates on their patients (with consent) is the single best way to keep the pipeline warm.

Paid social media. Nearly unlimited volume and precise demographic targeting, but the lowest lead quality of any channel. Expect high unqualified rates and budget for the pre-screening effort accordingly. Where it shines: common conditions, broad criteria, and geographies where you have no existing presence.

Community outreach and events. Modest immediate yield, high long-term value — especially for building trust in populations that research has historically underserved. Treat it as registry-building, not study-filling.

ClinicalTrials.gov and registries/aggregators. Free or cheap, self-motivated patients, but unpredictable volume and often geographically scattered.

Matching mix to study

A rare-disease protocol should be weighted toward physician networks and patient advocacy groups; paid social will mostly burn money. A seasonal allergy study can lean heavily on ads and volume pre-screening. A long-term outcomes study needs the trust profile of referrals and community presence.

Measure to the enrollment, not the lead

The channel with the cheapest leads is rarely the one with the cheapest enrollments. Track cost per enrolled participant by source — it routinely reorders the priority list, and it's the only number a sponsor actually cares about.