What Each Recruitment Channel Really Costs You Per Enrollment

Most sites can tell you what they spent on recruitment last quarter. Far fewer can tell you what each channel actually cost per randomized participant. That gap matters, because the channel that looks cheapest at the top of the funnel is often the most expensive by the time someone signs consent.

Start by defining the denominator

Cost per lead, cost per pre-screen pass, cost per consent, and cost per enrollment are four different numbers. Track all four, but make decisions on the last one. Paid social commonly produces the cheapest leads and some of the most expensive enrollments. Physician referrals and your own database usually look expensive per contact and cheap per enrollment, because the qualification work happened before you touched them.

Pick one denominator for budget conversations — enrollments, meaning participants who were randomized or met the sponsor's definition of enrolled — and stick with it across every channel.

Count staff time, not just ad spend

The biggest error in site-level cost analysis is treating coordinator hours as free because they are already on payroll. They are not free; they are the scarcest resource you have.

A workable approach:

1. Assign a fully loaded hourly rate to each role that touches recruitment (coordinator, recruiter, PI time for referral calls).
2. For a two-week sample, log minutes spent per channel — call attempts, pre-screen conversations, chart review, referral follow-up.
3. Multiply and add to the direct spend for that channel.

You do not need perfect timekeeping forever. A periodic sample, repeated once or twice a year, is usually enough to catch the channels quietly consuming half a coordinator's week.

Build the channel ledger

For each channel, capture:

• Direct spend — ad budget, vendor fees, printing, event costs, patient travel reimbursement if channel-specific.
• Labor cost — from your sampling exercise.
• Leads received, pre-screen pass rate, consent rate, enrollment count.
• Time to first contact and lead-to-enrollment lag.

That last pair is underrated. A channel with a 60-day lag can look terrible mid-study and excellent at closeout. If you judge channels on a 30-day window, you will cut the slow ones that were about to deliver.

Interpret with sample size in mind

At site scale, most channels produce single-digit enrollments per study. Three enrollments from a referral partner does not prove a cost per enrollment of $400 is repeatable. Two practices help:

• Pool across studies. Look at a channel's performance across every trial you have run in the last 18 to 24 months, segmented by therapeutic area.
• Watch the funnel ratios, not just the final number. Pre-screen pass rate is a more stable early signal than enrollment count, and it moves first when a channel degrades.

Use the numbers to change behavior

Cost per enrollment is only useful if it changes something. Concretely:

• Shift budget toward channels whose cost per enrollment holds up across studies, not just the one that won last month.
• Renegotiate recruitment line items in budgets using your own historical figures rather than sponsor assumptions.
• Kill the activities that consume coordinator hours and produce nothing — community events and untargeted mailers are frequent offenders.
• Reinvest in database and referral infrastructure, which tends to show the best long-run cost per enrollment in most site datasets.

The goal is not a perfect number. It is a defensible ranking you can act on before the next study starts.