Glossary
The enrollment terms sites and vendors argue about
Written from the site side. Most vendor disputes are definitional: two parties using the same word for different points in the funnel.
- Patient recruitment vs patient enrollment
- Recruitment is everything that gets a candidate to raise a hand. Enrollment is a signed consent and a randomization. Vendors are usually paid for the first and judged on the second, which is the root of most disputes.
- Screen failure rate
- The share of consented candidates who do not go on to randomize because they fail eligibility. It is measured after consent, not before — a common source of inflated vendor funnel numbers.
- Clinical trial screen fail rate benchmark
- There is no single benchmark. Broad cardiometabolic studies often sit in the 20–40% range while criteria-heavy oncology studies can exceed 60%. Any vendor quoting one universal number is quoting a sales figure. Use your own historical data from comparable protocols.
- Pre-screening
- Assessment before informed consent, typically a questionnaire or a phone call, to remove obviously ineligible candidates. It is limited by what can be asked without consent, so pre-screened does not mean eligible.
- Referral to randomization ratio
- How many referrals it takes to produce one randomized patient. The single most useful number for judging a recruitment vendor, and the one least often volunteered. Ask for it by indication and by country.
- Randomization rate
- Randomizations per site per month. It is the metric enrollment forecasts are built from and the one that reveals a struggling study earliest.
- Site activation timeline
- The elapsed time from site selection to the site being able to consent its first patient: contracting, budget negotiation, ethics approval, training, and supply. It routinely takes longer than the recruitment plan assumes.
- Site initiation visit (SIV)
- The formal visit where the sponsor or CRO trains site staff on the protocol and confirms readiness. A site cannot enroll before it happens, so SIV scheduling is an enrollment constraint, not an administrative one.
- Site management organization (SMO)
- An organization that operates or supports a group of research sites, handling staffing, contracting, and sometimes patient identification. Distinct from a CRO, which serves the sponsor.
- What a patient recruitment company does
- Generates and qualifies candidates, and increasingly supports sites in converting them: outreach, pre-screening, referral routing, scheduling support, and retention. Some also identify sites. Very few own the randomization outcome.
- CRO vs patient recruitment company
- A CRO runs the trial: monitoring, data, regulatory, site management. A recruitment company supplies patients into it. They can be the same vendor, which is convenient until enrollment slips and there is nobody independent to hold accountable.