Glossary
First patient in (FPI)
The milestone when the first participant enrolls in a study or at a site. Sponsors watch the time from site activation to first patient in closely.
What does First patient in (FPI) mean in clinical research?
First patient in (FPI), also called first subject in, marks the first participant enrolled in a clinical trial; the CDISC Glossary defines it as the first subject enrolled.[1] Sponsors track FPI for the study as a whole and for each site, where the telling measure is the time from site activation to first enrollment. Check the protocol for what counts as enrolled, since some studies count signed consent and others count randomization.
The gap between activation and first enrollment is often long. In the CREST-2 trial, the median time from authorization to randomize to the first randomization at a site was 4.6 months.[2] A 2024 DIA Global Forum article co-authored by Tufts CSDD researchers cites Tufts CSDD data that only 60% of activated sites in a trial enroll a patient.[3]
Practical note: start finding candidates before activation. Counting likely patients during feasibility and getting outreach materials into the IRB submission means the site can contact candidates and book screening visits as soon as it is activated. Identify builds that ranked candidate list from the EHR.
Sources
- 1.NCI Thesaurus C142559: First Subject In Identity (CDISC Glossary) · National Cancer Institute EVS / CDISC, 2026Quote: "The first subject enrolled. See also enrollment."
- 2.Factors Associated With Time to Site Activation, Randomization, and Enrollment Performance in a Stroke Prevention Trial · Stroke (American Heart Association), via PubMed, 2017Quote: "The median time between authorization to randomize and a randomization was 4.6 months (interquartile range, 2.6, 10.5)."
- 3.Documenting the "Last Mile" Leak in the Patient Recruitment Pipeline · DIA Global Forum, 2024Quote: "Only 60% of activated investigative sites in any trial enroll a patient" (attributed in the article to Tufts CSDD).