1,240 healthy subjects for a reference range, locked on time
Global diagnostics leader · healthy-population reference-range collection for a new assay panel · 1,240 subjects across ~20 sub-cohort quotas, database lock 15 Dec 2025
The challenge the client gave us
A global diagnostics leader needed reference ranges for a new panel of assays. That's one of the harder asks in diagnostics: not patients, but healthy people from the general population — over a thousand of them — stratified into the cohorts a normal range is built from. Adults across age and sex bands. Pediatric subjects staged by pubertal development (Tanner staging). And pregnant women across all three trimesters.
The catch: every specimen had to move by cold chain to the lab, and the whole collection had to arrive as one clean, monitored, locked dataset by a fixed date. Healthy volunteers don't walk into a clinic the way patients do — so recruitment was entirely RDI's to drive, subject by subject.
At a glance
| Subjects enrolled | 1,240 |
| Sub-cohort quotas | ~20, each with its own eligibility window |
| Sites | 12 (started at 3, expanded through the year) |
| Collection window | ~11 months |
| IRB | Single RDI-sponsored protocol, one central IRB |
| Database lock | 15 Dec 2025 — on the sponsor's date, not after it |
Timeline
- Dec 2024 Protocol finalized, central IRB
- 17 Jan 2025 First IRB approvals; EDC build
- Feb 2025 First subjects; weekly cold chain begins
- Mar–Sep 2025 Enrollment scales; sites expand 3 → 12
- 20 Oct 2025 1,142 enrolled
- 26 Nov 2025 All sites paused at 1,240
- 15 Dec 2025 Database lock on the sponsor's date
- 19 Dec 2025 Collection closed out
What we did as a CRO
| CRO responsibility | What RDI did on this study |
|---|---|
| Regulatory & study start-up | Ran it as a single RDI-sponsored protocol under one central IRB; first approvals 17 Jan 2025, EDC and kits built in parallel |
| Site selection & feasibility | Started with 3 sites and expanded to 12 as the specialized cohorts demanded reach; collected in-house and through a managed investigator network |
| Recruitment & enrollment | Drove recruitment ourselves — advertising, screening, and consent subject by subject — because healthy volunteers don't present like patients; filled ~20 sub-cohort quotas against tight eligibility windows |
| Kits, samples & lab | Built and tracked hundreds of collection kits; shipped weekly on dry ice / cold chain to the central laboratory |
| Monitoring & data | Cleaned data and completed source verification as we went — SDV completed, queries cleared — so nothing piled up at the end |
| Project management & close-out | Paused all sites at 1,240 on 26 Nov, monitored and locked on the sponsor's 15 Dec date, and closed the collection out by 19 Dec |
What made it hard — the eligibility design
A reference range has to represent the whole physiological spectrum, so the protocol wasn't one eligible population — it was roughly twenty sub-cohort quotas, each with its own window. As of early October the structure looked like this:
| Cohort family | Enrolled (early Oct) | Stratification |
|---|---|---|
| Healthy non-pregnant women | 414 | Menstrual-cycle phase (follicular / luteal), menopausal status, age decade |
| Pregnant women | 278 | 1st, 2nd, and 3rd trimester — each a separate quota |
| Pediatric | 367 | Tanner stage 1–5, with Stage 1 split by age (5–6, 7–9) |
| Adult men 51+ | 42 | Age band |
- Many cohorts can only be collected at a specific moment — a given cycle phase, a given trimester — so a willing, healthy volunteer often didn't fit an open bucket, or fell into a slow one (third trimester, Tanner Stage 5, luteal phase).
- "Healthy" was strictly defined. Any drug abuse was exclusionary — including marijuana, which the sponsor flagged specifically, with a minimum abstinence window — so in the general population a large share of otherwise-eligible volunteers screened out.
- The lock date was fixed, and the specialized cohorts are the slow part, so the dataset had to be cleaned continuously rather than at the end.
How we solved it
- We owned recruitment end to end — advertising, screening, and consent subject by subject — instead of waiting for patients to arrive.
- We expanded the network from 3 to 12 sites as the specialized quotas demanded reach, rather than overloading a small footprint.
- We monitored as we went, finishing source-data verification and query resolution ahead of the lock so December wasn't a scramble.
- We ran the cold chain on a weekly cadence with kits built and tracked in-house, so specimens arrived at the lab intact.
The result
Every site was paused at 1,240 subjects on 26 November; all 1,240 were monitored and the database locked on 15 December — the sponsor's date, not after it. The sponsor has since continued with RDI on additional programs.
Source: RDI biweekly project-update correspondence, December 2024 – December 2025. Sponsor name withheld; enrollment figures, cohort structure, and exclusion criteria taken directly from project correspondence. Operations report, not a clinical-results publication.