Ask any site leader whether coordinators should enter the same vitals, labs, and clinician ratings twice — once in eSource and again in the EDC — and the answer is always no. Yet duplicate entry persists across therapeutic areas, sponsor stacks, and geographies.
That is because the problem is rarely “coordinators need more training.— It is a systems problem: two record systems, unclear ownership of the source-of-truth field, and no structured path between them.
The three root causes we see most often
1. eSource and EDC were never mapped at the field level
Sponsors deliver CRF specs and edit checks for the EDC. Sites configure eSource (or paper) separately. Without a field-level map — which eSource item populates which EDC field, with what transformation — coordinators become the integration layer.
2. “Source— still lives in more than one place
EMR printouts, lab PDFs, ePRO portals, and handwritten worksheets often hold data that never lands in eSource contemporaneously. Coordinators re-key into the EDC because that is where queries and SDV focus.
3. Automation was attempted too late or too broadly
Sites that try to automate every form on go-live day usually stall. The teams that succeed start with high-volume, structured domains — demographics, vitals, con meds — and expand after monitors sign off on the first wave.
What to fix first (in order)
- Inventory duplicate domains — List visit types and forms where the same data is captured twice today. Rank by volume and query rate.
- Assign a single source-of-truth per field — For each EDC field, document where the authorized source value originates and who attests it.
- Pilot structured automation on one visit window — Use protocol-aligned validation, not copy-paste. Measure time per visit and query counts before expanding.
- Keep coordinators in eSource at the visit — Automation should remove the second step, not add a third system to learn mid-enrollment.
How Nexa Trials approaches it
Nexa Bus connects existing eSource platforms to leading EDCs with field-level mapping and validation — so sites keep their capture workflow and lose the re-entry step. For sites still on paper or scaling fast, NexaSource™ provides a coordinator-first eSource layer that pairs with the same automation path.
See real outcomes in our Toronto Clinical Research Group case study, where structured automation cut duplicate entry by 92% in a Phase 3 program.