Data Overview

Castor EDC exposes a broad set of entities covering study structure, participant activity, user management, and compliance tracking. Here's a breakdown of what's available through Coupler.io.

Entities overview

Entity	What it contains
Users	User IDs, names, email addresses, account roles
Studies	Study IDs, names, status, configuration metadata
Audit trials	Timestamps, user actions, field changes, record IDs
Countries	Country codes and names available in the system
Study surveys	Survey IDs, names, associated study, status
Study survey packages	Package IDs, included surveys, assignment details
Study sites	Site IDs, names, countries, status, study association
Study fields	Field IDs, types, labels, form association, options
Study field dependencies	Parent field, dependent field, condition logic
Study field validations	Field ID, validation type, rule parameters
Study forms	Form IDs, names, type, associated study and phase
Study roles	Role IDs, names, permission sets
Study fieldoption groups	Group IDs, option labels, values
Study statistics	Enrollment counts, completion rates, query metrics
Study users	User-study assignments, roles, access levels
Study visits	Visit IDs, names, scheduled dates, patient associations

Metrics and dimensions

Study statistics

Metric	Description
Enrolled participants	Total number of participants enrolled in a study
Completed records	Count of fully completed data records
Open queries	Number of unresolved data queries
Completion rate	Percentage of forms or fields completed

Audit trail dimensions

Dimension	Description
Timestamp	Date and time of the logged action
User	Who performed the action
Action type	Create, update, delete, or view
Record ID	The affected record or field
Old value / New value	Before and after state of changed data

Study visit dimensions

Dimension	Description
Visit name	Label for the scheduled visit
Visit date	Scheduled or actual date of the visit
Site	Site where the visit occurs
Patient ID	Associated participant identifier

Study field dimensions

Dimension	Description
Field type	Text, numeric, date, dropdown, etc.
Field label	Display name of the field
Form association	Which form the field belongs to
Required	Whether the field is mandatory

Common entity combinations

• Study fields + Study field validations — Join these to see every field alongside its validation rules. Useful for auditing data quality standards across a study.
• Study users + Study roles — Join to understand who has what access across your studies.
• Study visits + Study sites — Join to map visit activity by location, helpful for multi-site trial oversight.
• Audit trials + Users — Join to attribute every system change to a named user for compliance reporting.
• Study statistics — Use Aggregate to roll up enrollment and completion metrics across multiple studies.

Use cases by role

Clinical data managers

• Export study fields and field validations to document your data dictionary outside Castor EDC
• Pull audit trails regularly to maintain a compliance-ready log of all data changes
• Use study statistics to track form completion rates and open queries across active studies

Research coordinators

• Monitor study visits to track upcoming and completed patient appointments
• Combine study sites with visit data to compare activity across locations
• Export study surveys and survey packages to report on participant engagement

IT and data engineers

• Load all entities into BigQuery to build a centralized clinical data warehouse
• Use Join transformations to link users, roles, and study assignments in a single table
• Send audit trail data to Looker Studio for real-time compliance dashboards
• Pipe study statistics to ChatGPT or Claude to generate narrative study progress summaries

Platform-specific notes

• Castor EDC has three regional instances (UK, NL, US) — data is isolated per region, so your API credentials and exports only cover the region you registered in
• The start date parameter filters records by creation or modification date; without it, the full history is pulled on first run
• Audit trials can grow very large in long-running studies — setting a meaningful start date is especially important for this entity
• Study field dependencies and validations reflect the study design at the time of export; if you redesign a form, re-export to capture the updated structure
• The study_fieldoption_groups entity is only relevant for studies that use dropdown or multi-select fields