> For the complete documentation index, see [llms.txt](https://docs.coupler.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coupler.io/sources/category/other/castor-edc.md).

# Castor EDC

Connect Castor EDC to Google Sheets, BigQuery, or AI tools via Coupler.io. Export studies, visits, audit trails, and more.

Castor EDC is a cloud-based electronic data capture platform used in clinical research. It helps research teams design studies, collect patient data through forms and surveys, manage site activity, and maintain full audit trails for regulatory compliance.

Connecting Castor EDC to Coupler.io lets you pull your clinical study data into spreadsheets, data warehouses, or AI tools — without manual exports or custom scripts.

**Why connect Castor EDC to Coupler.io?**

* Automate recurring exports of study data, visit records, and audit trails
* Combine data from multiple entities (e.g., join study forms with field validations) using Coupler.io's Join and Aggregate transformations
* Send data to Google Sheets, Excel, BigQuery, Looker Studio, or AI destinations like ChatGPT, Claude, or Gemini
* Keep stakeholders updated with scheduled refreshes — no manual intervention needed

## Prerequisites

* An active Castor EDC account with API access enabled
* Your Castor EDC **Client ID** and **Client Secret** (used as the API key)
* Knowledge of your account's region (UK, NL, or US) — check your Castor EDC account settings

## Quick start

{% hint style="success" %}
If you're new to Coupler.io, start by creating a data flow with the **Studies** entity to confirm your connection is working, then add more entities as needed.
{% endhint %}

{% stepper %}
{% step %}
**Create a new data flow.** In Coupler.io, click **Add data flow** and search for **Castor EDC** as your source.
{% endstep %}

{% step %}
**Enter your API credentials.** Provide your Castor EDC **Client ID** and **Client Secret**. Then select your **URL region** (uk, nl, or us) — this must match the region where your Castor EDC account is registered.
{% endstep %}

{% step %}
**Set a start date.** Use the date picker to choose the earliest date from which you want to export data. This helps limit the volume of records pulled on the first run.
{% endstep %}

{% step %}
**Select an entity.** Choose the data entity you want to export (e.g., Studies, Study visits, Audit trials). You can add more entities to the same data flow later.
{% endstep %}

{% step %}
**Choose a destination.** Select where you want your data to go — Google Sheets, Excel, BigQuery, Looker Studio, or an AI tool like Claude, ChatGPT, or Gemini.
{% endstep %}

{% step %}
**Run the data flow.** Click **Run** to execute a manual sync and confirm that data is flowing correctly.
{% endstep %}
{% endstepper %}

## Available entities

| Entity                   | Description                                     |
| ------------------------ | ----------------------------------------------- |
| Users                    | Platform users and account information          |
| Studies                  | Clinical studies and research projects          |
| Audit trials             | System changes and user activity logs           |
| Countries                | Countries available in the system               |
| Study surveys            | Surveys associated with studies                 |
| Study survey packages    | Packages containing multiple surveys            |
| Study sites              | Physical locations where studies are conducted  |
| Study fields             | Data fields and form elements within studies    |
| Study field dependencies | Relationships between study fields              |
| Study field validations  | Validation rules applied to study fields        |
| Study forms              | Forms used for data collection                  |
| Study roles              | User roles and permissions within studies       |
| Study fieldoption groups | Groups of options for dropdown/selection fields |
| Study statistics         | Statistical metrics for studies                 |
| Study users              | Users assigned to studies and their permissions |
| Study visits             | Patient visits and appointments within studies  |

## Castor EDC 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

{% tabs %}
{% tab title="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
  {% endtab %}

{% tab title="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
  {% endtab %}

{% tab title="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
  {% endtab %}
  {% endtabs %}

## 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

## Castor EDC common issues

### Connection issues

<details>

<summary>Authentication fails when connecting Castor EDC</summary>

This usually means your Client ID or Client Secret was entered incorrectly. Copy them directly from your Castor EDC account settings to avoid typos. Also confirm that API access is enabled for your account — some Castor EDC plans require you to explicitly activate API access.

</details>

<details>

<summary>Connection succeeds but returns no data</summary>

Check that your **start date** is not set too far in the future. If the start date is ahead of when your records were created, the filter will return an empty result. Try setting an earlier date or clearing the field entirely.

</details>

### Missing data

<details>

<summary>Audit trail data is incomplete or missing older records</summary>

The start date parameter filters audit records by timestamp. If you set a recent start date, older audit entries won't be included. To capture your full audit history, use the date picker to set the start date to the beginning of your study or organization's activity in Castor EDC.

</details>

<details>

<summary>Study visits or forms are missing for some studies</summary>

Castor EDC entities like study visits and forms are scoped to individual studies. If a study is archived, unpublished, or your API credentials don't have access to it, those records won't appear. Verify your user role has read access to all relevant studies in Castor EDC.

</details>

<details>

<summary>Study field dependencies or validations return empty results</summary>

These entities only contain data if your studies have conditional logic or validation rules configured. If you haven't set up dependencies or validations in Castor EDC, these entities will be empty by design.

</details>

### Permission errors

<details>

<summary>API returns a 403 Forbidden error</summary>

Your API credentials may not have sufficient permissions. In Castor EDC, API access is tied to user roles — ensure the account associated with your Client ID has at least read-level access to the studies and entities you're trying to export.

</details>

<details>

<summary>Can only see some studies, not all</summary>

Access to individual studies in Castor EDC is controlled per user. If your account is only assigned to certain studies, the API will only return those. Contact your Castor EDC organization admin to request access to additional studies.

</details>

### Data discrepancies

<details>

<summary>Study statistics don't match what I see in the Castor EDC dashboard</summary>

Statistics in Castor EDC may be calculated in real time from live data, while Coupler.io exports reflect a snapshot at the time of the last sync. Run the data flow again to get an up-to-date export. If numbers still differ, check whether filters (like site or date range) are applied in the Castor EDC dashboard but not in your export.

</details>

### Rate limits

<details>

<summary>Sync fails or times out on large exports</summary>

Castor EDC's API enforces rate limits that can affect large exports, particularly for audit trails on long-running studies. Use the start date parameter to limit the volume of data pulled per run. If you're exporting audit trails for a multi-year study, consider splitting exports by setting different start dates across multiple data flows.

</details>

{% hint style="warning" %}
If you repeatedly hit rate limits, avoid running multiple Castor EDC data flows simultaneously. Stagger them so they don't compete for API quota.
{% endhint %}

## Castor EDC FAQ

<details>

<summary>Can I export data from multiple Castor EDC studies in one data flow?</summary>

Castor EDC's API returns data across all studies your account has access to for most entities. For example, the Studies entity will list every study you can access. For entities like study visits or study forms, records from all accessible studies are included. If you need to separate them by study, you can filter the output in your destination or use Coupler.io's transformation options.

</details>

<details>

<summary>Where do I find my Castor EDC Client ID and Client Secret?</summary>

Log in to your Castor EDC account and go to **Account Settings**. Look for the API or developer section where credentials are managed. If you don't see this option, API access may need to be enabled by your organization admin or may require a plan upgrade.

</details>

<details>

<summary>What does the URL region setting do, and which one should I pick?</summary>

Castor EDC operates separate instances for the UK, Netherlands (NL), and US. Your data lives in only one of these regions — the one you registered with. Pick the region that matches your Castor EDC account URL (e.g., if you log in at uk.castoredc.com, choose "uk"). Using the wrong region will cause authentication to fail.

</details>

<details>

<summary>What is the difference between Audit trials and Study statistics?</summary>

Audit trials (audit trail) are a row-by-row log of every action taken in the system — who changed what, when, and what the value was before and after. Study statistics are aggregated metrics like enrollment counts, completion rates, and open query counts. Use audit trails for compliance and traceability; use study statistics for high-level progress reporting.

</details>

<details>

<summary>Why are study field dependencies and validations empty?</summary>

These entities only contain records if your study design includes conditional field logic (dependencies) or validation rules (validations). If you haven't configured these in Castor EDC, the entities will return no rows. This is expected behavior, not a connection error.

</details>

<details>

<summary>Can I use Castor EDC data with AI tools like ChatGPT or Claude?</summary>

Yes. Coupler.io supports AI destinations including ChatGPT, Claude, Gemini, Cursor, Perplexity, and OpenClaw. You can send your Castor EDC study data — like statistics, visit summaries, or form structures — directly to these tools to generate analysis, summaries, or documentation.

</details>

<details>

<summary>How do I combine data from study visits and study sites?</summary>

Add both **Study visits** and **Study sites** as sources in the same Coupler.io data flow, then use the **Join** transformation to link them on the site ID field. This gives you a single table showing visit activity broken down by location — useful for multi-site trial management.

</details>

<details>

<summary>How current is the data after a sync?</summary>

The data reflects the state of your Castor EDC instance at the moment the data flow runs. There is no real-time streaming — each run captures a snapshot. For time-sensitive use cases like audit trail monitoring, schedule more frequent refreshes.

</details>

{% hint style="info" %}
For a full list of available entities and what data each one contains, see the [Data Overview](#castor-edc-data-overview) article. For help with connection errors or missing records, check [Common Issues](#castor-edc-common-issues).
{% endhint %}


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