> ## Documentation Index
> Fetch the complete documentation index at: https://docs.carelane.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Study Arms

> Define treatment arms and cohorts for your study

Study arms represent the different treatment groups or cohorts in your clinical research study. Configure arms to organize participants and enable arm-specific data collection.

## What are Study Arms?

Arms define distinct groups within a study, such as:

* Treatment vs. placebo groups
* Different dosing regimens
* Multiple intervention types
* Observational cohorts

## Arm Types

Carelane supports standard clinical trial arm types:

| Type                   | Code                 | Description                                 |
| ---------------------- | -------------------- | ------------------------------------------- |
| **Experimental**       | `experimental`       | Receives the experimental intervention      |
| **Active Comparator**  | `active-comparator`  | Receives an active treatment for comparison |
| **Placebo Comparator** | `placebo-comparator` | Receives a placebo                          |
| **Sham Comparator**    | `sham-comparator`    | Receives a sham procedure                   |
| **No Intervention**    | `no-intervention`    | Receives no intervention                    |
| **Other**              | `other-arm-type`     | Custom arm type                             |

## Creating Arms

<Steps>
  <Step title="Navigate to Arms">
    Open Study Design > Arms.
  </Step>

  <Step title="Add New Arm">
    Click "Add Arm" to create a new arm.
  </Step>

  <Step title="Configure Arm">
    Enter arm details:

    * Name (e.g., "Treatment A")
    * Type (select from available types)
    * Description of the intervention
  </Step>

  <Step title="Save">
    Save the arm configuration.
  </Step>
</Steps>

## Arm Configuration

Each arm can be configured with:

| Field           | Description                              |
| --------------- | ---------------------------------------- |
| **Name**        | Display name for the arm                 |
| **Type**        | Classification from standard arm types   |
| **Description** | Detailed description of the intervention |

## Assigning Participants to Arms

Participants are assigned to arms during or after enrollment:

### During Enrollment

When adding a participant, select their arm assignment if known at enrollment time.

### After Enrollment

Update a participant's arm assignment:

1. Open the participant record
2. Navigate to study information
3. Update the arm assignment
4. Record the reason for assignment or change

<Note>
  Arm assignments are recorded with timestamps and can be changed if the study design allows for crossover or reassignment.
</Note>

## Arm-Specific Pathways

Pathways can be configured to differ by arm:

* Different visit schedules per arm
* Arm-specific questionnaires
* Conditional activities based on arm assignment

<Accordion title="Configuring Arm-Specific Activities">
  When designing a pathway, you can set activities to only appear for specific arms. This enables:

  * Intervention-specific assessments
  * Different follow-up schedules
  * Arm-conditional CRFs
</Accordion>

## Reporting by Arm

Data exports and reports can be filtered and grouped by arm:

* Export participants by arm
* Generate arm-specific summaries
* Compare outcomes across arms

## Best Practices

<AccordionGroup>
  <Accordion title="Use Standard Types">
    Use the predefined arm types when possible for consistency and regulatory clarity.
  </Accordion>

  <Accordion title="Clear Naming">
    Use descriptive names that clearly identify the arm without ambiguity.
  </Accordion>

  <Accordion title="Document Assignment Criteria">
    Clearly document how participants are assigned to arms (randomization, investigator choice, etc.).
  </Accordion>
</AccordionGroup>

## Related

<CardGroup cols={2}>
  <Card title="Objectives" icon="bullseye" href="/study-design/objectives">
    Define study objectives and endpoints.
  </Card>

  <Card title="Participant Pathways" icon="route" href="/participants/participant-pathways">
    Configure arm-specific pathways.
  </Card>
</CardGroup>