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Longitudinal Projects
This Knowledge Article reviews both Single and Multi-Arm Longitudinal Projects.
It is extremely important to give much consideration to the design, development and testing of your Longitudinal Project. Understanding reporting considerations & needs is critical. Thorough testing is essential for success.
Initial Considerations
Longitudinal projects provide collection of data over time in order to track changes and progress. Longitudinal projects are useful in the following situations:

  • Long Term Studies

  • Clinical Trials

  • Recruitment & Enrollment Combinations

  • Multi-Site Studies

  • Repeating Surveys

Enabling longitudinal feature allows any form or survey to be reused over the course of time and provides opportunity to designate specific instruments at specific time points (events). Longitudinal instruments eliminate the need to recreate the same form for multiple time points. Instead, the form is created once and then assigned to various time points throughout the project. Examples of forms used in longitudinal mode include:

  • Medications

  • Lab results

  • Adverse events forms

The Process These are the basic steps involved in setting up a Longitudinal Project. A step by step process is described in-depth below.

  1. Create Forms

  2. Enable Longitudinal Functionality

  3. Set up User Rights

  4. Define Events / Arms

  5. Link Forms and Events

  6. Test, Test & Test

  7. Setup Schedules (Optional)

Simple Single Arm Longitudinal Study

  1. Create your instruments. See Build a Project

  2. Enable Longitudinal Mode at the project level

    1. Navigate to your project

    2. Select the "Project Setup" tab

    3. Click the "Enable" button next to 'Use Longitudinal data collection with defined events"

  3. Set up User Rights

    1. Assigning User Rights to team members should be a carefully thought out decision. The consequences of poor user rights decisions could be damaging to the security and integrity of the project. See Knowledge Article User Rights

    2. The User Rights page can be used to determine the roles that a user can assume within a REDCap database. The Data Access Group on the other hand determines the data visibility of a user within a REDCap database.

      1. Data Access Groups restrict viewing of data within a database. A typical use of Data Access Groups is a multi-site study where users at each site should only be able to view data from their site but not any other sites. Users at each site are assigned to a group, and will only be able to see records created by users within their group. See Knowledge Article Data Access Groups

    3. Navigate to the left navigation bar and select User Rights:

    4. Add user with customer rights or assign to a role

    5. To create DAG, navigate to tab adjacent to User Rights

  4. Define Events / Arms for the Project (e.g., patient visits, tasks or point in time)

    1. On Project Setup Page, navigate to "Define My Events"

    2. Type the title of the event in the text box then click Add New Event

    3. Repeat above steps until each of your events have been created

  5. Link Instruments to relevant events

    1. From the Project Setup page, navigate to "Designate Instruments for My Events"

    2. Select "Begin Editing" button

    3. Click to place a checkbox on the grid for each instrument / form / survey that should be assigned to each specific event

    4. Click "Save"

    5. In order to ensure that other advanced features like reporting and data quality checks in REDCap work properly, always assign the first form to the first event. (i.e. Order your instruments appropriately)

    6. You can link and un-link events in your project during your project set-up and test. Once the project is in Production linking /unlinking events must be done by REDCap Administrator . Reason: You can lose data if you unlink an event. REDCap provides no warning

  6. Longitudinal Calendar (optional feature. You can not link to Google / Outlook Calendars of the department so rarely used) . However, it does allow a REDCap user to view the calendar, and open any patients scheduled for that day and open the instruments for that event.

    1. Can turn on / off as desired (prod or development)

    2. Can't limit user rights. Have access to calendar and all its features

    3. Produces automatically generated schedules

      • by participant

      • based on how set up Arms and Events

    4. Calendar event status can flag "no show" or "cancel" for visit status

    5. To enable, on Project Setup page navigate to Enable Optional Modules section and click on Enable next to Scheduling module

    6. Click on Scheduling on left navigation bar.

    7. Select a patient (or create new), define start date & ARM, click Generate Schedule

      Can input times and switch scheduled days of the week by changing dates if desired 

    8. When done modifying the Projected Schedule, click Create Schedule

    9. You will see a notice that your calendar was successfully created

      j. To see the Calendar, navigate to left Navigation pane and select Calendar under Applications

k. Here you see the time and event for Participant 3

l. From the calendar, you can click on the event and see:

a. Data entry forms for the participant

b. Study ID, event , status

c. Can add notes as desired

8. Testing

a. It is strongly recommended that you test your projects prior to moving to Production to ensure the project works as desired and reports are presented in the desired format with complete data.

b. Use test data as close to real as possible and simulate the workflow you intend to use.

c. Knowledge Article – Testing Your Project

Advanced Longitudinal Study

  1. Sample Structure of Multiple Arm study.

    1. Two Arms and 3 Events are shown here, but you can have as many Arms & Events as you want / need for your study

    2. Each Arm is its own silo where a record goes

    3. Records should only be in one Arm.

    4. NO record transfer between arms

    5. Can assign forms to various Events and Arms as needed

    6. Arm names can be created & assigned by user. Arm numbers assigned by REDCap

    7. No direct user restriction. If you give user access to a form which is in multiple arms they will be able to see multiple arms

    8. To separate by sites, need to use Data Access Groups or create separate projects

  2. Set up project as described above.

  3. Additional Arms are added on the Define Events Page

  4. Events

    1. Defined by

      1. Event Name (e.g., Baseline, Event 1)

        • Can be assigned by user

      2. Unique Event Name Assigned by REDcap

      1. Assigned by REDCap based on event name and arm #

      2. Based off event name and arm number (Baseline_Arm_1)

        • Important in branching logic and auto invitations

    2. Note the Event Name (User defined) & the Unique Event Name (generated by REDCap) for Arm

    3. Note the Event Name (User defined) & the Unique Event Name (generated by REDCap) for Arm 2

    4. Repeating Events

      1. Only works for Longitudinal Model

      2. Repeat any event as many times as needs

      3. Used for situation where the # of needed events differs per record (e.g. Chemotherapy cycles)

      4. Limitations

        • Makes analysis more challenging

        • Can not add a repeating instrument to a repeating event

  5. Assign instruments to each event. Do this for each Arm as described above

  6. Data Entry

    1. Navigate to Add/Edit Records on Left Navigation Bar

    2. Select Arm Record is to be assign to and create new record or select from dropdown

    3. Select Target Form in the desired Event

    4. Enter Data or open/send survey.

  7. Longitudinal Exports

    1. Multiple Rows for Participants

      1. Exports a row for each Event in each Arm

      2. Lots of blank spaces

    2. Best to use a Statistical Export over Excel to eliminate blank spaces

  8. When Upload, ensure 1 row per record per event

Additional Considerations

  1. Best practice to always add Record ID to every arm to prevent REDCap issues, especially if using surveys

    1. Create a "single landing page" with just Record ID. Can be invisible to user with a "Thanks for Participating Page" with Submit to continue. See Knowledge Article Longitudinal Surveys

  2. Actions that can cause data loss in Longitudinal Projects:

    1. Deleting Events

    2. Deleting Arms

    3. Decoupling Forms from Events

  3. If you create additional forms once project is in Production, need to request REDCap support to link forms to Events.

  4. Give much consideration to User Rights. If you want to segregate data based on location but have a form that is common to both sites, a user with rights to that form will see data from both sites. Create Data Access Groups

  5. Branching logic in a Longitudinal Project must identify the arm and the field name.

    1. Classical Branching Equation:

      1. [field1] = '3'

      2. Longitudinal Branching Equation:

        1. Can cross both forms and events, so need to indicate event and field

        2. [event_3][field1] = '3'

  6. Survey Expiration

    1. Is server time, not what is on your computer

      1. Survey expiration takes all copies of the survey offline.

      2. Warning: If you have survey that is used multiple times in a longitudinal survey if you expire the survey after the first event, be aware that it will expire all the surveys in following events

  7. Save and return later

    1. The User Code is often lost and user can't find the code when they want to return to complete the survey.

      1. Alternative is to design shorter surveys and poll multiple times via automatic invites

  8. Deleting or Disabling a survey in Survey Settings.

    1. There are 2 "delete" buttons for any given project.

      1. 1 is in Online Designer – deletes entire form and data is lost

      2. 1 is in Survey Settings – reverts survey back to a form. Data is still available

  9. When defining Events it is important to think about the days offset and use an accurate representation in case you ever want to use scheduling



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