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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

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

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:

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

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3. Set up User Rights, Roles, &/or DAG’s

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  • 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 & Roles

  • 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. 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

4. Define Events (and/or) Arms

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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.

6. Test, Test & Test

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.

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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 Event, 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 offsetand use an accurate representation in case you ever want to use scheduling

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