REDCap - Repeatable Instruments

REDCap has the ability to repeat a data collection instrument or an entire event of instruments an unlimited number of times without having to specify the amount needed. This is sometimes called one-to-many data collection, in which a project can have one or more repeating parts. For example, if each record in a hypothetical project represents a person, then one might have a repeating instrument for medications, one for family members, one or adverse events, and one for collecting data over multiple visits (or weekly surveys), so that each repeating element is connected to the overall record but can repeat independently of the other instruments. So if using repeating instruments or repeating events, each record in the project can have a different number of repeated instances of any given instrument or event. One record may have five medications, but another may have two or none, for example. Such flexibility makes this feature very powerful, and setting up repeating instruments and/or repeating events in a project is very quick and easy. The repeating instruments/events feature can be enabled and set up by clicking the Enable button in the Optional Modules section on the Project Setup page.

Repeating Instruments (for classic and longitudinal projects)

Classic projects (i.e., in which the longitudinal module is not enabled) can utilize repeating instruments as a very simple way of doing longitudinal data collection. When traditionally using the longitudinal module in a project, one downside is that one must specify all the events (i.e., the repetitions of instruments) ahead of time, making sure to build out the maximum number of events that one might need, even though all of them likely won't be used by all records. However, with the repeating instruments functionality, one does not need to specify how many repetitions will needed ahead of time; one can simply repeat an instrument an unlimited amount of times. It is important to note that multiple instruments in a project can be enabled as repeating instruments (even all of them, if one wishes). Projects utilizing the longitudinal module can have repeating instruments as well, in which one or more instruments on any defined event can be set to repeat within that event. The repeating instruments functionality behaves very much the same way in both classic and longitudinal projects.

Repeating Events (for longitudinal projects only)

If a project has the longitudinal module enabled, it can utilize the repeating events feature, which works somewhat differently than the repeating instruments feature. While the repeating instruments feature allows one to repeat a given instrument as a single unit, the repeating events feature allows one to repeat an entire event of instruments together in unison. This might be useful if one has several instruments whose data correlates together, such as completing multiple surveys back to back for a specific time-point or visit, for example. Previously, one may have had to create X number of identical events to capture repeating data for the instruments on those events (e.g., Week 1, Week 2, ...), but the repeating events feature makes this much simpler by allowing one to create only one single event that can be repeated in unlimited fashion.

Enabling Surveys for Repeating Instruments

If one wishes to allow survey respondents to enter their responses in a repeating fashion in survey mode alone, you can enable the 'Repeat the Survey' optional setting near the bottom of the Survey Settings page (in the survey termination options section) *after* an instrument has been set as a repeating instrument. So it is one additional step to do after enabling the instrument itself as a repeating instrument. When the repeat survey setting is enabled, a button will be displayed at the end of the survey so that the respondent can choose to enter another response for the survey, thus allowing them to take the survey multiple times in a row. In this way, they will be able to enter as many responses for that same survey as they need, such as filling out questions about multiple family members or entering medication information for multiple meds. Alternatively, Automated Survey Invitations (ASIs) and Alerts & Notifications may be set up to sent repeatedly on a recurring interval as a way to get respondents to take a repeating survey. For more information on repeating surveys, see Data Collection Strategies for Repeating Surveys.

Reports and Data Exports with Repeating Instruments and Events

If one creates a report that contains data from a repeating instrument or repeating event, a field named 'redcap_repeat_instance' will be included that represents the instance number, which is an auto-numbered value (starting with '1') that gets incremented each time the instrument/event is repeated. And if the report contains data specifically from a repeating instrument (as opposed to a repeating event), then a field named 'redcap_repeat_instrument' will additionally be included that represents the instrument name that denotes to which instrument the row of data belongs. These two fields will only be included automatically in the report or data export if data originates from a repeating instrument or event. Note: Each repeated instance of an instrument or event will be displayed as a new row in the report or export file. This means that if a medications survey is repeated three times for one record, for example, it will be displayed as three rows in the report.