Castor EDC/CDMS Tips and tricks - Before starting
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In Castor CDMS, we use specific terms with a certain goal. Using this article, you can learn more about these terms, what they mean, and how you can use them.
Form: the eCRF structure that contains all your study Visits, Repeating Data structures and surveys, where you will create all the fields that are relevant for your study. The form consists of the following elements:
- Visit: a specific study period which contains one or more Forms.
- Form: a sub-section within each Visit that contains multiple fields.
- Field: a question that needs to be answered, such as “How old is the subject?”
Participant: a “case” - this is usually a participant in your study, but can also be a sample or another instance. A version of the form that you build will be available within each participant.
Study vs. Repeating Data structure vs. Survey
While Repeating Data structures and surveys are also part of the study itself, Castor distinguishes these two from the basic study structure.
Study: the main study structure that you will create, based on your study protocol. Here you should add all of the scheduled study Visits in which you will be collecting all the necessary data. For example, a study can consist of the Visits: Inclusion, Baseline, Follow-up. In each of these Visits, you can create additional Forms and fields to represent the data you will be capturing.
Repeating Data structure: part of the eCRF used for unscheduled Visits or events, such as adverse events, concomitant medications and repeated measurements. Characteristics of a Repeating Data structure:
- Repetitive: multiple Repeating Data forms can be filled in on multiple occasions for the same subject (has a N:1 relationship with the participant). This means that several adverse event Repeating Data instances can be registered for the same subject.
- Unscheduled: it is not part of the planned study, but needs to be recorded in the form.
- Same structure as the study: contains the same Form/field structure as the general study form - thus the Repeating Data structure will also contain fields representing questions that need to be answered.
- Can be linked to a certain study Visit or another Repeating Data structure.
Survey: a form used to create a survey that you will send out to participants.
Characteristics of a survey:
- Relies on the same Form/field structure as the main study: separate Forms are the separate sections/pages of a survey and fields are the questions that need to be answered.
- Always belongs to a survey package: surveys are sent in the form of 'packages' and even if you want to send a single survey, it has to be sent in the form of a survey package.
- Contains unique URLs that are sent to the respondents' email addresses and are automatically attached to the participants (study participants) they have been sent to. Additionally, it is also posssible to send a survey via Castor Connect app. The answers of the respondents are automatically captured in the appropriate participant.
- Can be linked to a certain study Visit or Repeating Data structure.
- Possibility to schedule in advance and send repetitively.
Tip: Repeated Measures
In Castor, a Repeated Measure is a type of a Repeating Data structure that can be used for any type of repeated data capture. For example, repeated ECG measurements or a medication diary can be captured using repeated measures. Although considered a Repeating Data structure as per the Castor structure, the repeated measures can also be part of your main study structure.
Characteristics of the repeated measure:
- Scheduled or unscheduled: e.g. repetitive blood pressure measurement that can be a scheduled part of the study protocol or a follow-up to an adverse event
- Repeating Data structure structure: considered to be a Repeating Data structure, as its structure has to be created under 'Repeating Data structures'. Can be reflected in the study structure or another Repeating Data structure in the form of a table
- Relies on the same Form/field structure as other Repeating Data structures: the main difference is that it contains one Form and the fields within the Form appear as columns in a table, where the rows reflect each separate measurement.
Tip: Create a data dictionary
Before you start building your study in Castor we recommend that you make a data dictionary. A data dictionary is a file containing definitions of every field that you want to use. To help build your data dictionary, use the following 3 Forms as a guide:
- Define your field types:
- Define what type of data you will be capturing and choose the appropriate field types and variable names. These can be numerical fields, date or date and time fields, dropdown fields etc.
- Define the lower and upper limits of the fields and think about checking whether the entered value is correct. These checks are called validations.
- Option labels and values: e.g. Male = 1, Female = 2 or Yes = 1, No = 0 (these definitions depend on your preference).
- Think about how you are going to analyse your data and if you are going to use these options as stratification factors or for further calculations/dependencies in your CRF.
- Think about using standards, such as predefined templates.
- Define what values are “normal”
- Define option groups
Here is a part of an example data dictionary:
- Participant: in Castor a participant is one "case". This can be a patient, but also an animal, sample etc.
- Form: a list of fields, e.g. a demographic form containing fields with patient information regarding age, gender or country of origin.
- Field: a question, such as: "What is the patient's age?"
- Visit: a study period which contains forms.
Adding new data fields
When you create fields always make sure that the question you want to ask is noted in the 'Label' field. Where possible, you should always enter the name of the variable in the ‘Variable name’ field. Names of the variable will be used in export files and calculation fields.
When using option groups in your study fields (e.g. radio buttons), we strongly advise that you are sure this is the correct method for your research, as it is difficult to change this later.
Copying of fields/forms
When you want to use the same field format multiple times, you can use the copy function. Fields can easily be reproduced by clicking the copy icon (see image). This enables you to quickly compile a list - for example, multiple yes or no questions. You can adjust the labels of the fields by double clicking the label name in the form builder
You can also copy whole Forms in this way. Before copying a Form, we advise you to thoroughly test the Form to prevent having to amend each copied Form. You can test your form by:
- Creating a test participant and filling in data for several patients.
- Export your data to see if it fits your expectations.
- Invite colleagues to test the form.
For more information on testing your forms, please follow this link.
Did you know that Visits and Forms can be hidden from predetermined users? This ensures that users can only view forms that are relevant to them. You can do this by selecting users that are not allowed to view the Form with the ‘assign user roles’ button (see image below). Before doing this, you do need to assign roles to each user. You can find out how to do this here.
Always check the user rights before starting your data collection. Click here for more information on user rights.
A few common user rights are:
|Data input||Add, view, edit (For the site for whom the data is gathered)|
|Study monitor||View, query (For the site that needs to be monitored)|
|Study admin||Depending on the tasks that need to be executed, this user has all management rights|
|Sending of Surveys||Add, view|
|Randomization||View, randomize, view randomization (if not blinded)|
|Principal investigator||View, edit, sign|
We advise to always use the ‘clear inapplicable child fields’ function in the 'Settings' tab. This function ensures that fields that are hidden because of dependency are cleared.
Besides this, consider what kind of participant IDs you are planning to use. We advise to use incremental IDs for each site or to use a unique pattern that the site uses. For more information on changing participant IDs, follow this link.
In Castor you can use calculations to obtain more information from your data. For example, when you wish to calculate a patient's age or calculate the difference between two dates. You can find common calculation templates here.