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Using CDISC Standards in an EDC Study

According to a recent EDC study, CDISC standards have completely changed the way data is collected in EDC studies, yet the adoption process can still be painstakingly long. By setting up an EDC study using CDISC standards, you will reduce the amount of queries generated, improve data quality and reduce the time to lock your database. Providing a consistent set of CRF questions and responses will also lead to more compliant sites when it comes to entering data, and understanding what is expected of them when collecting their EDC study data.

Below are some common questions with related to setting up EDC studies with CDISC standards. These questions were originally answered in my recent Webinar titled 'Using CDISC Standards in an EDC study.'

    1. Why can’t the data simply be collected in SDTM format eliminating the need for CDASH?
      A large percentage of the data CAN and SHOULD be collected directly in the SDTM format. In these cases, CDASH helps out by providing the detailed question text, question order and collection instructions. There are some cases where the SDTM format is not conducive to data entry, and in those cases, CDASH makes recommendations on how to best collect the data, then how to derive the SDTM variable from that data.
    2. What are EDC study best practices when it comes creating a CDISC compliant CRF?
      • Name all the variables with their SDTM names when applicable.
      • Use CDISC Terminology for code list names.
      • Implement the data cleaning questions using system workflow features. For example, after asking 'Was the ECG performed?' if the answer is YES, then enable entry for the specific ECG results. If the answer is NO, then do not permit the site to enter result data.
      • Derive data that is required in SDTM right in the EDC system.
      • Derive some of the variables needed right in the EDC system. Examples are: VISITNUM, VISIT, VSTPT, USUBJID. These variables are not data entered by the site, but data related to the visit and subject ID.
      • Provide consistency and correctness checks for date and time values.
      • Use pull down lists containing CDISC Terminology when applicable so that sites cannot enter free text when an expected value can be chosen from a list.
    3. What standard in CDISC has the answers to the questions?
      The CDISC Terminology standard provides a finite set of values that represent the only allowed values for a data value. For example, the code list SEX is defined as "The assemblage of physical properties or qualities by which male is distinguished from female; the physical difference between male and female; the distinguishing peculiarity of male or female. (NCI)," and has four acceptable values:


CDISC Synonym CDISC Definition
Female A person who belongs to the sex that normally produces ova. The term is used to indicate biological sex distinctions, or cultural gender role distinctions, or both. (NCI)
Male A person who belongs to the sex that normally produces sperm. The term is used to indicate biological sex distinctions, cultural gender role distinctions, or both. (NCI)
U; Unknown Not known, not observed, not recorded, or refused. (NCI)
Undifferentiated A person (one of unisexual specimens) who is born with genitalia and/or secondary sexual characteristics of indeterminate sex, or which combine features of both sexes. (NCI)


  1. How do I set up a custom CDASH CRF?
    This answer is too detailed to include in this blog post. You really shouldn’t have missed my webinar!
  2. What are vertical vs. horizontal datasets?

    Horizontal datasets are long and wide datasets, for example:
    002-0014 BASELINE 2009-01-02 09:00 183 68 14


    Vertical datasets are short and skinny datasets, for example:













    Pulse Rate





    Respiration Rate




    SDTM datasets are always vertical datasets, but your data collection tool may be better oriented horizontally. In this case, by all means, collect the data horizontally. There are details in the CDASH standard about how to convert your horizontal structures to vertical structures.

Do you have any more questions on setting up an EDC study using CDISC standards? I would be happy to answer them for you. Please feel free to respond to this blog post with your questions and comments.


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