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Explanation of Key Terms | Index of All Terms

Explanation of Key Terms

Basic Terminology
The following key terms serve to define the Common Data Element (CDE) Project:

  • Data Element
    • - A logical unit of data, pertaining to information of one kind. A data element has a name, precise definition, and clear enumerated values (codes) if applicable. A data element is not necessarily the smallest unit of data; it can be a unique combination of one or more smaller units. A data element occupies the space provided by field(s) on a paper/electronic case report form (CRF) or field(s) in a database record.

    An example of a data element is race, where a study participant is asked to choose which racial category or categories he/she identifies. The race data element generally consists of the following categories, which are the permissible values/responses: American Indian or Alaska Native, Asian, Black or African-American, Native Hawaiian or Other Pacific Islander, and White.

  • Common Data Element (CDE)
    • – A data element that can be used in multiple clinical studies, as determined by a working group of experienced clinical researchers assembled by the NINDS. The CDEs are content standards that can be applied to various data collection models and are intended to be dynamic standards that may evolve over time. The goal of the NINDS CDE Project is to develop standard definitions, code lists, and instructions for the CDEs so that investigators collect them consistently across studies. CDEs are the foundation for interoperability among data systems and are a subset of the universe of all data elements.
    • General CDE
      • – A data element that can be consistently collected across all clinical studies, regardless of disease or therapeutic area. Examples include the CDEs collected on the following forms: Demographics, Physical Exam, and Adverse Events.
    • Disease-specific CDE
      • – A data element specific to a particular disease or therapeutic area. The NINDS is developing disease-specific CDEs for a variety of diseases including, but not limited to: epilepsy, stroke, Parkinson’s disease, traumatic brain injury, and spinal cord injury.

Classification Terminology
The universe of all data elements (not just CDEs) for a particular disease or disorder can be classified using the terms defined and depicted below:

  • Core CDEs
    • – Data elements collected by most, if not all, clinical studies. The NINDS and their appointed working groups assign the “Core” classification based on the current clinical research best practices. This term applies to the General CDEs and Disease-specific CDEs, and in both cases is a small subset of the General/Disease-specific CDEs. It is anticipated investigators will collect the Core CDEs.

    Examples of the General Core CDEs include the basic demographic information and medical history data collected from all study participants. Examples of Disease-specific Core CDEs are the Stroke CDEs that describe stroke type and those that comprise the NIH Stroke Scale.

  • Conditional CDEs
    • – Data elements that are commonly collected in clinical research studies but their relevance depends upon the study design (i.e., clinical trial, cohort study, etc.) or type of research involved. With one exception*, all CDEs that are not classified as Core are classified as Conditional.

    Examples of Conditional CDEs are the Epilepsy CDEs related to electroencephalogram (EEG) that are only relevant to epilepsy studies that use EEG for diagnostic purposes and the Stroke CDEs related to administration of Tissue Plasminogen Activator (tPA)that are relevant to acute ischemic stroke studies but not relevant to intracerebral hemorrhage (ICH) studies.

* There is one additional, though rare, term that is used to classify the CDEs:
  • Emerging CDEs
    • – Data elements that require further validation but may fill current gaps in the CDEs and/or substitute for existing CDEs once validation is complete. These data elements show great promise but are not quite ready for prime-time use in clinical research studies yet.

    Examples of Emerging CDEs are those included in the instrument batteries being developed as part of the NIH Toolbox and those included in the item banks of the Patient-Reported Outcomes Measurement Information System (PROMIS).

  • Protocol-specific data elements
    • –The remaining data elements collected by a study that are important to the protocol but are NOT considered CDEs. In fact, the NINDS recognizes that the most important variables collected by a study may not be CDEs.

    Examples of Protocol-specific data elements are those pertaining to how a specific intervention being studied is administered or data elements that comprise a new disease-specific quality of life assessment that is being developed.

Index of All Terms


Page last updated on Thursday, April 29, 2010