Common Data Elements: Standardizing Data Collection

Common Data Elements (CDEs)

Examples of Activities and Groups using CDEs

Here are a few examples of activities and groups using common data elements at NIH. Some CDEs are developed into collections that cross disciplines and domains, such as NIH Toolbox, PhenX Toolkit, PROMIS and Neuro-QoL. Some are domain or disease focused, such as the NINDS Common Data Elements (Neurology), eyeGENE (ophthalmic disease), and the National Heart, Lung and Blood Institute (NHLBI) Cure Sickle Cell Initiative.

While CDEs may be new to some, several collections have been established for years in their communities. One example is the National Cancer Institute (NCI), which has been promoting CDEs for over 20 years.

Let’s take a closer look at two collections: NHLBI Cure Sickle Cell Initiative and PhenX.

NHLBI Cure Sickle Cell Initiative

The NHLBI Cure Sickle Cell Initiative has developed a set of CDEs “to facilitate the collection of data on clinical research studies of genetic therapies for sickle cell disease,” with the goal of making research more efficient, open, and rapid to help identify, treat, and reduce sickle cell disease.

The NHLBI Cure Sickle Cell Initiative Data Standards include a list of domains and subdomains to narrow in on specific topics. Domains include:

  • Participant Characteristics
  • Disease or Treatment Related Events
  • Assessments and Examinations
  • Treatment/Intervention Data
  • Safety Data
  • Outcomes and End Points
  • Additional Proposed Instruments
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These CDEs can also be found in the NIH Common Data Element Repository CDEs > NHLBI > Sickle Cell Disease.


On the NHLBI Cure Sickle Cell Initiative Data Standards webpage, scroll down to "Outcomes and Endpoints" and select "Daytime Sleepiness."

Next to "Epworth Sleepiness Scale (ESS) - Adult Version," click on "CDE Details." Review the CDE Detailed Report.

  1. Which of the following is not a description of a permissible value for daytime sleepiness?

PhenX Toolkit

The PhenX (consensus measures for Phenotype and eXposures) Toolkit is a project from the National Human Genome Research Institute (NHGRI). It includes measurement protocols addressing multiple research domains, including COVID-19, Social Environments, Diabetes, Oral Health, and more.

These protocols are intended to facilitate cross-study analysis and therefore increase the scientific impact of individual studies. Because the protocols are accessible from one toolkit, researchers can quickly find standardized data collection tools and find other investigators who are using the same protocol.

The PhenX Toolkit includes a COVID-19 Variable Compare Tool that is designed to assist investigators who are evaluating or choosing between COVID-related questionnaires or surveys to include in their research or study design. Users can search by keyword, perform a side-by-side comparison of variables, or compare questionnaires.

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Try using the COVID-19 Variable Compare Tool in the PhenX Toolkit. Select the Keyword Search tab and search for smoking.

  1. How many questionnaires are using Variable ID PX9915001037000 (Current Smoking)?

  1. What is the source of this variable?