What is it? Why is it important?

In order to reduce potential input errors in the study database (eCRF), variables can be specified with additional technical constraints or edit checks.

Input constraints:

  • Range: Limit potential input based on an upper and lower limiting value
  • Format: Only allows input based on a pre-defined or standardised coding list, date format, lab value format (e.g. haemoglobin as g/l or g/dl)
  • Length: Limits input to a maximum of characters or number digits

Navigation options can reduce input errors:

  • Selection: Multiple choice, drop-down menus, radio buttons facilitate and guide staff during data entry
  • Support: Pop-ups with information provided based on the selected input field
  • Mandatory fields: A warning or error message is displayed in the event that:
  1. Incorrect data is entered
  2. Data is still missing and must be entered prior to exiting the database. In the event data will remain missing a code should be defined for this purpose

What do I need to do?

Go through the list of selected study variables and for each variable define applicable technical requirements:

  • Group variables in the CRF according to topic (e.g. lab data)
  • Define who enters variables (e.g. study nurse, participant) and when it must be entered (e.g. baseline-, follow-up visit)
  • Select appropriate metadata standards for coding your data (e.g. CTCAE)
  • For qualitative data, select appropriate categories (e.g. gender, male=1; female=2)
  • Define selective conditions (e.g. show or hide variables under certain conditions)


A user-friendly and fit for purpose database (eCRF) will ensure that collected study data will be of high quality.

Recommendations to follow:

  • Define all technical requirements of the database in collaboration with the data manager of your study
  • Document all technical requirements for the database including its rational
  • Upon database set-up include a test phase(s) to ensure planned specifications and the navigation of the database are implemented as intended

Where can I get help?

Your local CTU can support you with experienced staff regarding this topic

External Links

CTCAE – Common Terminology Criteria for Adverse Events


ICH GCP E6(R2) – see in particular guideline

  • 5.5 Trial Management, data handling, and record-keeping
  • CRF – Case Report Form
  • CTCA - Common Terminology Criteria for Adverse Events
  • CTU – Clinical Trials Unit
  • eCRF – electronic Case Report Form
Development ↦ Data Handling ↦ Study Database ↦ Variable Specification

Provides some background knowledge and basic definitions

Basic Protocol
Basic Statistics
Basic Monitoring
Basic Drug or Device
Basic Biobanking

Starts with a study idea

Ends after having assessed and evaluated study feasibility

Concept Protocol
Concept Statistics
Concept Drug or Device
Concept Biobanking

Starts with confidence that the study is feasible

Ends after having received ethics and regulatory approval

Development Protocol
Development Statistics
Development Drug or Device
Development Biobanking

Starts with ethics and regulatory approval

Ends after successful study initiation

Set-Up Protocol
Set-Up Ethics and Laws
Set-Up Statistics
Set-Up Drug or Device
Set-Up Biobanking

Starts with participant recruitment

Ends after the last participant has completed the last study visit

Conduct Protocol
Conduct Statistics
Conduct Drug or Device
Conduct Biobanking

Starts with last study visit completed

Ends after study publication and archiving

Completion Protocol
Completion Statistics
Completion Drug or Device
Completion Biobanking
Current Path (click to copy): Development ↦ Data Handling ↦ Study Database ↦ Variable Specification

Please note: the Easy-GCS tool is currently under construction.