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 include:

  • 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:
    • Incorrect data is entered
    • Data is 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?

As a SP-INV, go through the list of selected study variables and for each variable define applicable technical requirements:

  • Group variables in the Case Report Form (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 visit, study vist 2 and 4)
  • Select appropriate metadata standards for coding your data (e.g. CDISC, 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)


For the database set-up:

  • Define and document all technical requirements including its rational in collaboration with the data manager
  • Upon database set-up include a test-phase(s) to ensure planned specifications and its navigation are implemented as intended
  • Upon the successful completion of the test-phase, sign-off the study database to be released into the productive phase (e.g. input of real-life data)


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

Where can I get help?

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

External Links

CDISC – Provides standards in the clinical research process

CTCAE – Common Terminology Criteria for Adverse Events


ICH GCP E6(R2) – see in particular guideline

  • 5.5 Trial Management, data handling, and record-keeping
  • CDISC – Clinical Data Interchange Standard Consortium
  • CRF – Case Report Form
  • CTCA - Common Terminology Criteria for Adverse Events
  • CTU – Clinical Trials Unit
  • eCRF – electronic Case Report Form
  • ICH GCP – International Council for Harmonisation - Good Clinical Practice
  • SP-INV – Sponsor-Investigator
Development ↦ Data Handling ↦ Database Development ↦ Variable Specification

Provides some background knowledge and basic definitions

Basic Monitoring
Basic Drug or Device

Starts with a study idea

Ends after having assessed and evaluated study feasibility

Concept Drug or Device

Starts with confidence that the study is feasible

Ends after having received ethics and regulatory approval

Development Drug or Device

Starts with ethics and regulatory approval

Ends after successful study initiation

Set-Up Ethics and Laws
Set-Up Quality and Risk
Set-Up Drug or Device

Starts with participant recruitment

Ends after the last participant has completed the last study visit

Conduct Drug or Device

Starts with last study visit completed

Ends after study publication and archiving

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

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