What is it? Why is it important?

Variables are medical values or information of interest to a researcher. When planning and setting-up a study, only variables defined in the study protocol can be collected and used for analysis.

Variables are either:

  • Quantitative based on the process of counting or measuring something (e.g. age, weight, lab values, health scores, percentage)
  • Qualitative which are non-numerical characteristics but can be fitted according to categories (e.g. eye colour, gender, education)

Research variables are often discussed in terms of cause and effect relationships (e.g. cigarette smoking can cause lung cancer).

More

Here some varaible guidelines to follow:

  • Variables should provide all necessary information to a researcher needed to answer the study question
  • Variables entered in the study database (eCRF) should be collected as completely as possible. Incomplete or missing variables should be avoided
  • The visit-plan defining the schedule of study visit during study conduct must be followed. No visits must be removed or added as this would alter the amount of variables being collected
  • Submit the CRF (eCRF and pCRF) with its list of variables to the EC for approval
  • In the event a researcher wants to collect additional data not defined in the study protocol, he/she must initially submit a protocol amendment to the EC for approval. The same would apply to changes to the study visit-plan. Only after EC approval can changes be implemented

What do I need to do?

As a SP-INV:

  • Define variables needed to answer your study question including
    • The source (SD) where the data is retrieved (e.g. laboratory reports, physical examination, medical history, patient file,  participant diary)
    • Means used to collect data (e.g. iPad/tablet, pCRF, questionnaires, physician interviews)
  • Consult a statistician to ensure variables are suitable for statistical analysis, such as:
    • The selection of appropriate and measurable study variables. This is especially important in order to ensure variables are useful in the interpretation of study results (e.g. study endpoint)
    • The implementation of harmonised data formats (e.g. implemented codes, classifications)
  • Document selected variables and their rationale in the study protocol and the DMP

 

For more information refer to Statistics and Protocol in this Trial Guide.

More

During study conduct the collection of variables might depend on study progress, such as:

  • Some study endpoint variables are only collected towards the end of a study (e.g. cancer status 6 months after treatment stop, % blood pressure improvement after 6 weeks treatment compared to baseline)
  • Descriptive variables might only be collected at the beginning of the study, such as during a screening- or baseline visit (e.g. age, gender, disease characteristics at study start, level of education, socioeconomic factors)

The visit-plan provides a good overview to study staff and ensures that no variables are forgotten during study conduct. Thus, the collection of study variables should be well structured:

  • List study visits in chronological order based on study progress (e.g. screening visit, baseline visit, followed by interim- until last study visit)
  • Group those variables together that are repeatedly collected during subsequent visits (e.g. recurrent medical examinations)
  • Group variables according to the time point when they must be collected

Where can I get help?

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

References

ICH GCP E6(R2) – see in particular guideline

  • 5.5. Trial Management, data handling, and record-keeping

Swiss Law

ClinO – see in particular article and annex

  • Art. 5 Rules of Good Clinical Practice
  • Annex 3 Application documents to be submitted to EC
Abbreviations
  • ClinO – Clinical Trials Ordinance
  • CTU – Clinical Trials Unit
  • DMP – Data Management Plan
  • EC – Ethics Committee
  • CRF – Case Report Form
  • eCRF – electronic Case Report Form
  • pCRF – paper Case Report Form
  • ICH GCP – International Council for Harmonisation Good Clinical Practice
  • SD – Source Data
  • SP-INV – Sponsor-Investigator
Development ↦ Data Handling ↦ Database Development ↦ Variables
Study
Basic

Provides some background knowledge and basic definitions

Basic Protocol
Basic Management
  1. Study Management
    1. Definition
Basic Ethics and Laws
  1. Principles of Ethics Research
    1. Declaration of Helsinki
    2. Declaration of Taipei
  2. Authorities
    1. Ethics Committee
    2. Swissmedic
    3. Federal Office of Public Health
    4. International
  3. Swiss Law
    1. Human Research Act
    2. Transplantation Act
    3. Stem Cell Research Act
    4. Data Protection Act
  4. Clinical Trials Ordinance
    1. Aim
    2. Medicinal Products
    3. In Vitro Diagnostic Medical Device
    4. Standardized Transplant Products
    5. Gene Therapy, GMO, Pathogenic
    6. Transplantation
    7. Other Clinical Studies
    8. Ionising Radiation
  5. Human Research Ordinance
    1. Aim
    2. Projects with Data and Biological Material
    3. Further use of Data and Biological Material
    4. Further use and Informed Consent
    5. Deceased Persons Embryos and Foetuses
  6. Medical Device Ordinance
    1. Aim
    2. In Clinical Studies
    3. Notified Bodies
  7. Organisation Ordinance
    1. Aim
  8. Portals
    1. Human Research Portal
    2. Ethics Portal BASEC
    3. Swissmedic Portal
  9. Guidelines
    1. Good Clinical Practice
    2. ISO 14155
    3. ISO 20916
Basic Documents
  1. Document Management
    1. Purpose
    2. In Studies
    3. Document Identification
    4. Document Filing
  2. Standard Operating Procedures
    1. Purpose
  3. Working Instructions
    1. Purpose
  4. Logs
    1. Purpose
  5. Essential Documents
    1. Requirement
  6. Certified Copies
    1. Procedures
  7. Staff Documents
    1. Qualifications
    2. Training
Basic Safety
  1. Safety Laws
    1. Aim
  2. Safety Terminology
    1. Overview
  3. Safety Data
    1. Product Development
    2. Pre-Clinial Studies
    3. In Clinical Studies
  4. Safety Information
    1. Investigator Brochure
  5. Safety Vigilance
    1. Pharmacovigilance
    2. Materiovigilance
Basic Data Handling
  1. Data Management in Studies
    1. Aim
  2. Study Database
    1. Clinical Data Management System
    2. Study Data
    3. Raw Data
    4. Metadata
  3. Regulatory Requirements
    1. Swiss Law
    2. EU Regulation
Basic Statistics
Basic Quality and Risk
  1. Risk Management Definitions
    1. Risk-Based Approach
    2. Risk Identification
    3. Risk Evaluation and Prioritisation
    4. Risk Evaluation Matrix
    5. Risk Control Measures
  2. Quality Management System (QMS)
    1. Risk Based
  3. Risk-Based QMS Responsibilities
    1. Sponsor-Investigator
    2. Site-Investigator
    3. Study Staff
Basic Monitoring
Basic Drug or Device
Basic Biobanking
Concept

Starts with a study idea

Ends after having assessed and evaluated study feasibility

Concept Protocol
Concept Management
  1. Study Idea
    1. Implementation
    2. Design
  2. Resources
    1. Study Staff
    2. Infrastructure
    3. Storage
    4. Partners
    5. Budget
Concept Ethics and Laws
  1. Study Categorisation
    1. Procedures
    2. Risk Categories
  2. Regulatory Advice
    1. Scientific Advice
    2. Pre-Submission
  3. Regulatory Advice Meeting
    1. Ethics Clarification
  4. Research Aim
    1. Advancing Science
    2. Marketing Products
  5. Research Integrity
    1. Principles
    2. Conflict of Interest
    3. Participant Protection
  6. Study Planning
    1. Ethics Requirements
    2. Laws and Guidelines
    3. Institution Requirements
  7. Study Feasibility
    1. Ethics and Laws
Concept Documents
  1. Required Documents
    1. Protocol and Synopsis
    2. Feasibility
    3. Investigator's Brochure
Concept Safety
  1. Safety in Studies
    1. Risk-Benefit Ratio
    2. Participant Risk-Benefit
Concept Data Handling
  1. Stakeholders
    1. Sponsor-Investigator
    2. Data Manager
    3. Statistician
    4. Site-Investigator
    5. Monitor
  2. Clinical Data Mgmt. System
    1. Selection
  3. Server Management
    1. Data Storage
    2. Back-Up and Recovery
Concept Statistics
Concept Quality and Risk
  1. Study Feasibility
    1. Aim
    2. Feasibility Questionnaire
    3. Risk Assessment Form
    4. Study Team
Concept Monitoring
  1. Monitoring
    1. Aim
    2. Study Requirement
    3. Site Feasibility
Concept Drug or Device
Concept Biobanking
Development

Starts with confidence that the study is feasible

Ends after having received ethics and regulatory approval

Development Protocol
Development Management
  1. Responsibilities
    1. Sponsor-Investigator
    2. Site-Investigator
    3. Staff Qualification and Training
    4. Good Clinical Practice Training
  2. Quality Mgmt. System
    1. Implementation
    2. Interim Analysis
  3. Study Management
    1. Oversight
    2. Tracking
    3. Infratructure and Maintenance
    4. Multi-centre Studies
    5. Insurance
    6. Outsourced Services
    7. Contract
    8. Budget
  4. Study Documents
    1. Protocol
    2. Participant Information Sheet
    3. Informed Consent Form
    4. Exemption from written Consent
    5. Informed Consent Process
    6. General Consent
    7. Essential Documents
    8. Source Data
  5. Study Approval
    1. Ethics Committee
    2. Swissmedic
    3. Fed. Off. Public Health
  6. Biobanking
    1. Management
    2. Emergency Plan
Development Ethics and Laws
  1. Ethics Application
    1. Submission
    2. Application Dossier
    3. Approva
  2. Swissmedic Application
    1. Application Dossier
    2. Early Clarification Meeting
    3. Late Clarification Meeting
    4. Approval Medicinal Products
    5. Approval Medical Device
  3. Federal Office of Public Health
    1. Submission
    2. Approval
  4. Liability
    1. Insurance
    2. Good Clinical Practice
Development Documents
  1. Required Documents
    1. Study Protocol
    2. Participant Information
    3. Insurance and Contract
    4. Study Documents
    5. Document Submission
Development Safety
  1. Safety Documentation
    1. The Protocol
    2. Study Documents
    3. Data Protection
Development Data Handling
  1. Database Development
    1. Variables
    2. Variable Specification
    3. Case Report Form
    4. Automated Data Processing
    5. Data Coding and Anonymisation
    6. Data Confidentiality
  2. Data Quality
    1. Requirement
    2. Quality Assurance
    3. Data Mgmt. Plan
  3. Database Lock
    1. Procedures
Development Statistics
Development Quality and Risk
  1. Study Risk Management
    1. Risk Identification
    2. Risk Evaluation and Prioritisation
    3. Risk Control Measures
    4. Process Verification and Training
  2. Quality Assurance
    1. Aim
    2. Quality Documents
    3. Audit
  3. Quality Control
    1. Aim
    2. Monitoring
    3. Non-Compliance
  4. Risk Communication
    1. Strategy
Development Monitoring
  1. Montoring Strategy
    1. Aim
    2. Risk-Based Monitoring
    3. On-Site Monitoring
    4. Central Monitoring
    5. Monitoring Plan
Development Drug or Device
Development Biobanking
Set-Up

Starts with ethics and regulatory approval

Ends after successful study initiation

Set-Up Protocol
Set-Up Management
  1. Registration
    1. Research Transparency
  2. Study Training
    1. Staff
  3. Document Management
    1. Requirements
  4. Investigational Product
    1. In Studies
  5. Laboratory
    1. Aim
  6. Study Ready for Conduct
    1. Requirements
  7. Study Monitoring
    1. Site Initiation Visit
Set-Up Ethics and Laws
  1. Study Set-Up
    1. Requirements
Set-Up Documents
  1. Required Documents
    1. Study Initiation
    2. Master and Site File
Set-Up Safety
  1. Safety Management
    1. Safety Management Plan
    2. Emergency Unblinding
  2. Data Safety Monitoring Board
    1. Aim
Set-Up Data Handling
  1. Database Set-Up
    1. Requirement
    2. Access Rights
    3. Training
Set-Up Statistics
Set-Up Quality and Risk
Set-Up Monitoring
  1. Site Initation Visit
    1. Aim
    2. Prerequisite
    3. Preparation
    4. Conduct
    5. Report
Set-Up Drug or Device
Set-Up Biobanking
Conduct

Starts with participant recruitment

Ends after the last participant has completed the last study visit

Conduct Protocol
Conduct Management
  1. Participant Recruitment
    1. Pre-Screening
    2. Screening and Consent
    3. Documentation of Recruitment
  2. Amendment
    1. Protocol
    2. Patient Information Sheet
  3. Safety
    1. Reporting
    2. Annual Safety Reporting
    3. Interim Analysis
  4. Responsibility and Oversight
    1. Site-Investigator
    2. Routine Monitoring
    3. Risk Review
    4. Drug Accountability
    5. Compliance
    6. Newsletter
    7. Essential Documents
    8. Budget
Conduct Ethics and Laws
  1. Study Conduct
    1. Ongoing Tasks
    2. Data Protection
  2. Participant Protection
    1. Requirements
    2. Consent of Vulnerable Participants
  3. Amendment
    1. Type
    2. Submission
    3. Approval
  4. Safety
    1. Requirements
  5. Inspections and Audits
    1. Inspection Conduct
    2. Audit Conduct
    3. Audit Certificate
  6. Premature Study Termination
    1. Rationale
    2. ReportingTimelines
Conduct Documents
  1. Required Documents
    1. Study Documentation
    2. Patient File
    3. Source Data
    4. Amendment
Conduct Safety
  1. Safety Risk Review
    1. Aim
  2. Safety Assessment
    1. Medicinal Product
    2. Medical Device
    3. Other Clinical Trials
    4. Research Projects
  3. Safety Reporting
    1. Procedures
    2. Responsibilities
  4. Medicinal Product Safety Reporting
    1. Adverse Event
    2. Serious Adverse Event
    3. (Serious) Adverse Drug Reaction
    4. Suspected Unexpected Serious Adverse Reaction
    5. Advanced Therapies
  5. Medical Device Safety Reporting
    1. Adverse Event / Adverse Device Effect
    2. Serious Adverse Event and Device Effect
    3. Device Deficiency
  6. Research Project Safety Reporting
    1. Serious Events
  7. Safety and Protective Measures
    1. Procedures
  8. Annual Safety Report
    1. Procedures
Conduct Data Handling
  1. Data Entry
    1. Requirement
    2. Collection
  2. Data Quality
    1. Responsibility
    2. Adding New Sites
  3. Data Handling
    1. Data Import
    2. Interim Lock
    3. Intermediate Data Eport
    4. Amendment
Conduct Statistics
Conduct Quality and Risk
  1. Risk Review
    1. Re-Evaluation
    2. Risk Documentation
  2. Deviation Documentation
    1. Note to File
  3. Regulatory Inspections
    1. Conduct
    2. Findings
    3. Corrective and Preventive Actions
Conduct Monitoring
  1. Routine Monitoring Visit
    1. Preparation
    2. Conduct
    3. Findings
    4. Report
    5. Follow-Up Letter
Conduct Drug or Device
Conduct Biobanking
Completion

Starts with last study visit completed

Ends after study publication and archiving

Completion Protocol
Completion Management
  1. Study Closure
    1. Close-Out Visit
    2. Database Lock
    3. Notification of Closure
    4. Lessons Learned
  2. Clinical Study Report
    1. Regulatory Requirements
  3. Publishing
    1. Study Registries
    2. Scientific Publications
  4. Archiving
    1. Storage
Completion Ethics and Laws
  1. End of Study Notification
    1. ReportingTimelines
    2. Liability Coverage
    3. Registry Update
  2. Clinical Study Report
    1. Procedures
  3. Publications
    1. Responsibilities
  4. Inspections and Audits
    1. Procedures
  5. Archiving
    1. Requirements
    2. Duration
Completion Documents
  1. Required Documents
    1. Study Closure
    2. Doument Archiving
    3. Document Destruction
Completion Safety
  1. Clinical Study Report
    1. Procedures
Completion Data Handling
  1. Final Database Lock
    1. Procedures
  2. Data Export
    1. Data Formatting and Tranfer
    2. Data Transfer Agreement
  3. Clinical Study Report
    1. Requirement
  4. Archiving
    1. Requirement
Completion Statistics
Completion Quality and Risk
  1. Clinical Study Report
    1. Risk Reporting
    2. Lessons Learned
  2. Archiving
    1. Study Records
Completion Monitoring
  1. Close-Out Visit
    1. Preparation
    2. Conduct
    3. Report
    4. Follow-Up Letter
    5. Archiving
Completion Drug or Device
Completion Biobanking
Current Path (click to copy): Development ↦ Data Handling ↦ Database Development ↦ Variables

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