Understanding EPOCH Assignment in Clinical Trials: The Pre-Consent Data Challenge

-

In the world of clinical trials, data management and standardization play crucial roles in ensuring the quality and integrity of research outcomes. One particularly nuanced aspect of this process is the proper assignment of EPOCH values in SDTM (Study Data Tabulation Model) datasets, especially when dealing with pre-consent data.

What is an EPOCH?

An EPOCH in clinical trials represents a distinct period within the study's planned design. It helps organize and contextualize various events, interventions, and findings that occur during the study. Common EPOCHs include SCREENING, TREATMENT, FOLLOW-UP, and others as defined by the study protocol.

Essential EPOCH Characteristics:

  • It is a standardized way to identify different phases of a study
  • Each EPOCH represents a planned element of the study design
  • EPOCHs help establish temporal relationships between different study events
  • They are crucial for data analysis and interpretation of study results

According to SDTM Implementation Guide 3.3 (Section 4.1.3.1), EPOCH is fundamentally a study-design construct. This means it only applies to events that occur after a subject has formally entered the study through the informed consent process.

The Pre-Consent Data Challenge

Clinical researchers often encounter situations where they need to include data that was collected before a subject provided informed consent. This might include:

  • Historical medical records
  • Previous laboratory results
  • Prior medications
  • Earlier adverse events

Why Can't We Assign SCREENING EPOCH to Pre-Consent Data?

It might seem intuitive to assign pre-consent data to the SCREENING EPOCH, as it's typically the earliest study phase. However, this would be incorrect for several important reasons:

Key Points:

  1. The screening period is a protocol-defined phase that occurs only after informed consent
  2. Screening activities are specifically planned and conducted according to the study protocol
  3. Pre-consent data collection wasn't performed under the study's procedures and requirements

The Correct Approach: Using Null EPOCH Values

For any data collected before informed consent, the EPOCH variable should be set to null. This approach:

  • Accurately represents the timing of events relative to study participation
  • Maintains data integrity and transparency
  • Complies with SDTM standards and guidelines
  • Facilitates proper analysis and interpretation of study data

Impact on Data Analysis

Understanding the relationship between EPOCH assignment and informed consent dates is crucial for:

  • Accurate timeline construction
  • Proper assessment of inclusion/exclusion criteria
  • Correct baseline determinations
  • Valid safety and efficacy analyses

Best Practices for Implementation

When implementing EPOCH assignments in your clinical trial data:

  1. Always document the informed consent date accurately
  2. Establish clear procedures for handling pre-consent data
  3. Include proper date variables to establish the timing of events
  4. Implement quality control checks to ensure correct EPOCH assignments
  5. Document your decisions and rationale in the Study Data Reviewer's Guide

Special Considerations for EPOCH Assignment:

  • Protocol Amendments: Consider how protocol amendments might affect EPOCH definitions and assignments
  • Re-screening: Handle cases where subjects may need to be re-screened with appropriate EPOCH assignments
  • Multiple Informed Consents: Account for situations where subjects might sign multiple consent forms for different study aspects
  • Data Integration: Ensure consistent EPOCH assignment across all study domains

Regulatory Compliance and Documentation

Proper EPOCH assignment is crucial for regulatory compliance. When preparing submissions:

  • Ensure your approach is clearly documented in the Study Data Reviewer's Guide (SDRG)
  • Include explanations for any special handling of EPOCH assignments
  • Document any deviations from standard EPOCH assignment practices
  • Maintain traceability between source data and SDTM datasets

Common Challenges and Solutions

Challenge 1: Historical Data Collection
Solution: Clearly identify pre-study data and consistently apply null EPOCH values

Challenge 2: Protocol Amendments
Solution: Document how EPOCH assignments are handled when study design changes

Challenge 3: Multiple Sub-studies
Solution: Develop clear rules for EPOCH assignment across different study components

Challenge 4: Data Integration
Solution: Establish consistent EPOCH assignment rules across all study domains

Conclusion

Proper EPOCH assignment is more than just a technical requirement—it's fundamental to maintaining the scientific integrity of clinical trial data. By correctly handling pre-consent data with null EPOCH values, we ensure our SDTM datasets accurately reflect the study design and subject participation timeline.

Remember: The integrity of clinical trial data depends on accurate representation of when events occurred relative to study participation. Using null EPOCH values for pre-consent data is not just compliant with standards—it's essential for proper data interpretation and analysis.

Last updated: January 2025

Popular posts from this blog

SAS Interview Questions and Answers: CDISC, SDTM and ADAM etc

-
1) What do you know about CDISC and its standards? CDISC stands for Clinical Data Interchange Standards Consortium and it is developed keeping in mind to bring great deal of efficiency in the entire drug development process. CDISC brings efficiency to the entire drug development process by improving the data quality and speed-up the whole drug development process and to do that CDISC developed a series of standards, which include Operation data Model (ODM), Study data Tabulation Model (SDTM) and the Analysis Data Model ADaM ). 2) Why people these days are more talking about CDSIC and what advantages it brings to the Pharmaceutical Industry? A) Generally speaking, Only about 30% of programming time is used to generate statistical results with SAS®, and the rest of programming time is used to familiarize data structure, check data accuracy, and tabulate/list raw data and statistical results into certain formats. This non-statistical programming time will be significantly reduced...
Read more

Comparing Two Methods for Removing Formats and Informats in SAS: DATA Step vs. PROC DATASETS

-
Comparing Two Approaches to Removing Formats and Informats in SAS Comparing Two Approaches to Removing Formats and Informats in SAS When working with SAS datasets, there are times when you need to remove formats and informats that have been previously assigned to variables. Two primary approaches can be used for this task: Using the DATA Step Using the PROC DATASETS Procedure This article compares and contrasts these two approaches to help you determine which method is most appropriate for your needs. Approach 1: Using the DATA Step The DATA step is a versatile and commonly used method for removing formats and informats. By assigning variables to a null format or informat, you can effectively remove these attributes from your dataset. Example: data mydata_clean; set mydata; format _all_; informat _all_; run; In this example, the mydata dataset is processed in the DATA step, and...
Read more

Studyday calculation ( --DY Variable in SDTM)

-
USE OF THE “STUDY DAY” VARIABLES The permissible Study Day variables (--DY, --STDY, and --ENDY) describe the relative day of the observation starting with the reference date as Day 1. They are determined by comparing the date portion of the respective date/time variables (--DTC, --STDTC, and --ENDTC) to the date portion of the Subject Reference Start Date (RFSTDTC from the Demographics domain). The Subject Reference Start Date (RFSTDTC) is designated as Study Day 1. The Study Day value is incremented by 1 for each date following RFSTDTC. Dates prior to RFSTDTC are decremented by 1, with the date preceding RFSTDTC designated as Study Day -1 (there is no Study Day 0). This algorithm for determining Study Day is consistent with how people typically describe sequential days relative to a fixed reference point, but creates problems if used for mathematical calculations because it does not allow for a Day 0. As such, Study Day is not suited for use in subsequent numerical computations...
Read more