Published on 21/12/2025

Recording Onset and Resolution Times of Adverse Events in eCRFs

Introduction: Importance of Onset and Resolution Recording

The accurate recording of time of onset and time of resolution of adverse events (AEs) is critical for safety data integrity in clinical trials. Regulators such as the FDA, EMA, and MHRA require sponsors to capture AE chronology in electronic case report forms (eCRFs) to determine relationships to study drugs, assess seriousness, and meet expedited reporting timelines. Recording only the event description without timing data risks obscuring safety patterns and undermining causality assessments.

Onset and resolution data not only inform causality determination but also contribute to trial-level analyses such as median AE duration, correlation with dosing cycles, and impact on treatment discontinuations. This tutorial explores how onset and resolution recording should be structured in eCRFs, regulatory expectations, real-world challenges, and best practices for ensuring accurate, complete, and inspection-ready AE documentation.

Core Fields for Onset and Resolution in eCRFs

Every AE captured in an eCRF should include both onset and resolution fields. The recommended structure is shown below:

This structured approach ensures that every AE has a documented timeline. Where exact times are unavailable, systems should allow partial dates (e.g., YYYY-MM-DD) with clear documentation. Regulators emphasize that “ongoing” AEs must be updated at subsequent visits until resolution or end of study.

Case Study: Oncology Infusion Reaction

In a Phase II oncology trial, a patient developed chills and shortness of breath during drug infusion at 10:45 AM. The AE was recorded as “Infusion reaction,” but no onset time was captured. During an EMA inspection, auditors identified the missing onset time as a significant finding, as it was critical for differentiating between infusion-related reactions and disease progression. After system updates, onset and resolution fields were made mandatory, improving accuracy and regulatory compliance.

Regulatory Expectations on Onset and Resolution

Authorities have clear expectations regarding AE chronology:

• FDA: Requires onset and resolution times for all SAEs to support causality and expedited reporting (IND safety reports).
• EMA: Expects onset and resolution in EudraVigilance submissions, with “ongoing” clearly marked if unresolved.
• ICH E2A: Defines onset and resolution as essential data elements in clinical safety data management.
• MHRA: Auditors frequently cite incomplete onset/resolution recording as a critical finding.

Global registries such as the Clinical Trials Registry – India also highlight the importance of standardized AE recording, reinforcing its role in transparency and pharmacovigilance.

Challenges in Capturing Onset and Resolution

Common challenges encountered in trials include:

• Incomplete data: Investigators may capture only start dates without times.
• Ongoing events: Failure to update unresolved AEs at follow-up visits.
• Recall bias: Patients may inaccurately recall the exact timing of symptoms.
• System limitations: eCRFs that do not allow partial dates or mark ongoing events.

Mitigating these challenges requires system flexibility, site training, and continuous monitoring by data managers. For instance, allowing partial date entry with justification reduces delays, while reminders for ongoing AE updates ensure completeness.

Best Practices for Designing Onset/Resolution Fields

To ensure accuracy, sponsors should incorporate best practices such as:

• Make onset and resolution fields mandatory for all AEs.
• Allow partial dates but require justification when time is unknown.
• Use edit checks to prevent illogical entries (e.g., resolution before onset).
• Flag ongoing AEs for follow-up at subsequent visits.
• Train investigators on recording exact times for procedure-related AEs.

For example, in a vaccine trial, system validations prevented entry of “Ongoing” without outcome documentation, reducing data gaps and inspection findings.

Role of Data Managers in AE Timeline Oversight

Data managers ensure consistency and completeness of onset and resolution data by:

• Reviewing missing or illogical AE timelines during data cleaning.
• Generating queries for unresolved AEs without updates.
• Reconciling eCRF data with safety databases to ensure accuracy.

In one global cardiovascular trial, data managers identified inconsistencies where resolution dates were after patient death dates. Queries led to corrections, ensuring inspection readiness and database integrity.

Key Takeaways

Onset and resolution recording is a cornerstone of accurate AE documentation. Sponsors and CROs must:

• Include structured onset and resolution fields in every eCRF.
• Support partial dates with justification and updates for ongoing events.
• Apply validation rules and edit checks to prevent errors.
• Train investigators on importance of precise timing for causality assessment.
• Ensure reconciliation across CRFs, narratives, and safety databases.

By implementing these measures, clinical teams strengthen regulatory compliance, enhance pharmacovigilance quality, and improve patient safety outcomes across trials.