Audit Trail Review: practical step-by-step guide for QC and Manufacturing

Audit Trail Review: step-by-step operational method

Introduction

Audit Trail Review requires method, expertise and a solid understanding of GxP systems.
This guide provides a structured workflow for reviewing audit trails from HPLC/GC, LIMS, MES, SCADA and batch systems, turning the process into an efficient, audit-ready routine.

🔧 Step-by-step guide

1. Identify the relevant audit trails

Classify the system’s audit trails into:

  • critical data
  • non-critical data
  • configuration / user management

According to the guide, this classification must already be defined during URS and system validation.

2. Filter the critical events to be reviewed

For QC (HPLC/GC):

  • chromatogram reprocessing
  • manual integrations
  • data exclusions
  • modifications to methods or sequences

For LIMS:

  • changes to results
  • status changes (review, approval)
  • deleted tests

For Manufacturing:

  • changes to CPP parameters
  • alarms and operator responses
  • steps repeated or cancelled
  • manual overrides in SCADA/PLC

3. Analyse anomalies

Assess whether the event is:

  • covered by procedure
  • justified and documented
  • consistent with timestamps, roles and electronic signature
  • requiring deviation, OOS, investigation or change control

4. Document the review

  • electronic comments (e.g. “Audit Trail Reviewed”)
  • electronic signature on the dataset
  • summary report filtered on relevant events

⚠️ Watch out for…

  • inconsistent timestamps → possible system clock manipulation
  • “Admin” user modifying data → critical violation of Attributable
  • repeated reprocessing → potential attempt to force results
  • missing signatures → failure to follow process steps

❌ Common mistakes and operational solutions

Mistake: printing thousands of unfiltered log lines
Solution: filter only “significant changes”, as recommended in CDS guidance.

Mistake: considering ATR an IT activity
Solution: QC and Manufacturing must perform the review; QA validates and oversees.

Mistake: missing justification for changes
Solution: make the “Reason for Change” field mandatory.

📦 Short checklist

  • critical audit trails identified
  • filters applied for significant events
  • reprocessing / changes / deletions verified
  • consistency of roles and electronic signatures checked
  • alarms and operator actions correctly assessed
  • review properly recorded

Realistic scenario

During an HPLC analysis, the audit trail shows five consecutive reprocessings of the same chromatogram.
The review checks:

  • missing justifications
  • minimal differences between versions
  • no deviation opened

→ The review identifies a potential attempt to alter the results. QA opens an investigation.

Conclusion

An effective Audit Trail Review requires method, smart filtering and critical interpretation. Explore the full guide on GuideGxP.com.

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