Using Fishbone Diagrams to Uncover Root Causes in Clinical Trial Deviations

Understanding the Fishbone Diagram in Clinical RCA

When a protocol deviation occurs in a clinical trial, identifying the true root cause—not just the immediate symptom—is vital. Regulatory agencies including the FDA, EMA, and MHRA increasingly expect structured Root Cause Analysis (RCA) approaches. One such tool that facilitates this process is the Fishbone Diagram, also known as the Ishikawa Diagram or cause-and-effect diagram.

The Fishbone diagram provides a visual representation of all potential contributing factors to a deviation. It’s especially useful when:

• ✅ The deviation involves multiple people or systems
• ✅ You need input from a cross-functional RCA team
• ✅ The deviation repeats or has complex origins

This structured approach not only helps identify the real problem but also facilitates targeted Corrective and Preventive Actions (CAPA), in line with GCP expectations.

Components of a Fishbone Diagram

The “head” of the diagram represents the problem—typically the deviation. The “bones” are broad categories of potential causes. Common categories adapted for clinical trial RCA include:

• People – Human error, training issues, workload
• Processes – Inefficient workflows, missing SOPs
• Technology – EDC system errors, eTMF access issues
• Environment – Site conditions, distractions, interruptions
• Materials – Incomplete visit checklists, incorrect documents
• Management – Oversight lapses, delegation errors

Each “bone” is then populated with specific causes identified during the investigation.

Step-by-Step Guide: Applying the Fishbone Diagram

Let’s walk through the process of building and analyzing a Fishbone diagram for a real-world deviation scenario.

Case Study: Multiple subjects missed ECG assessments during Visit 3 across 3 sites.

1. Step 1 – Define the Problem: “Missed ECG assessments at Visit 3 for subjects at sites A, B, and C.”
2. Step 2 – Draw the Fishbone Framework: Place the problem statement at the diagram’s head and draw six main “bones” for each category listed above.
3. Step 3 – Brainstorm Possible Causes: Use the RCA team to populate each category with actual contributing factors observed or reported.
4. Step 4 – Analyze Clusters: Look for recurring themes or patterns across categories.
5. Step 5 – Identify the Most Probable Root Cause(s): Validate findings using supporting documentation such as monitoring reports, training logs, or EDC timestamps.

External Resource: For examples of standardized tools for clinical trial investigation, you can explore the Australian New Zealand Clinical Trials Registry for insight into site documentation practices.

Example Fishbone Diagram Breakdown

Here’s a simplified breakdown based on the case study above:

From this structured analysis, the RCA team determined the root causes to be: insufficient training on Visit 3 procedures and poor checklist design. The findings then directly fed into a multi-site CAPA plan.

Benefits of Fishbone Diagrams in Clinical Trials

• ✅ Provides a clear, visual map of possible contributing factors
• ✅ Encourages team-based investigation
• ✅ Reduces reliance on “human error” as a default explanation
• ✅ Creates audit-ready documentation for inspectors
• ✅ Drives data-informed CAPA decisions

Tips for Effective Implementation

• ✅ Use templates during RCA meetings for consistency
• ✅ Train QA and monitoring staff on fishbone facilitation
• ✅ Always validate findings with objective evidence
• ✅ Archive diagrams with the deviation and CAPA logs
• ✅ Periodically review Fishbone trends across studies to spot systemic issues

Pro Tip: During sponsor or CRO audits, present Fishbone diagrams as part of the RCA narrative—it demonstrates a culture of structured problem solving.

Regulatory Expectations and Audit Readiness

Both the FDA’s BIMO program and EMA’s GCP inspection frameworks emphasize robust RCA processes. The Fishbone method helps demonstrate:

• ✅ A systematic approach to deviation investigation
• ✅ Participation of all responsible stakeholders
• ✅ Traceable documentation that supports CAPA development

Inspectors will often ask: “How did you determine this was the root cause?” A well-documented Fishbone diagram provides the answer with visual clarity.

Conclusion: Visualizing Compliance with Fishbone Diagrams

Fishbone diagrams bring structure, objectivity, and teamwork to the complex task of root cause analysis in clinical research. They help move organizations away from generic explanations and toward focused CAPA strategies that enhance trial quality and inspection readiness.

Incorporating this tool into your quality system ensures that deviations are not only addressed—but truly understood. That understanding is what drives prevention, performance, and patient safety.

Essential Root Cause Analysis Tools for Clinical Trial Deviation Investigations

Why Root Cause Analysis Is Critical in Clinical Research

When a protocol deviation or non-compliance occurs in a clinical trial, documenting the event is only the first step. Regulatory authorities and Good Clinical Practice (GCP) guidelines require a thorough investigation into the root cause to prevent recurrence and to ensure data integrity and subject protection.

Root Cause Analysis (RCA) is the structured process of identifying why a deviation occurred, rather than just treating the symptoms. RCA plays a foundational role in the development of Corrective and Preventive Actions (CAPA), audit readiness, and continuous quality improvement.

Agencies such as the FDA and EMA expect sponsors and CROs to use RCA tools that are standardized, reproducible, and fit for purpose. Improper or shallow root cause assessments have led to warning letters, delayed submissions, and even study holds.

Key RCA Tools Used in Clinical Research

Various tools and frameworks are available for conducting structured RCA in GCP environments. Below are the most widely used:

• 5 Whys Analysis
• Fishbone (Ishikawa) Diagram
• Fault Tree Analysis (FTA)
• Failure Mode and Effects Analysis (FMEA)
• Barrier Analysis
• Cause and Effect Matrix

Each tool has its advantages depending on the complexity of the deviation and the availability of site or process data.

Using the 5 Whys for Simple Deviation Investigations

The 5 Whys technique is ideal for simple, single-cause deviations. It involves asking “Why?” iteratively (typically five times) to drill down to the core problem.

Example: A subject was dosed without completing a visit ECG.

1. Why was the ECG missed? → Staff forgot to perform it.
2. Why did staff forget? → The ECG checklist wasn’t followed.
3. Why wasn’t the checklist followed? → Staff was covering for a sick colleague and unfamiliar with the workflow.
4. Why was the substitute untrained? → No backup staff training program existed.
5. Why was there no training program? → SOPs didn’t mandate cross-training.

Root Cause: Lack of SOP for backup staff training.
CAPA: Revise SOP, implement training matrix, and add ECG check to the pre-dose checklist.

Fishbone Diagrams for Complex Root Cause Mapping

Also known as the Ishikawa Diagram, the fishbone tool is useful for visualizing multiple potential root causes across categories. This is especially helpful in complex deviations involving people, processes, technology, and environment.

Common categories include:

• People (training, staffing, roles)
• Process (SOPs, workflows, handoffs)
• Equipment (IT systems, monitoring devices)
• Environment (site workload, time pressure)
• Materials (forms, templates, protocol)
• Management (oversight, communication)

Tip: Use fishbone diagrams during cross-functional deviation review meetings to align sponsor, site, and CRA perspectives.

Cause-and-Effect Matrix for Prioritizing Root Causes

When multiple causes are identified, a Cause-and-Effect Matrix helps prioritize them based on severity, occurrence, and detectability. This is especially valuable in evaluating systemic issues or in large-scale deviations across sites.

Example Matrix Structure:

Higher scores indicate higher priority for CAPA planning. This matrix helps sponsors focus their quality improvement resources effectively.

Documentation Expectations for RCA Tools

Regulators expect RCA results to be documented clearly and stored as part of the CAPA record or Deviation Investigation Report. A complete RCA package should include:

• ✅ Description of the deviation
• ✅ Tool(s) used for RCA (e.g., 5 Whys, Fishbone)
• ✅ Identified root cause(s)
• ✅ Supporting evidence (meeting minutes, audit trail)
• ✅ CAPA developed based on the RCA
• ✅ Effectiveness check plan

Note: Avoid listing “human error” as the sole root cause. Regulatory authorities expect deeper process-based or systemic causes, such as inadequate training or poor workflow design.

Regulatory Insights on RCA Expectations

Authorities such as the FDA, EMA, and MHRA have cited sponsors for:

• ❌ RCA tools not used or documented
• ❌ CAPAs developed without identifying true root causes
• ❌ Repetitive deviations with no formal RCA conducted

During inspections, auditors will often request RCA documentation for major deviations, asking how the root cause was determined and how CAPA was linked to it. Using structured tools increases transparency and regulatory confidence.

Conclusion: Embedding RCA Tools into Clinical Quality Systems

Effective use of RCA tools goes beyond fixing a deviation—it helps sponsors and CROs prevent recurrence, improve trial quality, and pass inspections. Whether using the simple 5 Whys or the more advanced Cause-and-Effect Matrix, RCA should be built into every CAPA process, QA review, and deviation SOP.

Invest in RCA training for site staff, CRAs, and QA professionals, and ensure that your quality management system includes templates, timelines, and escalation pathways for RCA execution. A structured, documented approach to deviation investigations will elevate both compliance and credibility in every clinical trial.