External Quality Assessment in Laboratory Testing

External Quality Assessment (EQA)

• An external quality monitoring scheme that consists of "blinded" samples that closely simulate clinical material
• A technique to challenge a laboratory's internal QC methods and procedures
• A program to assess laboratory performance and the ability to determine the "correct" result
• Also termed Proficiency Testing (PT)

Importance of EQA

• Important for improvement
• A measure of laboratory performance

Principles of EQA Schemes

• Challenge participants' quality systems
• Encourage inter-laboratory comparability
• Encourage improvement
• Provide insight into national/international levels of performance
• Allow poor performance to be addressed
• Excellent source of reference material
• Required in licensing (accreditation)

Quality Improvement

• Provides early warning for systematic problems associated with kits or operations
• Provides objective evidence of testing quality
• Indicates areas that need improvement
• Identifies training needs
• Helps to ensure physicians, patients, and health authorities that the laboratory can produce reliable results

Characteristics of a Good EQA Scheme

• Internationally recognized
• Has many participating laboratories
• Numerous and varied samples
• Several distributions throughout the year
• Rapid report turnaround
• Preferably electronic result entry and report return
• Friendly and helpful – advice in trouble-shooting
• Educational

EQA Process

• Management Process
  • Choose the right Scheme for your needs
  • Analyze EQA samples in good time
  • Treat EQA samples same as patient samples
  • Monitor and maintain records
  • Investigate deficiencies
  • Manage corrective action efforts
  • Communicate outcomes

Benefits of EQA

• The Laboratory
  • System confidence
  • Self-assessment and recognition
  • Public confidence
• The Patient
  • Knows the system is working together to ensure the public receives accurate and useful information

EQA Sample Processing

• Receive and process EQA samples
• Analyze data and submit to QA Coordinator
• Enter data in respective accounts provided by the EQA body
• Keep leftover samples until the final report is received

EQA Performance Problems

• Pre-examination
  • Sample may have been compromised during preparation, shipping, or after receipt in the laboratory
  • Sample may have been processed or labeled improperly in the laboratory
• Examination
  • EQA challenge materials may exhibit a matrix effect in the examination system used by the participating laboratory
  • Analytical problems should be investigated to determine whether error is random or systemic
• Post-examination
  • Report format can be confusing
  • Interpretation of results can be incorrect
  • Clerical or transcription errors can be sources of error

Interpretation of EQA Results

• Mean: The mean for a group of data points is simply the calculated average
• Coefficient of Variation (CV): The ratio of the standard deviation to the mean
• Bias: Measures how far your observed value is from a target value
• Lab.Bias % = Lab Mean - Consensus Group mean *100 / Consensus Group mean

Mode

• Evaluate laboratory performance: By comparing a laboratory's results to the mode, EQA providers can assess their performance and identify potential deviations or biases
• Set target values: The mode can serve as a target value for laboratories to strive for, ensuring that their results are consistent with peer group performance
• Monitor trends: Tracking changes in the mode over time helps EQA providers detect shifts in laboratory performance or instrument drift
• Improve quality: By analyzing the mode and associated data, EQA providers can identify areas for improvement and implement measures to enhance laboratory quality

Why Analysis of EQAS Reports is Important

• Proper analysis of EQAS testing results can reveal problems even before failure in EQAS or even an adverse patient result
• Recognizing patterns from graphs
• Review both the present cycle results as well as performance from previous cycle for the same analyte
• Graphs of Z score or SD or RMZ or % deviation for trends

How to Recognize Problems

• Results may consistently be different from the target peer group mean - All results on one side of the mean (may be close to mean or at variable distances from mean) Systematic Error
• Majority of results are close to the target value but some show larger deviations on one side or both sides of mean – Random Error
• Reasons and hence corrective action differs

This quiz covers the concept of External Quality Assessment (EQA) in laboratory testing, including its importance and methods for evaluating laboratory performance.