Quality Control Notes

Course Overview

  • Course Name: Quality Control
  • Course Number: 140501463
  • Credits: 1
  • Instructor: Dr. Omar Abuyaman
  • Department: Medical Laboratory Sciences
  • Description: Function of quality control (QC) in maintaining accuracy in laboratory methods over time.

Key Terms and Definitions

  • Control Materials: Substances used to ensure test accuracy.
  • False Rejections: Incorrectly identified erroneous results.
  • ISO 9000: Standardization in quality management systems.
  • Lean Production: Systematic method for waste minimization.
  • Proficiency Testing: Assessment of laboratory's performance against known standards.
  • Quality: Degree to which a set of inherent characteristics fulfill requirements.
  • Quality Control: Measures put in place to ensure test accuracy.
  • Quality Assessment: Evaluation of the validity and reliability of testing methods.
  • Quality Laboratory Process: Framework for ensuring testing accuracy and reliability.
  • Six Sigma Process: Business strategy for improvement and quality control.
  • Standard Deviation Interval: Measure of the dispersion of a set of data.
  • Total Quality Management (TQM): Organizational approach to continuous improvement of quality.
  • Westgard Multirules: Statistical rules to evaluate QC data.

Types of Errors in Quality Control

  • Pre-Analytical Errors: Occur before laboratory analysis (e.g., sample collection, patient preparation).

    • Improper patient preparation (e.g., fasting requirements).
    • Improper sample collection (e.g., hemolysis).

  • Analytical Errors: Occur during the analysis phase (e.g., equipment malfunction).

    • Sample labeling and preparation issues.

  • Post-Analytical Errors: Occur after analysis (e.g., reporting incorrect results).

    • Incorrect report delivery or interpretation issues.

Control Materials Use

  • Essential for monitoring analytical bias.
  • Random vs. Systematic Errors:
    • Random Errors: Unpredictable; minimize with repetition.
    • Systematic Errors: Consistent bias; correctable.

Control Charts in Laboratories

  • Utilized to monitor test results over time.
  • Important for spotting trends and shifts in data.
    • Shifts: Results clustering on one side of the mean over time.
    • Trends: Gradual increase or decrease over time.

Internal vs External Quality Control

  • Internal Quality Control (IQC): Daily monitoring of test results.
  • External Quality Assessment (EQA): Comparison of results with other laboratories to assess performance.

Frequency of Quality Control Testing

  • Regular testing ensures continuous method stability and accuracy.
  • Determination of testing frequency should depend on laboratory standards and regulations.

Method Evaluation in Clinical Laboratories

  • Compare different testing methods.
  • Assess performance characteristics, e.g., sensitivity and specificity.
  • Conduct interference studies to identify potential external impacts on results.

Statistical Concepts for Quality Control

  • Gaussian/Normal Distribution: Symmetrical distribution of values.
  • Measures of Central Tendency: Mean, median, mode usage in data analysis.
  • Standard Deviation (SD): Measure of dispersion around the mean; affects quality control strategies.
  • Coefficient of Variation (CV): Standard deviation as a percentage of the mean.

Diagnostic Sensitivity and Specificity

  • Sensitivity: True positives / Affected persons. Measures ability to correctly identify those with the condition.
  • Specificity: True negatives / Non-affected persons. Measures ability to correctly identify those without the condition.

Analytical Performance Characteristics

  • Analytical Sensitivity: Ability to detect small quantities.
  • Analytical Specificity: Ability to measure only the analyte of interest.

Conclusion

  • Effective quality control is crucial for accurate and reliable laboratory results. Understanding these concepts is essential for laboratory professionals to maintain high standards in testing and patient care.