QA

• Quality Assurance


  Planned and systematic activities implemented in a quality system so that quality requirements for a product or service will be fulfilled
• Quality Assurance


  The means by which reliability, precision, and accuracy of investigations used in support of optimal patient care are achieved
• Quality Assurance


  To minimize errors in the preanalytical, analytical, and post analytical phases of testing
• Stages of Quality Assurance

  1. Pre Analytical Phase

  2. Analytical Phase

  3. Post Analytical Phase
• Pre Analytical Phase


  • Before testing process
  • Process from the time a laboratory request is made until the sample is ready for testing
  • All the steps that take place before a samples can be analyzed
  • Order request, sample collection, transport and storage
  • Most errors in the laboratory is due to pre analytical phase
• Errors in Pre analytical Phase

  • Handwriting not legible
  • Inadequate volume or Incorrect specimen preparation
  • Wrong patient identification
  • Invalid specimen (Hemolyzed or Diluted)
  • Incorrectly interpreted laboratory request
  • Collected at wrong time
  • Special requirements not specified
  • Improper transport conditions
  • Incorrect tube or wrong specimen container
  • Improper patient preparation and identification
  • Incorrect patient ID
  • Improper labelling of specimens
• Analytical Phase


  • Testing process
  • Analysis stage of testing
  • Testing processes and procedures are performed
  • Quality Control
  • Maintenance and Service
• Errors in Analytical Phase

  • Instrument not calibrated correctly
  • Instrument precision problem
  • Improper incubation or timing
  • Interfering substances present
  • Specimen mix-up / carry-over
  • Oversight of instrument flags
  • Incorrect volume of specimen and reagent
  • Out of control quality control result
  • Wrong assay performed
• Post Analytical Phase


  • After testing process
  • Reporting of results
  • Result validation
  • Data management
  • Reporting
  • Treatment of patient
• Errors in Post Analytical Phase

  • Previous values not available for comparison
  • Incomplete results
  • Report not legible
  • Verbal reporting of results
  • Delayed results
  • Instrument: LIS Compatibility
  • Wrong transcription of patient's data and result
  • Confusion about reference ranges
  • Critical value reporting

  
• Quality Control


  Periodic examination of a measurement procedure to verify that it is performing according to pre established specification
• Quality Control


  It is a system of ensuring precision and accuracy in the laboratory using quality control reagents in every series of measurements
• Quality Control

  Procedure that is performed daily in the laboratory, including QC of reagents, electronics, and robotics
• Purpose of Quality Control

  • To check the stability of the machine
  • To check the quality of reagent
  • To check for technical error committed by the operator
• Accuracy


  Measure of how close a measurement is to the correct or true value
• Precision


  Measure of how close a series of measurements are to one another
• Importance of Accuracy and Precision in the Laboratory

  Measurement of accuracy and precision is being compared to the "maximum allowable error", maximum amount of error that is acceptable if the measurement is imprecise or inaccurate
• Importance of Accuracy and Precision in the Laboratory


  If the imprecision or inaccuracy exceeds the maximum allowable error, measurement is unacceptable
• Random Error


  • Caused by random variation, slight, inevitable inaccuracies in measurement or technique
  • Unpredictable and does not introduce bias
  • Varying differences between repeated measurements leading to imprecision of measurements
  • Measured using: Standard Deviation, Coefficient of Variation

  
• Systematic Error


  • Caused by variations that can distort data in one direction
  • Predictable and can introduce bias
  • Measure of agreement between measured and true value leading to inaccuracy
  • Measured using: Mean

  
• Imprecision


  • Dispersion of results for repeated measures
  • Standard deviation: measure of expected imprecision in a procedure when performed correctly

  
• Systematic Bias


  • Difference between observed mean and expected value of QC material
  • Due to changes in calibration
  • Eliminated through correct calibration
• Calibration


  • Comparison of instrument measurement or reading to a known physical constant
  • Key component in achieving quality results
  • Calibration is performed before quality control to set the standards of testing
• Quality Control Materials


  • Specimens that resemble human sample which are used to generate quality control data
  • Provided by manufacturers or created in the laboratory
  • QC results are examined to check if procedure meets performance requirements appropriate for patient care
  • Drawn from pool of samples
  • Freeze dried to allow long term stability
  • Aliquot is prepared in reconstitution
  • Prepared control is analyzed by patient samples
  • Data is analyzed statistically to monitor trends or reliability
• Forms of QC Materials

  • Lyophilized Control Solution (Powdered)
  • Frozen Control Solution
• Characteristics of QC Materials

  • Resemble human samples
  • Inexpensive and stable for long periods
  • Non communicable disease
  • No matrix effects/know matrix effects
  • With known analyte concentrations
  • Convenient packaging for easy dispensing and storage
  • Stored at ref temp ( 2-8 ° C)
• How to Perform Quality Control

  1. Run the control samples in the same manner of running patient samples

  2. Control result that falls within the defined limits of acceptability

  3. Report control results

  4. Proceed with running of patient samples
• How to Perform Quality Control - Out of Control

  1. Run the control samples in the same manner of running patient samples

  2. If out of control, rerun the control

  3. If the result is still out of control, use a new control. Rerun the new control

  4. If still out of control, recalibrate the machine. Use a new control. Rerun the new control

  5. If results are still out of range, call the engineer or product specialist
• Levy-Jennings Chart


  • Used to simplify the review of quality control data
  • Graphical representation of QC results over time
  • Displays the outliers, trends, and shifts in the data, with the ultimate goal of showing whether an analytical method is working properly
• Outlier


  Points that lie outside the acceptable range
• Trend


  Gradual movement in one direction, either upward or downward, by a set of 6 or more consecutive data point
• Shift


  An abrupt move in which 6 or more consecutive data points all occur above or below the mean
• Westgard Multirules


  • 12s
  • 13s
  • R4s
  • 22s
  • 41s
  • 10x̅
• Intralab Quality Control (Internal QC)


  • Occurs inside the lab
  • Analyses of control samples together with the patient specimens
  • Important for the daily monitoring of accuracy and precision of analytical methods
  • Detects both random and systematic errors in a daily basis
  • Uses Levy-Jennings/Shewhart chart
• When is Internal Quality Control Performed?

  1. Beginning of shift

  2. Before testing patient samples

  3. When reagents are changed

  4. Instrument malfunction has occurred

  5. Test results are questioned by healthcare provider

  
• External Quality Control


  • National Reference Laboratory (NRL) is involved
  • Involves proficiency testing programs that provide samples of unknown concentration to participating clinical laboratories
  • Long term accuracy of the analytical methods
  • Uses Youden/Twin plot
• External Quality Control Testing

  1. Proficiency testing

  2. Series of unknown samples are sent to the laboratory from the reference laboratory

  3. Unknown samples must be tested by the laboratories who perform the analysis of specimens using the same reagents and equipment

  4. Results are submitted to the program provider as soon as the analysis is done

  5. Unknown samples must be treated like a patient specimen to determine the true essence of accuracy
• Interpretation of Proficiency Testing

  • Difference of greater than 2SD in the results: Lab is not in agreement with the rest of the labs included in the program
  • In case lab failed to identify or resolve the error or discrepancy, facility is at risk of continuous operation