QUALITY ASSURANCE IN A MEDICAL LABORATORY

Gift Ajay SamSr. Demonstrator (Quality Management)

Department of Transfusion Medicine and ImmunohaematologyChristian Medical College, Vellore

Overview

• Introduction to Quality• What is Quality?• What is Quality Management?• The core value

• Quality assurance• Quality control• Proficiency testing• Calibration• Delta check• Inter instrument and Inter person comparison

Quality?

• Conformance to requirements_ Philip Crosby.• Exceeding what customers expect form service_ Paraguan and Berry.• User based, product based, manufacturing based, value based and

transcendent view_ Gravin.

Quality“Quality is the degree to which a set of inherent characteristics fulfils requirement”_ ISO 9000

Quality Management

• Quality: Fulfilling customer specifications.• Management:

• Plan• Organize• Staff• Lead/ direct• Control

Quality + ManagementPlan, organize, staff, lead and control to fulfilling the requirements of the customer (patient/ lab service user).

Core values of Quality Management

• Customer (lab service users) focus• Initiation from top management• Involvement of all staff• Process approach (profit maximization by waste minimization)• System approach to management (Management of interrelated

processes)• Kaizen (Continual improvement)• Factual approach for decision making• Mutually beneficial supplier relationship

Components of the quality management system• Documents and records• Organization and management• Personnel• Equipment• Purchase and inventory• Process control

• Pre analytical• Analytical- Calibration, QC, PT/EQA, maintenance• Post analytical- Delta check, inter instrument comparision

Components of the quality management system• Information management• Occurrence management• Assessment• Process improvement• Service and satisfaction• Facilities and safety

Quality AssuranceThe goal of a quality assurance program is to systematically monitor and evaluate the quality and appropriateness of test results.

Quality assurance vs Quality controlQuality Assurance Quality Control

1 Management system to guarantee integrity of data.

Measurement used to check quality of analytical data.

2 Everybody’s business Restricted to a specific area and performed by authorized staff.

3 Goal is value addition Goal is error prevention

4 Management strategy Error detection methodology

Quality control

• Selection• Cover the analytical measurement range e.g. low, normal and high.• Product stability over a long period of time

• Frequency• Stability of method (QC at least once in 24 hr or more if manufacturer or lab

determines so. (CLSI regulation, section 493.1256)• Risk of harm to patient

• Clinical action that can be taken before error could be detected.• Frequent QC can identify methodological problems earlier.

• Number of results to be repeated in case of failure.

Quality control

• Evaluation• Also called as statistical QC• Most common- Shewart Chart/ Levey Jennings chart/ run chart

• Mean is the target value• 1s, 2s, 3s are imprecision of the method• + 1S- 68.3%, + 2S- 95.4%, + 3S- 99.7%

• Over a period of time permits assessment of a method performance and detection of trends.

Interpreting data off a control chart

• Extreme- 1- 3S• Bias- 9 or more values fall on one side of the chart.• Trend- 6 or more points increasing or decreasing.• Oscillation- opposite direction over and over again.• On edge- 2 or 3 points are more than 2S from the mean in the same

direction.• Tendency- 4 or 5 points are more then 1s in the same direction.• Blissful ignorance- more than 15 points in a row within 1s of the

mean.

Establishing QC target and SD

• Why?• Detect measurement defects that are large enough to have a impact on lab

results.• Minimize the frequency of false alerts.

• How?• Instrument should be calibrated.• Assigning and updating the QC mean from a minimum of 20 runs done on 20

different days.

When QC errors are detected

Calibration

• Performed using a calibrator.• Calibrator results are traceable to the highest order of reference

system.• Calibrators for instruments are usually provided by the manufacturer

themselves.• CLIA regulation 493.1255 recommends methods have to be calibrated

or calibration verification at least every 6 months or more frequentlyif recommended by the manufacturer.

Calibration verification

• IVD manufactures can assign target values to a calibrator that automatically corrects for matrix related bias that may be present.

• Therefore, recalibration may introduce small changes in the analytical system that might contribute to long term variability in method performance.

• A measurement procedure should be calibrated only when evidence indicates that the current calibration in no longer valid.

Proficiency testing

• Evaluating method performance by comparison of results with otherlaboratories on the same set of samples.

• Goal of PT/ EQA• Result harmonization among peers• Method accuracy (Need for calibration or any other form of correction to

ensure accurate results).

Lab Report verification

• Delta check• Analytical errors• Mislabelled samples• Samples diluted with Ivey fluids

• Inter instrument comparison• Harmonization of results among instruments.

• Inter person comparison • Harmonization of results among personnel.

Other terminology

• Reference range:• Establishing a range of values within which majority of healthy people will fall,

excluding the diseased.• Accuracy:

• Trueness of measured value.• Precision:

• Repeatability of measured value• Analytic sensitivity

• The lowest value that can be reliably detected• Specificity:

• Ability to identify the presence of an analyte of interest beyond the presence of endogenous interference.