P.ModaganFinal Year M.sc, Medical

Biochemistry

Definition

QC is a technique used to detect and correct errors before they result in defective product or service. QC refers to the measures that must be included during each assay run to verify that the test is working properly.

When a laboratory management is committed to meet a patients need, this is done through an ongoing program of total quality management program

Total quality management may be referred to as:

Total quality control

Total quality leadership and

Continuous quality improvement or

Quality management system

Total quality management framework

Quality laboratory process (QLPS)

Quality Assurance (QAS)

Quality assessment (QC)

Quality control (QC)

Quality laboratory process

QLPS includes analytical process as well as general policies, practices and procedures that define how all aspects of work get done.

Quality assuranceQuality assurance means quality

enhancementQuality assurance aims at ensuring that

the data provided are reliable and relevantQuality assurance involves all measures

that can be taken to improve laboratory efficiency and effectiveness

It ensures laboratory performance with minimum risk for laboratory workers and gives maximum benefit to the individual and community

Quality assurance includes:

Clinical usefulness of selected testsPatient preparationSamplingSpecimen handlingPreservation and storageTransportIdentification and data processing which

includes reporting of results

Elements of quality assurance commitment:

Dedication to quality service must be centralA true commitment is required by lab

directors, managers and supervisors, if the efforts of the lab personnel are to be successful

Facilities and resources

Quality services are developed and maintained on the basis of the following:

Adequate space Modern materials and equipments Adequate stock of requirements and supplies Adequate staffing Budgetary resources Proper supervision

Technical competence

Educational background and experience of personnel are important

High quality personnel can render high quality services.

In service, training is also needed, which can help develop and maintain skills

Technical procedures

Good technical procedures are necessary in the following criteria:

Preanalytical variables Analytical variables Post analytical variables

Quality Assessment

Also known as proficiency testingQuality Assessment is a means to determine

the quality of the results generated by the laboratory

Quality Assessment is a challenge to the QA and QC programs

Quality control

The aim of quality control is to ensure that the results generated by the test are correct

QC emphasizes statistical control procedures and also includes reagent and standard checks, linearity checks, etc..

Preparation of the quality control materialThe serum samples are collected

Pooled serum samples together ( 1-2 litres )

Screen the serum sample for various infective diseases

Adjust the PH to 7.5 using concentrated sulphuric acid

Distribute 10 ml portions of this into several plastic vials and store in the deep freezer and this is stable for 3 months

Each day 1 vial is taken and bring it in to room temperature, once it liquefies analyze the value

Enter the value on the quality control chart

If the value on a specific day falls within ± 2 SD that indicates all the reagent and standard are good

In case the value is above or below ± 2 SD indicates reagent or standard is deteriorated

Repeat the assay with fresh reagent and standard

Quality control systemInternal quality control

The internal quality control can be maintained by going through a complete checklist of items to make sure that all laboratory systems are being monitored and in control.

This checklist includes:Maintenance of equipments and glassware.Quality control of reagents, standards, control

materials and reference ranges.Method selection and evaluation.

Definition:

Accuracy

Precision

SD

• Standard deviation - extent of random variation

• SD = d2

n-1

d= difference of individual result from mean

n= number of observations

CV

Co-efficient of variation relative magnitude of variability while

comparing two procedures

CV % = (SD x 100)/mean

ACCURACY AND PRECISION

Good Accuracy Good Precision

Good Precision

Only

Neither Good precision Nor Accuracy

Levey-Jennings Control Chart

External quality controlExternal quality control is a way to compare the

performance of a laboratory with reference to other laboratories.

Also known as proficiency surveys.

Such proficiency testing programmes periodically provide samples of unknown results to participating laboratories.

• When a laboratory receives such a sample, it must analyze and return the results within a specified period of time for comparison with the results obtained from other laboratories participating in the proficiency survey.

FIVE ‘Q’ Framework

Quality Planning

Quality Lab Processes

Quality ControlQuality Assessment

Quality Improvement

“PDCA” cycle

QP- provides the planning step

QLP- establishes standard process

QC and QA –provides measures for checking how well things are done

QI- provides mechanism for acting on these measures    

LABORATORY TESTING PROCESSES AND THEIR POTENTIAL ERRORS

  PRE ANALYTICAL ERRORS PROCESS POTENTIAL ERRORS Test ordering inappropriate test

Handwriting not legibleWrong patients IDSpecial requirements not specified

 Specimen acquisitionIncorrect tube or containerIncorrect patient IDInadequate volumeInvalid specimen (hemolysed or diluted) Collected at

wrong timeImproper transport conditions

ANALYTICAL ERRORS

 Analytical Instrument not calibrated Measurement correctly

Specimens mix – upIncorrect volume of specimenInterfering substances presentInstrument precision problem

Test reporting Wrong patient IDReport not legibleReport delayedTranscription error

POST ANALYTICAL ERRORS Test interpretation: Interfering substance not

recognized

Specificity of the test not understood

Precision limitation not recognized

Analytical sensitivity not appropriate

Previous values not available for comparison

HOW TO CONTROL THESE ERRORS?

 PRE ANALYTICAL VARIABLES   Requires the coordinated effort of many

individuals and hospital departments  Patient Identification   The highest frequency of errors occurs with the

use of handwritten labels and request forms. The use of bar code technology has significantly reduced ID problems.

Turnaround timeDelayed and lost test requisitions, specimens and reports can be major problems for labs. Recording of the actual times of specimen collection, receipt in the lab and reporting of results with use of computers will solve these problems.

Transcription error  A substantial risk of transcription error exists from

manual entry of data even with the double checking of results, computerization will reduce this type of transcription error.

 Patient preparation•  Lab tests are affected by many factors, such as,• Recent intake of food, alcohol, or drugs • Smoking• Exercise• Stress• Sleep• Posture during specimen collection

The lab must define the instructions and procedures compliance with these instructions can be monitored directly efforts should be made to correct non compliance

Specimen Collection

•  Prolonged tourniquet application causes local anoxia to cells and excessive venous backpressure, venous stasis and hemoconcentration.

•  Blood collection from an arm into which an intravenous infusion is running can be diluted or contaminated.

• Hemolysis during blood collection• Improper containers with incorrect preservatives

•  To monitor and control these problems, specially trained lab team assigned to specimen collection

• The identification of the person collection a specimen should be maintained  

 Specimen transportThe stability of specimens during transport from the patient to the lab is seldom monitored

CONTROL OF ANALYTICAL VARIABLES

• Water quality

• Calibration of analytical balances

• Calibration of volumetric glassware and

pipettes

• Stability of electrical power

• Stability of temperature of heating baths,

refrigerators, freezers and centrifuges

The procedure Manual should contain the following:

• Procedure name• Clinical significance• Principle of method• Specimen of choice• Reagents and equipments• Procedure• Reference values• Comments• References

Reference value

Definition:

A value obtained by observation or measurement of a particular type of quantity on a reference individual

Establishment of reference valuesAll groups of reference individuals should be

clearly defined

The patient examined should resemble sufficiently the reference individuals in all respects other than those under investigation

The conditions under which the samples were obtained and processed for analysis should be known

All quantities compared should be of the same type

All laboratory results should be produced with the use of adequately standardized methods under sufficient analytical quality control

The diagnostic sensitivity and specificity, prevalence and clinical costs of misclassification should be known for all laboratory tests used

Related terms Reference individual ↓ Reference population ↓ Reference sample group ↓ Reference value ↓ Reference distribution ↓ reference intervals`

Health associated reference valueRisk factor :Obesity HypertensionRisk from occupation of environmentGenetically determined riskIntake of pharmacologically active agent : Drug treatment for disease Oral contraceptives Drug abuse Alcohol Tobacco

Contd..

Specific physiological status : Pregnancy Stress Excessive exercise

Possible partitioning factors :AgePosture when sampledBlood group (ABO)RaceCircadian variationSexDietStage of menstrual cycleEthnic background

Contd..

Stage of pregnancyExerciseTime of the day when sampledFasting or non fastingUse of tobaccoGeographical location

Use of reference valuesDiagnosis of diseaseScreening for diseaseDetermination of severity of the diseaseMonitoring progress of diseaseMonitoring response to therapyMonitoring drug toxicityPredicting response to treatmentPredicting prognosisReassurance to patients