Laboratory Quality Control. Ppt
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Transcript of Laboratory Quality Control. Ppt
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