Quality control ppt BIOCHEMISTRY

QUALITY CONTROL Dr. Vijay Marakala MD

QUALITY CONTROL. QUALITY CONTROL.

Quality management

Quality assurance

Quality control

Three principles of clinical lab

What is Quality?

Quality defined as conformance to the

requirements of users or customers

Total quality management of the clinical lab

Quality planning

Quality lab process

Quality control

Quality assessment

Quality improvemen

t

Quality Control

Quality control

Emphasizes statistical and nonstatistical check procedures

Able to detect the problems early enough to prevent their consequences

Techniques and procedures that monitor performance parameters

Prerequisite for an effective lab service

Promotion of quality control and continuous

improvement of the total testing process, including

preanalytical and postanalytical phases

Test is requested by physician and ordered on the computer. Barcode is generated Specimen is collected

Specimen and order are transported to the lab

The specimen is accessioned in the lab

The specimen is processed

The specimen is analyzed

The results are reviewed and verified & dispatched

Steps in obtaining a laboratory test

Lab testing processes and their potential errors

Test ordering Specimen acquisition

Analytical measuremen

t

Test reporting

Test interpretatio

n

Test ordering

Inappropriate testHandwriting not

legibleWrong patien

t identificatio

n

Specimen acquisition

Analytical measurem

entTest

reportingTest

interpretation


Test ordering

Specimen acquisitionIncorrect tube

Incorrect

patient identific

ationInadequ

ate volumeCollecte

d at wrong time

Improper

transport

conditions

Analytical measurem

entTest

reportingTest

interpretation


Test ordering


Analytical

measurement

Instrument not calibrat

ed correctl

ySpecimen mix-

upIncorre

ct volume

of specim

enInterferi

ng substan

ce presentInstrum

ent precisio

n proble

m

Test reporting

Test interpreta

tion


Test ordering


Analytical measurem

ent

Test reporting

Wrong patient identificationReport

not legibleReport delaye

dTranscription error

Test interpreta

tion


Test ordering


Analytical measurem

ent

Test reporting

Test interpretationInterferin

g substance

not recognize

dSpecificity

of the test not

understood

Precision limitation

s not recognize

dAnalytical sensitivity

not appropria

tePrevious

values not

available for

comparison


Elements of a QA/QC Program

Commitment

Facilities and resources

Technical competenceTechnical procedures

Problem solving mechanisms

Quality Control: Technical Procedures

Control of preanalytical variables

Control of analytical variables

Control of analytical quality using statistical methods and control charts

Test requests

Patient preparation

Patient identification


Control of preanalytical variables

HOW TO CONTROL THESE ERRORS?

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.

PRE ANALYTICAL VARIABLES



Transcription error 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. • Blood collection from an arm into which an intravenous infusion is running.

Hemolysis during blood collection

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

• The identification of the person collecting a specimen should be maintained • Clinicians should be encouraged to report clinically inconsistent results.

Analytical methodology

Standardization

Calibration procedures

Documentation of analytical protocols

Monitoring of critical equipment and materials

Control of analytical variables


CONTROL OF ANALYTICAL VARIABLES

Many analytical variables

• Water quality• Calibration of volumetric glassware and pipets• 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



Using stable ‘controls’

• Values cover medical decision points • Similar to the test specimen (matrix)• Available in large quantity• Stored in small aliquots• Ideally, should last for at least 1 year

QC material- Preparation & Storage

Precautions to be followed

• Reconstitute lyophilized material carefully & strictly as per label direction• Frozen sample to be thawed properly. After attaining room temp., mix slowly

by inversion and then use.• Storage temperature to be strictly followed

QC material Availability

Assayed

Unassayed

Level 1 , 2 and 3



Using ‘Calibrators’

• Have a known concentration of the substance (analyte) being measured • Used to adjust instrument, kit, test system in order to standardize the assay• Sometimes called a standard, although usually not a true standard • This is not a control

Quantitative Aspects of QC

External Q C

Internal Q C

Internal Q C

Day to day internal QC programme

Is a most useful tool

For maintenance of long term Consistency ( Accuracy ) control

Long term Precision control of analytical method

Internal Q C monitors a single lab

External Q C

Provides independent validation of internal QC program

Gives valid estimation of long term accuracy of analytical system

Compares performance of different labs

Control of analytical quality using statistical methods and control charts

Statistical methods

Mean, SD, CV

Accuracy

Precision

Control charts

Levey-Jennings Control Chart

Westgard multirule chart

Shewhart SD control chart

Good Accuracy Good Precision

Good Precision Only

Neither Good precision Nor Accurate

Frequency of observation

Control limit

Control limit

Stable performance Accuracy problem Precision problem

Obs

erve

d co

ntro

l con

cent

ratio

n

l

Time

Control limit

Control limit

Stable performance Accuracy problem Precision problem

Obs

erve

d co

ntro

l con

cent

ratio

n

Levey-Jennings Control Chart

Trends & Shifts

Run numbers

Obs

erve

d co

ntro

l con

cent

ratio

n

Mean

+1s

+3s

+2s

-2s -1s

-3s

Westgard Multirule Chart

0 1 2 3 4 5 6 7 8 9 10………………………………………30

Run numbers

Obs

erve

d co

ntro

l con

cent

ratio

n

Mean

+1s

+3s

+2s

-2s -1s

-3s


0 1 2 3 4 5 6 7 8 9 10………………………………………30

12sWarning rule

Run numbers

Obs

erve

d co

ntro

l con

cent

ratio

n

Mean

+1s

+3s

+2s

-2s -1s

-3s


0 1 2 3 4 5 6 7 8 9 10………………………………………30

13sRejection rule

Run numbers

Obs

erve

d co

ntro

l con

cent

ratio

n

Mean

+1s

+3s

+2s

-2s -1s

-3s


0 1 2 3 4 5 6 7 8 9 10………………………………………30

22sRejection rule

Run numbers

Obs

erve

d co

ntro

l con

cent

ratio

n

Mean

+1s

+3s

+2s

-2s -1s

-3s


0 1 2 3 4 5 6 7 8 9 10………………………………………30

R4sRejection rule

Run numbers

Obs

erve

d co

ntro

l con

cent

ratio

n

Mean

+1s

+3s

+2s

-2s -1s

-3s


0 1 2 3 4 5 6 7 8 9 10………………………………………30

Rejection rule41s

Run numbers

Obs

erve

d co

ntro

l con

cent

ratio

n

Mean

+1s

+3s

+2s

-2s -1s

-3s


0 1 2 3 4 5 6 7 8 9 10………………………………………30

Rejection rule10 x

CUSUM Control Chart

Control of analytical quality using patient data

Clinical correlation of test results Correlation with other lab tests

References

• Tietz test book of clinical Biochemistry• Varley• Kaplan• Internet

Quality control ppt BIOCHEMISTRY

Health & Medicine

Transcript of Quality control ppt BIOCHEMISTRY