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QUALITY CONTROLQUALITY CONTROL

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KEMRI-Wellcome Trust Research Programme

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Learning ObjectivesAt the end of this module, participants should be able to:

Define quality control and describe its relationship to the overall quality management system.

Describe differences in quantitative, qualitative, and semi-quantitative examinations.

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DefinitionQC is examining “control” materials of known

substances along with patient samples to monitor the accuracy and precision of the complete examination (analytic) process.

Internal Quality Control (IQC)

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refers to the set of procedures undertaken by the laboratory staff for the continuous and immediate monitoring of laboratory work in order to decide whether the results are reliable enough to be released.

Quality Assurance (QA)

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All planned and systematic actions necessary to provide adequate confidence that goods or services will satisfy the customer’s needs.

QA

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The right result,........... at theRight time,......................on the Right specimen,............ from theRight patient,................. with result interpretation

based on Correct reference data, and at theRight price

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Purpose of QC

The goal of QC is to detect errors and correct them before patients’ results are reported

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What are accuracy

and precision

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Quality Control is used to monitor the accuracy and the precision of the assay.

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Accuracy and Precision

Accurate = Precise but not Biased

Accurate and Precise

Precisebut Biased Imprecise

Quantitative QC

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Quantitative ExaminationsMeasure the quantity of a particular substance in a sample

Measurements should be both accurate and precise.

What is a Control

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material that contains the substance being analyzedinclude with patient samples when performing a test

used to validate reliability of the test systemrun after calibrating the instrumentrun periodically during testing

CONTROL vs CALIBRATORS

Calibrators Controls

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A substance with a specificconcentration.

Calibrators are used to set(calibrate) the measuring points on a scale.

A substance similar to patients’ samples that has an established concentration.

Controls are used to ensure

the procedure is working

properly.

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Preparation and Storage of Control Material

adhere to manufacturer’s instructions

keep adequate amountof same lot number

store correctly

CONTROLCONTROL

Implementation Steps Quantitative QC Procedures

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establish policies and procedures assign responsibility, train staff select high quality controls establish control ranges develop graphs to plot control values - Levey-Jennings

charts monitor control values develop procedures for corrective action record all actions taken

Qualitative QC

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Qualitative Examination Methods

Examinations that do not have numerical results: growth or no growth

positive or negative

reactive or non-reactive

color change

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Semi-quantitative Examination Methods

Results are expressed as an estimate of the measured substance:

“trace amount”, “moderate amount,” or “1+, 2+, or 3+”

number of cells per microscopic field titres and dilutions in serologic tests

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Important Concepts in Quantitative QC

sample management staff competency equipment maintenancecontrol materials stains, media and reagents managementrecord keeping

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Caring for Stains

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No AttentionContinued Attention

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Quality Control for Stains

As appropriate for particular stain: check with known organisms or cells examine for crystal shards or for precipitation examine for contaminants such as bacteria

and fungi

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Left: Wright stain

Right: Gram stain

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Stain Management

use established procedure for preparation or reconstitution

label: content, concentration, date prepared and placed in service, expiration, initials

store appropriately

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Gram Stain

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Good Quality Poor Quality

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Media Problems to Avoid

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out-dateddried-outcontaminated

Human blood should not be used because: too much batch to batch variationmay include inhibitory substances, including antimicrobialsmay contain biohazards (e.g., hepatitis virus)

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Quality Control of Growth Media keep records for media prepared in-house

record outcomes in a dedicated media logbook for:

pH, sterility, ability to support growth using stock cultures, biochemical response of stock cultures

Frequency

test each new batch or lot number

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If QC is out of control

The Good Practice is to:STOP testingidentify and correct problemrepeat testing on patient

samples and controls after correction

Do not report patient results until problem is solved and controls indicate proper performance

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Review QC dataReview QC data

Assure complete

documentation

Assure complete

documentation

Train all staffTrain

all staff

Establish written

policies and procedures

Establish written

policies and procedures

QC Program Steps

include corrective actions

THANK YOU!

Comments ……..Suggestions………..Questions

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