Quality Control

Quality

• In business, it can mean conformance to the requirements of the users/customers

• In laboratory, can mean patient satisfaction

Quality Assurance

• A complete system of creating and following procedures and policies

• ○ To aim for providing the most reliable patient laboratory results, and

• ○ To minimize errors in the pre-analytical, analytical, and post analytical phases Covers all standard operating procedures (SOP) that aim to provide the most reliable patient results and at the same time that aims to reduce errors that may occur in the laboratory, considering the three (3) phases of the testing process

• Falls under quality assurance

• Under the umbrella of a larger system, which is quality assurance

• A system of ensuring accuracy and precision in the laboratory by using quality control materials in every series of measurement

• Before running patient samples (when working on CC section), it is important to run quality testing, to ensure accuracy and precision in the laboratory

Quality Control

• To check the stability of the machine that produces laboratory result

• In QC, the materials being utilized for quality control purposes are called Quality Control Materials

• The materials being used for the sole purpose of calibrating machines/equipment in laboratory are called Reference Materials

• Standards and Standard Solutions

Quality Management

• Also called Total Quality Management (TQM)

• Refers to the overall process used to ensure that laboratory results meet the requirements for health care services to patients

• QM/TQM covers all procedures necessary to ensure that quality health services are received by our patients

• ● Documents and records of the patients

• ● Organization of the laboratory

• ● Personnel who work in the laboratory

• ● Equipment/Analyzer we utilize for laboratory testing

• ● Purchasing and inventory of supplies or equipment

• ● Process control

QMS Components

• Preanalytical

• Analytical

• Postanalytical

• Information management

• Occurrence management

• Assessment

• Process improvement

• Service and satisfaction Facilities and safety

List of Process Controls

Calibration

using standards or standard solution

Maintenance procedures

troubleshooting mechanism you need to perform in the laboratory should your analyzer failed to release results within the control limits

• Calibration

• Maintenance procedures

• Quality Control

• Proficiency testing/ External Quality Assurance

All process under analytical

Control Limits

the range of acceptable upper and lower value

Quality Control

So that when values fall within the control limits, it is not just about establishing a control limit, you should know how to interpret when values go outside or within the control limits

The Analytic method is properly reporting values

What does it mean if Values fall within the control limits?

Identify possible problems and do corrective measures

What if Values fall outside the control values?

±2SD

Ideal control limit is ____

Levey and Jennings 1950

First individuals that applied the principles of analyzing QC in the laborator

Quality Control materials (Control Solutions)

are specimens analyzed for QC purposes

Available in sufficient quantity to last at a year

Aliquot

sample from a total volume of the control solution

lyophilized

Most commercially prepared QC materials are ______

Lypholized

, they come in pulverized or powdered form so that reconstitution is neede

Reconstitution

you have to add the necessary diluent to come up with a homogenous mixture of the control solutio

Normal Control (Level 1)
Abnormal Control (Level 2)

2 levels of control in general chemistry assay

Low Control (Level 1)

Normal Control (Level 2)

High COntrol (Level 3)

3 levels of control in Immunoassay

• To check the stability of the machine

• To check the quality of the reagents

• To check technical (operator) errors

Objectives of Quality Control

Upper limit or lower Limit

In CC lab, we have range as limits of variations

Finding cause
Taking corrective action

Role of MEdical technologist when actions is needed for remedy of errors

Intralab Quality Control (Internal QC)

KINDS OF QUALITY CONTROL

• Involves the analyses of control samples and the patient specimen; use for the daily monitoring of accuracy and precision of analytical methods

• Internal QC: in the laboratory itself

Interlab Quality Control (External QC)

KINDS OF QUALITY CONTROL

• Involves proficiency testing programs that periodically provide samples of unknown considerations to participating laboratories; important in maintaining long-term accuracy of analytical methods

• To determine state-of-the-art interlaboratory performance

College of American Pathologists (CAP) proficiency program

gold standards for clinical laboratory external QC testing

Quality Assurance

encompasses all activities performed by laboratory personnel to ensure reliability of test results.

Internal Quality Assurance System

MAJOR COMPONENT OF QUALITY ASSURANCE

• includes day-to-day activities that are undertaken in order to control factors or variables that may affect test results

External Quality Assurance System

MAJOR COMPONENT OF QUALITY ASSURANCE

• A system for checking performance among clinical laboratories and is facilitated by designated external agencies.

Department Order No. 393-E s. 2000

What Department order did NEQAS gave the five institution designated for NRL

Research Institute for Tropical Medicine (RITM)

NRL for

• Microbiology (identification and antibiotic susceptibility testing) and Parasitology (identification of ova and quantification of malaria)

San Lazaro Hospital /STD-AODS Cooperative Central Laboratory (SLH/SACCL)

NRL for

• Immunology/Serology

• HBsAg, HIV, HCV

National Kidney and Transplant Institute (NKTI)

NRL for

• Hematology and Coagulation

Lung Center of the Philippines (LCP)

NRL for

• Clinical Chemistry

East Avenue Medical Center (EAMC)

NRL for

• Toxicology, Occupational and Environmental Health and Micronutrient Assay.

• Drugs of abuse

• Laboratory can be a candidate for closure

• Thus, see to it first that all your intralab results (internal QC) are within the control limits in order for the NEQAS to be goof

What if all analytes tested are outside the control limits?

• You are releasing results that are accurate and precise

What if all analytes tested are within the control limits?

• Glucose

• Blood Urea Nitrogen (BUN)

• Creatinine

• Uric Acid

• Cholesterol

• Total Protein

• Albumin

• Sodium

• Potassium

• Chloride

10 ANALYTES BEING QUANTIFIED FOR NEQAS CLINICAL CHEMISTRY

Sensitivoity

PARAMETERS OF QUALITY CONTROL

• Ability of the analytical method/process to detect the smallest concentration of analyte of interest

• The kit can detect the slightest concentration of an analyte present in a sample

Specificity

PARAMETERS OF QUALITY CONTROL

• Ability of the analytical method/process to detect the smallest concentration of analyte of interest

• The kit can detect the slightest concentration of an analyte present in a sample

Accuracy

PARAMETERS OF QUALITY CONTROL

• Nearness or closeness of the results to the true or target value

• In Clinical Chemistry, we’re not taking abnormal, normal, positive or negative, we release results by value

• We may not come with definite or the same numbers but as long as it is close to target value, we can say it’s accurate

Precision or Reproducibility

PARAMETERS OF QUALITY CONTROL

• Ability of an analytical method to give repeated results on the same sample that agree with one another

• When we keep repeating this test using the same procedure, the same reagent, we will be able to duplicate or come up with results that would agree with one another

• Closeness of the assayed value to the repeated value

Practicability

PARAMETERS OF QUALITY CONTROL

• Degree by which a method is easily repeated

• If the procedure is laborious and tedious, they tend to accept unreliable results.

Reliability

PARAMETERS OF QUALITY CONTROL

• Ability of an analytical method to maintain accuracy and precision over an extended period of time during which equipment, reagents, and personnel may change

• Even different personnel perform the tests, different reagent, equipment, we can rely on the procedure

PARAMETERS OF DIAGNOSTIC EFFICIENCY

Used to indicate/determine how good a given test is at detecting or predicting the presence of a disease

Diagnosti Sensitivity

• TP: True Positive: A patient has the disease or condition and is positive on the test

• FN: False Negative: the patient has the disease or condition but is negative on the test

PARAMETERS OF DIAGNOSTIC EFFICIENCY’

• Ability of a test to detect a given disease or condition

Diagnostic Specificity

• TN: True Negative: the patient does not have the disease or condition and is negative of the test

• FP: False Positive: the patient does not have the disease or condition but is positive of the test

PARAMETERS OF DIAGNOSTIC EFFICIENCY’

• Ability of a test to correctly identify the absence of a given disease or condition

TYPE OF ERROR

• Present in all measurements; due to chance

• type of error which varies from sample to sample.

• It is the basis for varying differences between repeated measurements — variations in technique.

• Due to instrument

• operator

• environmental conditions

• pipetting error

• mislabeling in samples

• temperature of analyzer

• improper mixing of sample or reagent

Causes of Random Error

Systematic error

TYPE OF ERROR

• Error always in one direction

• Errors that influences observations consistently in one direction

• Type of error is associated in one direction

• It is detected as either positive or negative bias

• you have to expect that the results are precise (meaning the results are

• calibration problems

• deterioration of reagents and control materials

• improperly made standard solutions

• contaminated solutions

• unstable and inadequate reagent blanks

• leaky ion selective electrode

Causes of Systematic Error

Constant Error

TYPES OF SYSTEMATIC ERROR

• The magnitude of change is constant and not dependent on amount of analyte

• Cause: interference or contamination

Proportional Error (Slope/Recent Error)

TYPES OF SYSTEMATIC ERROR

• Error dependent on analyte concentration

• Cause: poor recovery of analyte during an analysis

• Incorrect patient identification

• Improper patient preparation

• Incorrect specimen collection

• Mislabeled specimen

• Incorrect order of draw and use of tubes for blood collection

• Incorrect anticoagulant to blood ratio (short draw)

• Improper mixing of blood and anticoagulant

• Incorrect specimen preservation

• Mishandled specimen (transport and storage)

• Incorrectly interpreted/ordered laboratory test

• Incomplete centrifugation

• Incorrect data log-in

TYPES OF ERRORS ACCORDING TO THE PHASES OF LABORATORY TESTING

• PRE ANALYTICAL ERROR

• Incorrect sample and reagent volume

• Incorrect incubation of solution

• Equipment/instrument malfunction

• Improper calibration of equipment/ calibration error

TYPES OF ERRORS ACCORDING TO THE PHASES OF LABORATORY TESTING

• ANALYTICAL ERROR

• Unavailable or delayed laboratory results

• Long turnaround time

• Incomplete laboratory results

• Wrong transcription of the patient's data and laboratory results

• Missing laboratory results

• Laboratory results submitted to the wrong physician or doctors who did not request for the lab test

TYPES OF ERRORS ACCORDING TO THE PHASES OF LABORATORY TESTING

• POST- ANALYTICAL ERROR

Allowable analytical error

What does Ea mean?

RE and SE (total error) < Ea

If _________________, then the performance of the test is considered acceptable

If the error > Ea

if ________________ corrections must be made to reduce the error or the method is rejected.

Mean

• A measure of central tendency

• Termed as “average”

• Most commonly used measurement of central tendency

Standard Deviation

• The most frequently used measure of variation

• Results are actually used to determine errors in the laboratory

• A measure of dispersion of values from the mean; helps describe the normal curve

• It depends on what is being accept by each laboratory

± 2SD

Usually in CC, what is best is to accept ____, and outside than that value is far from the real mean

Coefficient of Variation (CV)

• An index of precision

• For highly precise analyzers can be less than 1%

Variance

Measure of variability

Square of SD

Gaussian Curve

(Bell-shaped curve/Normal distribution curve/Normal frequency curve

68.3

________% of the values under the normal curve is between ± 1SD

95.4

____% of the values would fall under ± 2SD control limits

99.7

_____% under the normal curve is between ± 3SD

Shewhart Levey - Jennings Chart

• It is the most widely used QC chart in the clinical laboratory

• Can apply multiple rules (Westgard rules) without the aid of the computer

• Easily identifies random and systematic errors

• Cumulative Sum Graph; Youden / Twin Plot

• Cumulative Sum Graph: gives earliest indication of systematic errors

• Youden / Twin Plot: used to determine proportional and constant errors

Others of Charts

• the analyte of interest

• the analyte of interest

• Days of running

Creation of the Shewhart Levey- Jennings Chart

• Heading –__________

• Y-Axis – ___________

• X-Axis – _________

Trend

ERRORS WHICH CAN BE OBSERVED IN THE LJ CHART

• Formed by the control values that continue either to increase or decrease for a period of six consecutive days by passing the mean

1. Values should continue to increase or decrease for a period six (6) consecutive days

2. Observed values should pass the mean

• Deterioration of Reagents

• Open new set of reagents as there might be a contamination on deteriorated agents

In order for you to determine a trend in your chart, you have to meet two (2) criteria, what are these:

Main Cause _________

Next Action __________

SHIFT

ERRORS WHICH CAN BE OBSERVED IN THE LJ CHART

• Formed by the control values that distribute themselves on one side of the mean for a period of six consecutive days

• improper calibration of the instrument

• You need to get your standard solutions and calibrate your instruments/analyzer

Shift

• Main cause___________

• Next action:________

Outliers

ERRORS WHICH CAN BE OBSERVED IN THE LJ CHART

• Are values that are far from the main set of values

• Are highly deviating values

• Caused by R/S errors

Westgard Rules/ Westgard Multirules

Also known as Westgard Multirules

These rules are used to further judge whether the control results are out of control or in control at the same time, we use this to determine the type of error that is associated with our analytic runs

Dr. James Westgard 1981

In __________ of University of Wisconsin in Madison, USA, published the six (6) Westgard rules

12s

WESTGARD RULES

• One control observation exceeds the mean ± 2SD

• A warning rule that initiates testing of control data by other rules.

• For screening purposes

13s

WESTGARD RULES

• One control observation exceeds the mean ± 3SD

• Associated with a random error

22s

WESTGARD RULES

• Two control observations consecutively exceed either the mean ± 2SD

• Allows high sensitivity to systematic error

41s

WESTGARD RULES

• Four consecutive control observations exceed either mean ± 1SD

• Associated with systematic error

R4

WESTGARD RULES

• The range or difference between the highest and lowest control result within an analytical run exceeds +2SD and -2SD

• Allows detection of random error

10x

WESTGARD RULES

• Ten consecutive control observations are on the same side of the target mean.

• This allows the detection of systematic error