Quality assignment(1)

Quality Control

IT IS A BASIC SAFETY PRACTICE TO
MONITOR ANALYTICAL QUALITY OF
MEASUREMENT.

To detect changes from stable day to day
operation and eliminate reporting of results with
medically important errors.`

OBJECTIVES
1.To determine how to establish the
analytical goal and quality control
scheme /schedule in your lab
2.To identify the Quality control
charts and quality control roles
3.To identify the new rules of west
guard.
4. Overview of the CLSI guide lines
C24.
2

FIRST OBJECTIVE

To determine how to establish the
analytical goal and quality control !
scheme /schedule in your lab

3

Data we needed to design Quality
Control

1.Commercial QC material

2.Manufacturers’ kit inserts .

3. Doing it for yourself is, as usual,
the safest method.

4.EQAS programs .
4

Designing the internal quality control
protocol
Define the level of quality that the laboratory wants to.1
attain for a determined test (the analytical quality
(.specification

.know the stable analytical performance for this test . 2

a control rule (control limits and number of controls per . 3
( .run

:Assure quality of results. 4
a. analytical imprecision and bias
b. EQAS

5

Proficiency testing
# Inter laboratory Comparison Programs Help
Improve Laboratory Performance.

#

Define Analytical Goal

Two main strategies for analytical
quality specifications based on
.calculation of imprecision and bias

7

?How to establish your analytical goal

The underlying principle of ‘measurement*
uncertainty’ is that a laboratory should know how
.precisely they can measure any particular analyte

Two main strategies for analytical quality*
specifications based on biology have been
evaluated for imprecision and bias (in combination
with imprecision), respectively

8

Challenges to set analytical Goal
External Internal

Permenant
External Internal
:Method :Implementation
Permenant

:Method
Analytical principle Choice of conditions
:Implementation

Analytical Equipment
principle In house' equipment'
Choice of conditions

Reagents
Equipment ,In house' reagents'
In house' equipment'

Reagents)choice of producer( ,.Time, Temperature,
In house' reagents' Volume, etc

)choice of:producer(
Standardization .:StandardizationVolume, etc
Time, Temperature,

:Standardization :Standardization

Traceability of calibration of
Traceability calibration Calibration function
Calibration function

Variable
Variable :Batches :Batches ::Performance
Performance

)Reagents Reagents
) (variability (variability in house' reagents'
in house' reagents'

Calibrators
Calibrators ..Training, Maintenance,
Training, Maintenance, etc etc

Consumables
Consumables ''Control with 'trouble-shooting
Control with 'trouble-shooting
9
Documentation
Documentation

Relevance to customers

All these
complicated
processes to
provide the
appropriate
quality for our
patient cares

12

Setting Goals For Q.C
Performance
1.Maximum allowable number of unacceptable
results, due to an out of control error conditions.
2.Maximum allowable probability of reporting
unacceptable results.
3.Minmum acceptable probability of detecting an
out of control error condition.
4.Maximum acceptable probability of false
rejection.
*Main aim is to Maximize probability to detect
an out of control condition for measurement
procedure , while minimize probability for false
Q.C alerts.
13

Analysis of Control Materials
A stable control which mimics
patient’s sample is analyzed (DAY
TO DAY OR SET TO SET(

Need data set of at least 20 points,
obtained over a 30 day period

Calculate mean, standard
deviation, coefficient of variation;
determine target ranges

CLIA proficiency testing criteria for acceptable
analytical performance:

Objective

2.To identify the Quality control
charts and quality control roles

3.To identify the new rules of west
guard.
21

Monitoring QC Data
Develop Levey-Jennings chart.

Plot control values each run, make
decision regarding acceptability of run.

Monitor over time to evaluate the
precision and accuracy of repeated
measurements

Review charts at defined intervals, take
necessary action, and document

Levey-Jennings Chart
A graphical method for displaying
control results and evaluating whether
a procedure is in-control or out-of-
control

Control values are plotted versus time

Lines are drawn from point to point to
accent any trends, shifts, or random
excursions


The Levey-Jennings chart usually has the days of the month plotted on
the X-axis and the control observations plotted on the Y-axis.
On the right is the Gaussian or "bell-shaped" curve turned on its side to
show the correlation of the curve to the chart (ie, fewer data points
should appear on the upper and lower extremities of the chart, since the
"bell" is thinner farther from the mean).
By observing the data plotted in the L-J chart, we can determine if test
results are in control and accurate, or if test results are not in control
and consequently unacceptable. 24
.

Calculate the Mean and Standard Deviation;
Record the Mean and +/- 1,2 and 3 SD Control
Limits
3SD+115
2SD+ 110
1SD+ 105
Mean 100
1SD- 95
2SD- 90
3SD- 85
80
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Day

Levey-Jennings Chart -
Record Time on X-Axis and the Control Values on Y-
Axis
115
110
Control Values (e.g. mg/dL)

105
100
95
90
85
80
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

(Time (e.g. day, date, run number

Plot Control Values for Each Run

115
110
Control Values (e.g. mg/dL)

105
100
95
90
85
80
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

(Time (e.g. day, date, run number

Record and Evaluate the Control Values

3SD+ 115
2SD+ 110

1SD+ 105

Mean 100
95
1SD-
2SD- 90

3SD- 85

80 Day
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Look for
assignable
In control Out of control ! cause !

UCL Problem
Natural corrected
6σ Variation
Target
= Mean
3σ
LCL

Time
Samples Natural variation

“Allows determination of whether
an analytical run is “in-control” or
“out-of-control”

Westgard Rules are a multi role QC
procedure

1-West-gard rules: (Regular twice entry for Q.C)
3s, 1 2s, 2 2s , R 4s, 4 1s, 10x (& modifications 1
) 8x, 12x

Recent west-gard rules, fit better and are easier-2
to apply in situations where 3 different control
:materials are being analyzed
2of3 2s, 3 1s, 6x & 9x
A related control rule that is sometimes used-3
":looks for a "trend
7T

31

Westgard Rules are a multirule QC procedure

13s refers to a control rule that is commonly used
. with a Levey Jennings chart
A run is rejected when a single control
measurement exceeds the mean plus 3s or the
.mean minus 3s control limit

32

12s refers to the control rule that is commonly used with a
Levey-Jennings chart single control measurement exceeds
. the mean plus 2s or the mean minus 2s control limit
This rule is used as a warning rule to trigger careful
inspection of the control data by the following rejection rules .

33

22s - reject when 2 consecutive control
measurements exceed the same mean plus 2s
. or the same mean minus 2s control limit

34

R4s - reject when 1 control measurement in a group exceeds the
. mean plus 2s and another exceeds the mean minus 2s

35

measurements exceed the same mean plus 1s
. or the same mean minus 1s control limit

36

10x - reject when 10 consecutive control measurements fall
. on one side of the mean

:some modifications
8x - reject when 8 consecutive control measurements fall on
one side of the mean
12x - reject when 12 consecutive control measurements fall
. on one side of the mean

37

In situations where 3 different control materials are
being analyzed, some other control rules fit better and
:are easier to apply, such as
2of32s - reject when 2 out of 3 control measurements
exceed the same mean plus 2s or mean minus 2s control
limit

;

38

measurements exceed the same
mean plus 1s or mean minus 1s
.control limit

39

some modification:
6x - reject when 6 consecutive control
measurements fall on one side of the
mean.

40

A related control rule that is sometimes used,
looks for a "trend" where several control
measurements in a row are increasing or
decreasing
7T - reject when seven control measurements
trend in the same direction, i.e., get progressively
higher or progressively lower.
there are two types of errors, random and
systematic
the multirule combines the use of two types of
rules to help detect those two types of errors.

41

Corrective action

1- Determine the type of error occurring on
the basis of the rule violated.

2-Refer to trouble-shooting guides to identify
possible causes for the type of error indicated
by the control rule that was violated.

42

There are two types of errors, random and systematic
the multi rule combines the use of two types of rules to help
detect those two types of errors:

Type of Error Control rule that detects it

Random error 13s, R4s

Systematic error 2s, 4 1s, 2of3 2s, 3 1s, 6x, 8x, 9x, 10x, 2
12x, cusum

43

Correct the problem, then analyze control- 3
.samples again to assess control status
4- Repeat or verify the results on the patient
samples once the method has been demonstrated
to be in-control.
5- Consult a supervisor for any decision to report
patient results when a run is out-of-control.
48

OBJECTIVE

Overview of the CLSI guide lines
.C24

49

?Who is CLSI

Clinical and Laboratory Standards Institute
ANSI-accredited, global, nonprofit standards•
development organization
CLSI has over 2,000 members – organizations such•
as IVD
manufacturers, hospital laboratories, reference
,laboratories, universities
professional associations, and government agencies

50

CLSI –C24:Q.C planning process

Define Quality requirement inn the form of.1
.Allowable total error
.Select suitable Q.C material.2
Obtain estimates of methods of impersion and bias.3
.Identify traditional control rules.4
Predict performance in terms of probabilities for.5
rejection (including false rejection),through the
.available charts/graphs
Set goals for Q.C performance as probability of error.6
detection of 90%,and a probability of false rejection
.of 5% chance
Detect critical systemic errors using suitable.7
.graphical tools
51

Calculating Sigma Level of critical
systemic error

=Critical systemic error
total allowable error - Bias] )
%[mean)/Impercision

=SIGMA-METRIC
Critical systemic error + 1.65

52

CLSI EP23 Guideline

Laboratory Quality Control Based on Risk
Management—Proposed Guideline

guidance to enable labs to develop effective, cost-efficient
:QC protocols to
Reduce negative impact of test system’s-
.limitations
Monitor immediate and extended test-
.performance

53

For each risk, a mitigation strategy is found that will
.reduce the residual risk to an acceptable level

Sum of all QC elements (manufacturer provided and
laboratory added) becomes the laboratory’s QC plan
.specific to this device and the laboratory environment

56

CLSI EP23 Guideline

Doesn’t replace surrogate QC, but
incorporates surrogate QC to
address the potential for certain
risks

Utilizes a risk management
approach to developing a
.customized QC plan

Provides a scientific basis for
justifying QC strategies (useful for
(lab inspectors
57

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