B - CHAPTER IV: QUALITY CONTROL IN CLINICAL CHEMISTRY Flashcards

1
Q

– a degree to which a set of inherent characteristics fulfills requirements (ISO 9001:2008)

A

QUALITY

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2
Q
  • part of quality management focused on fulfilling quality requirements (ISO 9000:2000)
A

QUALITY CONTROL

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3
Q

• System of assuring the quality of total laboratory performance

A

QUALITY CONTROL

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4
Q

• Involves the periodic systematic surveillance of people, tools, methods and reagents

A

QUALITY CONTROL

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5
Q

– part of quality management focused on providing confidence that the quality requirements will be fulfilled (ISO 9000:2000)

A

QUALITY ASSURANCE

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6
Q
  • Set of activities or plan that aims to maintain the highest degree of excellence for the diagnosis & treatment of disease and maintenance of health
A

QUALITY ASSURANCE PROGRAM

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7
Q

AREAS of QUALITY CONTROL:

  1. All [?] are involved.
  2. The laboratory’s relation to other [?]
  3. Laboratory [?] should be collected in a manual to be revised at least once a year or when procedures are changed.
A

patients, laboratory personnel, laboratory equipment, and laboratory tests
hospital departments
policies and procedures

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8
Q

SYSTEM CONCEPTS of QUALITY CONTROL:

A
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9
Q

– establishes norms that must be met

A
  1. Quality Control Surveillance System (QCCS)
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10
Q

– established to offer education of why errors occur; provide a program to remedy defects

A
  1. Q.C. Corrective System
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11
Q

– established to prove that corrective measures have produced favorable results.

A
  1. Objective Q.C. Parameters
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12
Q

PROCEDURES in QUALITY ASSURANCE PROGRAM

A
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13
Q

A. CONTROL of PRE-ANALYTICAL VARIABLES FACTORS:

A
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14
Q

B. CONTROL OF ANALYTICAL VARIABLES MAIN FACTORS:

A
  1. Choice of analytical methodology
  2. Calibration procedures
  3. Proper documentation of analytical variables
  4. Proper labeling & use of reagents
  5. Preventive maintenance of analytical instruments
  6. Periodic calibration of pipetting devices
  7. Periodic checking of °T of refrigerator & heating units
  8. Periodic checking of procedure manuals
  9. Monitoring of technical competence
  10. Inventory of control materials
  11. Control assurance that safety measures are operational
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15
Q

C. CONTROL of POST-ANALYTICAL VARIABLES FACTORS:

A
  1. Verification of calculations of the final results
  2. Check test results for possible transcription errors
  3. Results should be easy to read & interpret
  4. Timeliness of reporting values to patient chart
  5. Procedures for informing physicians about results that require immediate attention
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16
Q

FACTORS Involved in QUALITY CONTROL

A
  1. STANDARD
  2. CONTROL MATERIAL
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17
Q

o A substance of known composition

A

STANDARD

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18
Q

o Its value is established by an analytical procedure different from that used in the clinical laboratory

A

STANDARD

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19
Q

o A substance which resembles the unknown specimen (patient’s sample)

A

CONTROL MATERIAL

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20
Q

o Analyzed daily together with the unknown

A

CONTROL MATERIAL

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21
Q

o The values obtained from the assays are used for the computation of the mean and the SD

A

CONTROL MATERIAL

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22
Q

Types of Control Material:

A

a. Commercial Control Sera
b. Pooled Sera

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23
Q
  • are collected daily in the laboratory and pooled for storage in the refrigerator
A

Excess non-hemolyzed sera without gross lipemia

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24
Q
  • When [?] are collected, centrifuge to remove gross contamination
A

1 – 2 liters

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25
Q
  • Filter and divide into aliquots of [?] each
A

5 mL

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26
Q
  • Stopper and store at
A

-20°C

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27
Q
  • [?] as needed and mix well before use
A

Thaw

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28
Q

ELEMENTS of QUALITY CONTROL:

A
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29
Q

– extent to w/c the measurement approximates the true value of the quantity being measured

A

ACCURACY

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30
Q

– a.k.a reproducibility; degree to w/c repeated results agree to each other

A

PRECISION

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31
Q

– ability of a method to detect a particular substance w/o the interference of some other substances present in the sample

A

SPECIFICITY

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32
Q

– ability of a method to detect even the smallest amount of that particular substance tested for

A

SENSITIVITY

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33
Q

– ability of a method to maintain its accuracy & precision over an extended period of time 6. PRACTICABILITY – degree to w/c the method is easily repeated

A

RELIABILITY

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34
Q

STATISTICAL CONCEPTS in QUALITY CONTROL

A
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35
Q

➢ A statement of the extent of random variation in any series of measurement

A

STANDARD DEVIATION

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36
Q

➢ A measure of the distribution of values around the mean

A

STANDARD DEVIATION

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37
Q

 Square of the standard deviation

A

VARIANCE (s2)

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38
Q

 Used to detect significant differences between groups of data

A

VARIANCE (s2)

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39
Q

 Determine contributions of various factors to the total variation

A

VARIANCE (s2)

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40
Q

 Percentile expression of the mean

A

COEFFICIENT OF VARIATION

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41
Q

 Measure of the relative magnitude of variability

A

COEFFICIENT OF VARIATION

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42
Q

QUALITY CONTROL Associated Activities:

A
  1. Assay of control samples
  2. Instrument maintenance
  3. Statistical Data Analysis
  4. Proficiency testing survey
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43
Q

ASPECTS which the laboratory should avoid or minimize:

A
  1. Analytical Bias
  2. Random Analytical Variability
    3.ERRORS
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44
Q

❖ Reported values do not fall along the line of slope when graphed

A

Analytical Bias

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45
Q

❖ Reported lab results do not correspond to the correct value

A

Analytical Bias

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46
Q

Types of Analytical Bias:

A

a) Proportional bias
b) Constant bias
c) Combined bias

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47
Q

Problem on Accuracy (Bias) =

A

Systematic Error

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48
Q

Refers to laboratory analyses that are subject to imprecision

A

Random Analytical Variability

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49
Q

Random Analytical Variability Types:

A

A. Proportional variability
B. Constant variability

50
Q

Problem on Precision (CV)

A

Random Error

51
Q

– can be systematic or personnel-related

A

ERRORS

52
Q

TYPES OF ERRORS:

A

A. RANDOM ERRORS
B. SYSTEMATIC ERRORS

53
Q

 Sources cannot be completely controlled or identified

A

RANDOM ERRORS

54
Q

 Increase the extent of variability of results

A

RANDOM ERRORS

55
Q
  1. Pipets & volumetric glassware w/ manufacturing variation; electronic & optical variations in instruments (e.g. spectrophotometers)
A

RANDOM ERROR

56
Q
  1. Variations in the cuvet
A

RANDOM ERROR

57
Q
  1. Variations in timing & °T control
A

RANDOM ERROR

58
Q
  1. Variations in light, evaporation & °T on serum sample
A

RANDOM ERROR

59
Q
  1. Interferences from other substances in the sample
A

RANDOM ERROR

60
Q

 Displace the mean value on one direction (may be up or down), but do NOT affect the overall variability as shown by the SD value

A

SYSTEMATIC ERRORS

61
Q
  1. Aging phenomena – decomposition of reagents during storage
A

SYSTEMATIC ERROR

62
Q
  1. Personal bias of the analyst
A

SYSTEMATIC ERROR

63
Q
  1. Laboratory bias
A

SYSTEMATIC ERROR

64
Q
  1. Inter- & intra-individual bias
A

SYSTEMATIC ERROR

65
Q
  1. Experimental errors or changes in the methods
A

SYSTEMATIC ERROR

66
Q
  • Series of values on the control chart that continue to increase or decrease for at least a period of six (6) consecutive days
A

TREND

67
Q

CAUSES of UPWARD TREND:

A

o Expired lamps/photocells
o Denatured standard
o Contamination of reagents

68
Q

CAUSES of DOWNWARD TREND:

A

o Standards that are too concentrated
o Contamination of reagent

69
Q
  • Values that distribute themselves on one side of the mean for at least six (6) consecutive days
A

SHIFT

70
Q

CAUSES of UPWARD SHIFT:

A

o Partial electrical failure in instrument
o New standard is over-diluted
o Denatured standard that has stabilized
o Improperly prepared reagent
o Inaccurate timer
o Deteriorated indicator
o Dirty glassware
o Overheating in °T-sensitive analysis

71
Q

CAUSES of DOWNWARD SHIFT:

A

o Increased concentration of standard & reagents
o Contaminated reagents
o Inaccurate timer
o Under-heating in analysis
o Contaminated glassware

72
Q

DIVISIONS of QUALITY CONTROL

A

 INTRALABORATORY / INTERNAL
 INTERLABORATORY / EXTERNAL

73
Q

 Q.C. procedures performed on a daily basis within individual laboratories

A

INTRALABORATORY / INTERNAL

74
Q

INTRALABORATORY / INTERNAL Monitoring is carried out using:

A

o Levey – Jennings Chart
o Westgard Multi-rule Chart
o CUSUM Technique

75
Q

 Performed on a less frequent basis (e.g. 3x a year) to compare performance b/w or among laboratories

A

INTERLABORATORY / EXTERNAL

76
Q

– graphical representations that display the control observation as a function or time

A

QUALITY CONTROL CHARTS

77
Q

 Control results are plotted on the Y-axis (ordinate) vs time on the X-axis (abscissa)

A

LEVEY – JENNINGS CHART

78
Q

IN-CONTROL:

A

 All control values are w/in ± 2SD
 One outlier in 20 determinations

79
Q

OUT-OF-CONTROL:

A

 Presence of two or more outliers
 Presence of a Trend
 Presence of a Shift

80
Q
  • a control value that goes beyond ±2SD
A

Outlier

81
Q

Causes of Outlier

A

o Contamination of a single specimen
o Faulty pipette
o Incorrect dilution of test

82
Q

 Uses a series of control rules for interpreting data

A

WESTGARD MULTIRULE CHART

83
Q

 False rejection is kept low

A

WESTGARD MULTIRULE CHART

84
Q

 Error detection is improved

A

WESTGARD MULTIRULE CHART

85
Q

 Analyse samples of the control material by the analytical method to be evaluated (at least 20 days)

A

WESTGARD MULTIRULE CHART

86
Q

One control observation exceeds ±2SD Warning

A

12S

87
Q

2 consecutive values exceed ±2SD

A

22S

88
Q

One value exceeds ±3SD

A

13S

89
Q

One value exceeds +2SD & the other value exceeds -2SD

A

R4S

90
Q

4 consecutive values exceed ±1SD

A

41S

91
Q

10 consecutive values fall on one side of the mean

A

10X

92
Q

 Hands-on process with the single mantra of “improvement”

A

SIX SIGMA

93
Q

SIX SIGMA Improved:

A

performance
quality
bottom line
customer satisfaction
employee satisfaction

94
Q

 The # of defects per million opportunities (DPMO) is measured

A

SIX SIGMA

95
Q

 Provides a display of the differences b/w the observed values & the expected mean

A

CUMULATIVE SUM (CUSUM) CHART

96
Q

 Obtain the CUSUM by adding the difference (value from the mean) to the CUSUM of the previous differences

A

CUMULATIVE SUM (CUSUM) CHART

97
Q

o Examine the slope of the CUSUM line

A

CUMULATIVE SUM (CUSUM) CHART

98
Q

o A steep slope suggests the presence of SE (Out of Control)

A

CUMULATIVE SUM (CUSUM) CHART

99
Q

– found in clin. Laboratories w/ microcomputer Q.C. programs

A

o DECISION LIMIT CUSUM

100
Q

 Laboratory’s observed mean for material A (Y-axis) compared to the observed mean for material B (X-axis)

A

YOUDEN PLOT / SCATTER DIAGRAM

101
Q

 Information about the nature of the SE can be obtained when two diff. control materials have been analyzed

A

YOUDEN PLOT / SCATTER DIAGRAM

102
Q

OTHER QUALITY CONTROL TOOLS

A
  1. CHECK SHEET
  2. PARETO CHART
  3. CAUSE & EFFECT DIAGRAM
  4. FLOW CHART
  5. HISTOGRAM
103
Q
  • Presents information in an efficient, graphical format
A

CHECK SHEET

104
Q
  • Accomplished with a simple listing of items
A

CHECK SHEET

105
Q
  • Used to identify factors that have the greatest cumulative effect on the system
A

PARETO CHART

106
Q
  • Ishikawa or Fish bone diagram
A

CAUSE & EFFECT DIAGRAM

107
Q
  • Used to associate multiple possible causes with a single effect
A

CAUSE & EFFECT DIAGRAM

108
Q
  • Primary branch
A

CAUSE & EFFECT DIAGRAM

109
Q
  • Major branches
A

CAUSE & EFFECT DIAGRAM

110
Q
  • Minor branches
A

CAUSE & EFFECT DIAGRAM

111
Q
  • Pictorial representations of a process
A

FLOW CHART

112
Q
  • Used in identifying where errors are likely to be found in the system
A

FLOW CHART

113
Q
  • Provides a simple, graphical view of accumulated data, including its dispersion & central tendency
A

HISTOGRAM

114
Q
  • Ease of construction
A

HISTOGRAM

115
Q
  1. Patient identification
A
116
Q
  1. Proper preparation of patient
A
117
Q
  1. Specimen collection, separation & processing
A
118
Q
  1. Choice of analytical methodology
A
119
Q
  1. Calibration procedures
A
120
Q
  1. Proper documentation of analytical variables
A
121
Q
  1. Proper labeling & use of reagents
A