RODRI CC2 Flashcards
(122 cards)
1
Q
system of ensuring accuracy and precision in the laboratory buy including quality control reagents in every series of measurements
A
Quality control
2
Q
it is a process of ensuring that analytical results are correct by testing known samples that resemble patient samples
A
Quality control
3
Q
process of monitoring the charactersitics of analytical processes, detects analytical errors, prevent reporting of inaccurate patient test results
A
Quality control
4
Q
one component of the quality assurance system, and a part of performance monitoring that occurs after a test has been established
A
Quality control
5
Q
ability of an analytical method to measure the smallest concentration of the analyte of interest
A
Sensitivity
6
Q
ability of an analytical method to measure only the analyte of interest
A
Specificity
7
Q
nearness or closeness of the assayed value to the true or target value
A
Accuracy
8
Q
accuracy is estimated using 3 types of studies:
A
Recovery
Interference
Sample comparison
9
Q
determines how much of the analyte can be identified in the sample
A
Recovery study
10
Q
determines id specific compounds affect the laboratory tests like hemolysis, turbidity, icteric
A
Interference
11
Q
used to assess presence of error [inaccuracy] in actual patient sample
A
Accuracy
12
Q
ability of an analytical method to give repeated results on the same sample that agree with one another
A
Sample comparison
13
Q
ability of an analytical method to give repeated results on the same sample that agree with one another
A
Precision or reproducibility
14
Q
degree by which method is easily repeated
A
practicability
15
Q
ability of analytical method to maintain accuracy and precision over an extended period of time during which equipment, rgts, and personnel may change
A
Reliability
16
Q
ability of the analytical method to detect the proportion of individuals w/ the disease
A
diagnostic sensitivity
17
Q
indicates the abilioty of the test to generate more true-positive results and few false-negative
A
Diagnostic sensitivity
18
Q
Diagnostic sensitivity formula
A
Sensitivity= 100 x diseased individuals w/ positive test/ total # of individuals W/ TEST
19
Q
ability of the method to detect true-negatives w/ very few false-positives.
A
diagnostic specificit
20
Q
Diagnostic specificity formula
A
Sensitivity= 100 x diseased individuals w/ NEGATIVE test/ total # of individuals W/O DISEASE
21
Q
2 Kinds of Quality Control
A
Intralab QC
Interlab QC
22
Q
involves analyses of control samples together w/ the px samples
A
Intralab QC
23
Q
detects changes in performance bet. present operation & stable operation
used to determine state-of-the-art interlaboratory performance
A
Intralab QC
interlab QC
24
Q
important in the daily monitoring of accuracy and precision of ana. methods
important in maintaining long-term accuracy of the analytical methods
A
Intralab QC
Interlab QC
25
detects both random and systematic errors in a
[1week cycle/daily basis]
allows ID of analytical errors within [1week cycle/daily basis]
Inralab QC
daily basis
1wk cycle
26
gold standard for clinical laboratory external QC testing
College of American Pathologists [CAP] Proficiency Program
27
Which of the statements are true?
What makes the other statement false?
A series of unknown samples are sent to the laboratory from the reference laboratory or authorized program provider
Unknown samples must be tested by the laboratorians who regularly perform analysis of a patient specimen using the different reagents and equipment for actual patient specimens
A series of unknown samples are sent to the laboratory from the reference laboratory or authorized program provider
different = same
28
Which of the statements are false? What makes them false?
Analysis of the unknown samples should not be completed within the usual time as for the routine samples
Unknown samples should be treated like a reference specimen to determine the true essence of accuracy
should be completed
reference= unknown
29
Results of the proficiency testing [must be/must not be] shared with other laboratories during the testing period. Comparison studies can be made [when? ] to identify areas for improvement
must not be shared
after the testing cycle
30
Some proficiency tests are [quantitative or qualitative] however for chemistry, it should be [quantitative or qualitative]
qualitative
quantitative
31
If there is no available proficiency testing program for a certain analyte, it is required to implement a ______________
non-proficiency test scheme
32
in external WC, difference of greater than ___SD in the results indicates that a laboratory is not agreement w/ the rest of the laboratories included in the program
2
33
TRUE OR FALSE
If in case of clinical laboratory failed to identify or resolve an error or discrepancy in the process, the facility is at risk of continuous operation and may be recommended for closure.
True
34
The ultimate goal of ______ is to ensure our clinicians that patients results are accurate.
Proficiency testing
35
Modified T/F
Proficiency testing allows each laboratory to compare and evaluate test results or outcomes with those laboratories that use the same methods
Data obtained from the proficiency testing can be used to continuously improve test performance, and also serve as a troubleshooting guide when investigating error.
Both are true
36
What are the three objectives of a Quality control?
1. To check the stability of the machine
2. To check the quality of reagents
3. To check technical [operator] errors
37
The accuracy of any assay depends on the ______ how they are originally constituted and how they remain stable overtime
Control solutions
38
General chemistry assays used [2/3], levels of control solutions, while immunoassays used [2/3] levels
[2] and [3]
39
To establish statistical quality control on a new instrument or new lot number of control materials, the different levels of control material must be analyzed for ___ days.
20 days
40
For highly precised assays (with less than [1%/10%] such as blood gases, analysis for ____ days is adequate
1%
5 days
41
Thee are expected values represented by intervals of acceptable values with upper and lower limits
Control limits
42
Modified T/F
If the expected values are within the desired control limits. The clinicians are assured that the test results are accurate and precise
Control limits are calculated form the mean and variance
True
Variance = standard deviation
43
The ideal control limit is between _____
+/-2SD
44
Modified T/F
Use of a double lot for an extended period allows reliable interpretative criteria to be established which will permit efficient identification of and assay problem
When charging to a new lot number, laboratorians use the newly calculated [SD/mean] value as the target [SD/mean] but retain the [SD/mean] value, but when more data are obtained, all values should be
averaged to get the best estimates of the mean and SD.
Double = single
Mean - Mean - SD
45
Modified T/F
Determination of the mean and SD for the assayed controls is also advisable because this process
improves the performance characteristics of statistical control procedures.
Asseyed = unassayed
46
Characteristics of an Ideal QC Material:
1. Resembles human sample.
2. Inexpensive and stable for long periods .
3. No communicable diseases.
4. No matrix effects/known matrix effects.
5. With known analyte concentrations (assayed control).
6. Convenient packaging for easy dispensing and storage.
47
Quality control materials should resemble human sample and be available for a [minimum/maximum] of one year (same lot number) - different lot numbers of the [same/different] material have different concentrations
which requires new estimates of the mean and standard deviation.
Minimum
Same
48
Human control materials are preferred but because of limited sources and biohazard considerations,
______ control materials are used.
Bovine
49
Bovine-based QC material [is/is not] the choice for immunochemistry, dye-binding and certain bilirubin
assays.
Is not
50
Modified T/F
QC materials should be the same matrix as the specimens being tested, for example, measurement
of glucose in serum should have control solutions that are prepared from serum.
Matrix effects are results of improper product manufacturing, use of unpurified human and
nonhuman analyte additives and altered protein components.
Both are true
51
Modified T/F
Control materials can be purchased with and without assayed values.
Assayed controls are more expensive but can be used as internal checks for accuracy.
and = or
internal = external
52
Modified T/F
Reconstitution of lyophilized control materials must be properly done to avoid incorrect control
values.
Stabilized frozen controls do not require reconstitution but may have different characterizations
same to actual patient specimens.
True
Same = compare
53
The test method must be compared always with a method of acceptable accuracy such as the
__________ (gold standard).
standard reference method
54
Modified T/F
It is recommended by Westgard et al and Clinical Laboratory Improvement Amendments (CLIA)
that 40 to 100 samples be run by each method in duplicate on the same day over 8 to 30 days
ideally within 4 hours, to determine its accuracy and precision.
If only 40 samples will be measured, daily analysis in duplicate of 2 to 5 specimens should be
followed for at least 7 days.
30 days = 20 days
7 days = 8 days
55
_________ analyses of each sample by each method (test method and reference method) are
recommended, with the duplicate samples analyzed in different runs and in different order of
analysis on the two runs (should be performed within 4 hours).
Duplicate
56
The rationale for performing repeated assays is to _________ that affect precision.
detect random errors
57
After analyses, samples with wide difference should be ______ to rule out technical errors as
the source of ______.
Repeated
Variation
58
The most important characteristic of method evaluation is to determine if the total error (random and systematic error) is [more/less] than the allowable error (Ea).
Less
59
Are errors encountered in the collection,preparation and measurementof samples,
including transcription and releasing of laboratory results.
Variations
60
Basis for varying differences between repeated measurements
A. Systematic error
B. Random error
C. Clerical error
D. Constant error
B. Random error
61
It is present in al measurements: it is due to chance.
A. Systematic error
B. Constant error
C. Clerical error
D. Random error
D. Random error
62
Type of error which varies from sample to sample
Random error
63
It is due to instrument, operator and environmental conditions (variations in techniques) such as
pipetting error, mislabeling of samples, temperature fluctuation, and improper mixing of sample
and reagent.
Random error
64
Modified T/F
Systematic Error is an error that influences observations consistently in two direction (constant difference).
Systematic Error is detected as neither positive nor negative bias - often related to calibration problems,
deterioration of reagents and control materials, improperly made standard solutions,
contaminated solutions, unstable and inadequate reagent blanks, leaky ion selective electrode
(¡SE), failing instrumentation and poorly written procedures.
Two = one
Neither nor = Either or
65
It is a measure of the agreement between the measured quantity and the true value.
A. Systematic error
B. Constant error
C. Clerical error
D. Random error
A. Systematic error
66
Modified T/F
Constant error refers to a difference between the target value and the assayed value while percent error results in greater deviation from the target value due to higher sample concentration.
Percent error exists when there is a continual difference between the comparative method and the
test method regardless or the concentration while constant error it exists when the difference between the test method and the comparative method
values is proportional to the analyte concentration.
True
Percent error = constant error
Constant error = Percent error
67
Modified T/F
Systematic error is the highest frequency of clerical errors occurs with the use of handwritten labels and
request forms.
Proportional error is independent of sample concentration.
Systematic error = clerical error
Proportional error = constant error
68
Enumerate the indicators of analytic performance:
1. Internal QC
2. Proficiency testing
3. Accreditation
4. Quality
5. Assurance monitoring and laboratory utilization
69
The first step in method evaluation
The precision study which estimates the random error.
70
Modified T/F
To study imprecision or random error, 2 control solutions are run [once/twice] a day in a 10- to 20-day
period - by testing multiple samples on different days, a better assessment of random error over time is achieved.
The total imprecision analysis is the most accurate measure of performance that would affect
the laboratory values a clinician might observe and reflects differences such as in the work of
technologists, pipetting and temperature fluctuations of the analyzers.
Twice
True
71
Determine if it’s pre, ana, or post error
1. Incorrect anticoagulant to blood ratio (short draw)
2. Equipment/instrument malfunction
3. Incomplete centrifugation
4. Incorrect sample and reagent volume
5. Long turnaround time
6. Mishandled specimen
1. Pre
2. Ana
3. Pre
4. Pre
5. Post
6. Pre
72
Refers to all the activities that take place before testing, such as test ordering and
sample collection.
Preanalysis
73
Modified T/F
The most frequent analytical errors include improperly filling the sample tube, placing
specimens in the wrong containers or preservatives, and selecting the incorrect test.
The post analysis stage consists of the laboratory activities that actually produce a result, such as
running a sample on an automated analyzer. Postanalysis comprises patient reporting and result
Interpretation.
Analytical = Pre
Post analysis = analysis
74
Modified T/F
The length of time elapsed between drawing and the separation of serum or plasma from the
cells can be a factor in analytical testing.
Laboratory personnel were responsible for 29% of the errors with regard to laboratory
results.
True
Laboratory = Non laboratory
75
Modified T/F
Online computer input is the most error-free means of requesting laboratory tests.
Most laboratory errors occur in the preanalytic and postanalytic stages.
Both are true
76
What study is this?
Error rates were reported to range from 0.05% to 0.61%, and the distribution of
errors among the testing stages was similar, with most (32%-75%) occurring in the preanalytic
stage and far fewer (13%-32%) in the analytic stage
(Bonini et al, 2002 cited in McPherson and
Pincus 2017).
77
Modified T/F
Allowable error is determined for each test method and is expressed either in measurement units of the
analyte (mmol/L) or percentages.
Allowable error is based on the quality of error that will negatively affect clinical decisions.
True
Quality = quantity
78
Modified T/F
The total error (random, proportional, constant and systematic error) must be less than the Ea or
fixed limits for a method to be considered acceptable.
If the total error is greater than Ea, corrections must be made to reduce the error or the method
be rejected.
Both are true
79
STATISTICS
______ a measure of central tendency.
______ measure of the dispersion of values from the mean.
______ is called the standard deviation squared
______ percentile expression of the mean; an index of precision
Mean
Standard Dev
Variance
Coefficient of variation
80
The difference between T-test and F-test
F-test is used to determine whether there is a statistically significant difference between the
standard deviations of two groups of data while T-test is the difference between the means of two groups of data
81
Terminologies:
_____ midpoint of a distribution
_____ used to compare the means or standard deviations of two groups of data
_____ the simplest expression of spread or distribution;
_____ the difference between the value of a data point and the mean
value divided by the group's SD
Median
Inferential statistics
Range
SD Index
82
Modified T/F
Statistical analyses are used to determine the types and quantity of error that a method has, and
to decide whether the test is still valid or acceptable to make clinical decisions.
Parametric tests: t-test and analysis of variance (ANOVA)
Acceptable = unacceptable
True
83
3 measures of spread or distribution
CV, SD and range
84
______ describes the distribution of all values around the mean.
______ and ______ represent the average distance from the center of the data (mean) and every value
in the data set.
______ allows a laboratorian to compare SDs with different units.
SD
SD and variance
CV
85
Modified T/F
The CV of anälyzers described as having reproducible test results can be lower than 1%.
Degree of freedom (n-1) indicates the number of quantities free to vary.
Both are true
86
Modified T/F
ANOVA is used to analyze precision data to give estimates of the within-in run, between-run and
total imprecision.
> Method evaluation and statistical analysis are essential, but not sufficient to decide if a test is valid.
Both are true
87
The acceptable range is __% confidence limit which is equivalent to ‡
95%
88
Modified T/F
QUALITY CONTROL CHART is used to observe values of control materials over time to determine reliability of the
analytical method.
QUALITY CONTROL CHART is utilized to observe and detect analytic errors such as accuracy and imprecision.
True
Accuracy = inaccuracy
89
Determine if its [A. Gaussian Curve B. Cumulative sum graph C. Youden/Twin plot D. Shewhart Levey]
1. It is obtained by plotting the values from multiple analyses of a sample.
2. It is a graphic representation of the acceptable limits of variation in the results of an analytical
method.
3. The points falling from a center but on the 45° line suggest a proportional error, and points
falling fror the center but not on the 45° line suggest a constant error.
4. It is very sensitive to small, persistent errors that commonly occur in the modern, low
calibration-frequencyanalyzer.
5. it focuses on the distribution of errors from the analytical method rather than the values from a
healthy or patient population.
6. It calculates the difference between QC results and the target means.
7. It is the most widely used QC chart in the clinical laboratory.
8. it displays the results of the analyses by plotting the mean values for one specimen on the
ordinate (y-axis) and the other specimen on the abscissa (x-axis).
1. A 7. D
2. D. 8. C
3. C
4. B
5. A
6. B
90
Determine if its [A. Gaussian Curve B. Cumulative sum graph C. Youden/Twin plot D. Shewhart Levey]
1. This plot will give the earliest indication of systematic errors (trend) and can be used with the 13s
rule.
2. It occurs when the data set can be accurately described by the SD and the mean.
3. It easily identifies random and systematic errors.
4. It is used to compare results obtained on a high and low control serum from different
laboratories.
5. It is a population probability distribution that is symmetric about the mean.
It occurs when data elements are centered around the mean with most elements close to the
mean.
6. It allows the laboratorians to apply multiple rules without the aid of a computer.
7. Common method: V-mask.
It identifies consistent bias problems; it requires computer implementation.
8. The total area under the curve is 1.0 or 100%.
1. B
2. A
3. D
4. C
5. A
6. D
7. B
8. A
91
Determine if its [A. Trend B. Shift C. Outliers]
1. Shift in the reference range is due to transient instrument differences.
2. Main cause: Deterioration of reagents
3. It is formed by control values that either increase or decrease for six consecutive days.
4. These are caused by random or systematic errors.
5. It is formed by control values that distribute themselves on one side or either side of the mean
for six consecutive days.
6. These are control values that are far from the main set of values.
7. Main cause; Improper calibration of the instrument
8. These are highly deviating values.
1. B
2. A
3. A
4. C
5. B
6. C
7. B
8. C
92
Westgard Control Chart
It recognizes that the use of ______ upper and lower control limits is not enough to identify
analytical problems.
In Westgard, error detection rates can _____ without increasing the false rejection rate.
Westgard used the term _______ to indicate if the analytical process is out of control.
Simple
Increase
Control rule
93
It is observed when one control result exceeds the mean +- 3SD; due to random error.
1[3s]
94
The last four (or any four) consecutive control results exceed either mean + - 1SD• due to systematic error.
4[1s]
95
It is used as a rejection or warning rule when one control result exceeds the mean + - 2SD: for screening purpose
1[2]s
96
It is observed when the last 2 control results or 2 results from the same run exceed either the mean + - 2D: due to svstematic error
2[2s]
97
The range or difference between the highest and lowest control result within an analytical run exceeds 4s; it is due to systematc error.
R[4s]
98
We need to reject an analytical run when
8 consecutive control measurements fall on one side of the mean
8x
99
We need to reject an analvtical run when 6 consecutive control measurements fall on one side of the mean
6x
100
We need to reject an anavtical run when
seven control measurements "trend" in the same direction, i.e., get progressively higher or progressively lower
7[T]
101
reject when 12 consecutive control
measurements fall on one side of the mean
12x
102
It is observed when 10 consecutive results are on The Same
side of the mean: due to systematic error.
10x
103
We need to reject an analytical run when 2 out of 3 control measurements exceed the mean plus 2s or mean minus 2s control limit
2of3[2s]
104
We need to reject an analvucal run when
9 consecutive control measurements fall on one side of the mean.
9x
105
We need to reject an analytical run when 3 consecutive control measurements exceed the same mean plus 1s or mean minus 1s control limit.
3[1s]
106
It is the concentration range over which the measured concentration is equal to the actual concentration without modification of the method.
Linear Range/Dynamic Range
107
It is a set of control and patient specimens assayed, evaluated and reported together.
Analytical run
108
It includes effective test request forms, clear instruction for patient preparation and specimen handling, appropriate turn around time for specimen processing, testing and result reporting,
appropriate reference ranges and intelligent result reports.
Quality Patient Care
109
It is the probability that a negative test indicates absence of disease. It is the proportion of persons with a negative test who are truly without disease.
Negative predictive value
110
It is the probability that a positive test indicates disease; it is the proportion of persons with a positive test who truly have the disease.
Positive predictive value
111
Physiologic Limit
Is sometimes referred to as ______.
It helps ______ sample contamination or dilution, inadequate sample volume, inadequate reagent volumes, sudden major problems with the method, or incorrect recording or transmission of the result.
absurd value
Detect
112
These are used to measure systematic errors or inaccuracy caused by substances other than the
analyte.
Interferences: hemoglobin, lipids, bilirubin, anticoagulants and preservatives
Interference experiments
113
It is a type of analytical testing performed outside the confines of the central laboratory, usually by nonlaboratorian personnel (nurses, respiratory therapists, etc).
Most commonly used POCT: use of portable whole blood glucose meters for the management of patients with diabetes mellitus.
Point Of Care Testing (POCT)/Decentralized Testing
114
It can be envisioned as a tripod with program development, assessment and monitoring, and quality improvement forming the three legs.
Is a systematic action necessary to provide adequate confidence that laboratory services will satisfy the given medical needs for patient care.
Quality Assurance (QA)
115
Primary Goal of QA
To deliver quality services and products to customers.
116
It shows whether a method measures all the analytes or only part of it.
It estimates inaccuracy or systematic error.
Recovery experiment
117
Delta check
It is the [less/most] commonly used patient based QC technique.
It requires computerization of test data so that [current/past] results can be compared with past results.
It is the difference between two consecutive measurements of the [same/different] analytes on the same
individual.
Most
Current
Same
118
Modified T/F
Predictive value depends on sensitivity, specificity, and prevalence of the disease being test.
Predictive value is when a test cutoff changes, its accuracy (sensitivity/specficity) and predictive value also change.
Both are true
119
Bayes' theorem (predictive value theory) describes the relationship between posttest and pretest probability of disease or no disease based on the sensitivity and specificity of the test.
Predictive value
120
Modified true or false
Reference Limit/Reference Interval/Reference Value
It is a value obtained by observation or measurement of a particular type of quantity on a reference individual.
It is a pair of medical decision points that extend the limits of test results for a certain healthy population.
Both are true
121
Modified T/F
Reference Limit/Reference Interval/Reference Value
It is the range of values into which 90% of nondiseased individuals will fall - this definition implies that 10% of nondiseased individuals can have laboratory results outside the reference
range.
It is the usual values for a healthy population that represents 90% central tendency.
90% = 95%
10% = 5%
90% = 95%
122
Modified T/F
Reference Limit/Reference Interval/Reference Value
It is usually established by the manufacturers of reagents or group of experts
It is mostly determined using nonparametric statistics (CLS| recommended method).
Both are true
