RODRI CC2 Flashcards
system of ensuring accuracy and precision in the laboratory buy including quality control reagents in every series of measurements
Quality control
it is a process of ensuring that analytical results are correct by testing known samples that resemble patient samples
Quality control
process of monitoring the charactersitics of analytical processes, detects analytical errors, prevent reporting of inaccurate patient test results
Quality control
one component of the quality assurance system, and a part of performance monitoring that occurs after a test has been established
Quality control
ability of an analytical method to measure the smallest concentration of the analyte of interest
Sensitivity
ability of an analytical method to measure only the analyte of interest
Specificity
nearness or closeness of the assayed value to the true or target value
Accuracy
accuracy is estimated using 3 types of studies:
Recovery
Interference
Sample comparison
determines how much of the analyte can be identified in the sample
Recovery study
determines id specific compounds affect the laboratory tests like hemolysis, turbidity, icteric
Interference
used to assess presence of error [inaccuracy] in actual patient sample
Accuracy
ability of an analytical method to give repeated results on the same sample that agree with one another
Sample comparison
ability of an analytical method to give repeated results on the same sample that agree with one another
Precision or reproducibility
degree by which method is easily repeated
practicability
ability of analytical method to maintain accuracy and precision over an extended period of time during which equipment, rgts, and personnel may change
Reliability
ability of the analytical method to detect the proportion of individuals w/ the disease
diagnostic sensitivity
indicates the abilioty of the test to generate more true-positive results and few false-negative
Diagnostic sensitivity
Diagnostic sensitivity formula
Sensitivity= 100 x diseased individuals w/ positive test/ total # of individuals W/ TEST
ability of the method to detect true-negatives w/ very few false-positives.
diagnostic specificit
Diagnostic specificity formula
Sensitivity= 100 x diseased individuals w/ NEGATIVE test/ total # of individuals W/O DISEASE
2 Kinds of Quality Control
Intralab QC
Interlab QC
involves analyses of control samples together w/ the px samples
Intralab QC
detects changes in performance bet. present operation & stable operation
used to determine state-of-the-art interlaboratory performance
Intralab QC
interlab QC
important in the daily monitoring of accuracy and precision of ana. methods
important in maintaining long-term accuracy of the analytical methods
Intralab QC
Interlab QC
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
gold standard for clinical laboratory external QC testing
College of American Pathologists [CAP] Proficiency Program
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
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
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
Some proficiency tests are [quantitative or qualitative] however for chemistry, it should be [quantitative or qualitative]
qualitative
quantitative
If there is no available proficiency testing program for a certain analyte, it is required to implement a ______________
non-proficiency test scheme
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
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
The ultimate goal of ______ is to ensure our clinicians that patients results are accurate.
Proficiency testing
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
What are the three objectives of a Quality control?
- To check the stability of the machine
- To check the quality of reagents
- To check technical [operator] errors
The accuracy of any assay depends on the ______ how they are originally constituted and how they remain stable overtime
Control solutions
General chemistry assays used [2/3], levels of control solutions, while immunoassays used [2/3] levels
[2] and [3]
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
For highly precised assays (with less than [1%/10%] such as blood gases, analysis for ____ days is adequate
1%
5 days
Thee are expected values represented by intervals of acceptable values with upper and lower limits
Control limits
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
The ideal control limit is between _____
+/-2SD
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
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
Characteristics of an Ideal QC Material:
- Resembles human sample.
- Inexpensive and stable for long periods .
- No communicable diseases.
- No matrix effects/known matrix effects.
- With known analyte concentrations (assayed control).
- Convenient packaging for easy dispensing and storage.
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
Human control materials are preferred but because of limited sources and biohazard considerations,
______ control materials are used.
Bovine