QUALITY ASSURANCE/CONTROL Flashcards
Overall program that ensures that the final
results reported by the laboratory are correct
Quality Assurance
➔ AKA External Quality Control
➔ Involves proficiency testing
programs
➔ Ex.: National External Quality
Assessment Scheme (NEQAS)
Interlab
➔ System of ensuring accuracy and precision in the lab
➔ Process of ensuring that analytical results are correct
➔ QC samples are measured periodically in the same manner as clinical samples
Quality Control
➔ AKA Internal Quality Control
➔ Analyses of control samples
together with patient specimens
➔ Important in daily monitoring
Intralab
Reagent without any analyte added
Reagent Blank
➔ Most specific analytical solution
➔ Value will tell the conc. of the
unknown
➔ Only one analyte
Standard
➔ Value will determine accuracy and
precision
➔ Resembles patient sample
➔ Many analyte
Control
Indicating a person has the disease when, in fact, he or she does not
False positive
-Done on apparently healthy
individuals
-Not a basis for treatment
-Less accurate, less expensive
Screening Test
-Done on sick or ill individuals
-Basis for treatment
-More accurate, more expensive
Diagnostic Test
Refers to how well the test measures what it is
supposed to measure. It refers to the accuracy of the test, meaning how close the result is to its true value.
Validity
Indicating a person has the disease when, in fact, he or she does
True positive
(TP)
Refers to how well the test performs in use over time.
It refers to the precision of the test, meaning how close are the results of a test on repetition or how close the
values are from one another.
Reliability
Indicating a person has the disease when, in fact, he or she
does not
False positive
(FP)
Indicating a person does not have the disease when, in fact, he or she
does
False negative
(FN)
Ability of test to detect the smallest amount of
analyte
SENSITIVITY
Indicating a person does not have
the disease when, in fact, he or she
does not
True negative
(TN)
Ability of test to identify correctly those who
have the disease (a) from all individuals with
the disease (a+c)
Diagnostic Sensitivity
Ability of the test to identify correctly those
who do not have the disease (d) from all
individuals free from the disease (b+d)
Diagnostic Specificity
Diagnostic Sensitivity formula
TPTP + FN
Ability of test to detect substances without
interferences
SPECIFICITY
Diagnostic Specificity formula
TNTN + FP