Quality Flashcards
what authority is responsible for the clinical side
CQC - the care quality commission
analytical side of quality
UKAS and ISO15189
Internal quality control
used in real time to monitor performance of an assay. result should be in expected boundaries.
External quality assurance (EQA)
retrospective analysis of performance of an assay in comparison to other users
IQC material
generally bought commercially
can contain 1/multiple analytes
analytical results monitored by using a computer programme
EQC material
obtained by signing up to an EQA scheme
all assays should be subject to EQA- 15189- if not available then sample exchange scheme
choosing IQC material
matrix
3rd party (at least 1 QC not made by the manufacturer)
cost
levels available - min 2 normal and high
range of analytes - able to QC multiple assays
stability
where should target values be determined?
in house
frequency of IQC
depends on frequency of analysis
batch analysis IQC at beginning and end (if large number of samples then middle)
continuous flow analysis requires IQC throughout the day
guarantee accuracy of results
between acceptable IQC results
what is the target value
mean +/- 2 standard deviations
how do you know target value?
need to run up IQC
assayed IQC material is provided with target values
assay should be able to perform in a much more reproducible form within controlled conditions of your lab
new IQC material requires mean to be determined
SD should be checked but not changed between QC lots
is IQC in?
- Common practice is to accept IQC values within + 2SD of the mean and report patient results
- If IQC is >+ 2SD but <+ 3SD, Warning sign – assess the situation
- If IQC >+ 3SD, reject the run
- Practice varies between labs
systematic erros
see a shift / trend
causes of systematic errors
incorrectly assigned calibrator
calibration lot changes
reagent lot changes
light source deterioration
reagent/calibrator deterioration
