Quality Control Flashcards
detects errors; recognizes and minimizes Analytical Error
Quality control
Quality assurance
prevents error
Quality Management Systems
systematic actions necessary to provide confidence that lab services will satisfy medical needs for patient care
Clinical Chemistry Training
- quantitative: report [analyte] (units)
- semi-quantitative: report grade of [analyte]; 0/absent, 1+, 2+…
- qualitative: report presence: (pos)/absence (neg)
Internal QC
- regular statistical sampling to assess performance of lab measuring systems
- used to determine the acceptability (validity) of measurement procedure results
- known positive controls (analyte present within expected levels)
- known negative controls (analyte is not present at detectable levels)
Batch measurement procedure
QC sample results must be completed before patient samples can be reported
- per each batch
Continuous measurement procedure
patient samples are reported during the interval between QC measurements ; less frequent than batch
What is ‘error’ in lab analysis?
- measurement is not accurate
- measurements is not reproducible
Characteristics of Quality Control Samples (7)
- same matrix as the sample to be tested
- inexpensive
- ready to use
- stable for long periods
- sample directly
- assayable by independent methods
- readily available
Establishing the control range
- measure analyte of interest in control sample at least 40 times under a variety of conditions
=> different days, times of day, technologists, etc. - calculate mean, mean +/- 1sd, mean +/- 2sd, mean +/- 3sd
- Levey-Jennings Chart:
=> y-axis: mean +/- 1sd, mean +/- 2sd, mean +/- 3sd
=> x-axis: month & days of the month
how close the measured value agrees with the ‘true’ value
accuracy
reproducibility of a measured value
precision
pre-analytical phase
test request
specimen collection
specimen transport to lab
receipt of specimens
analytical phase
perform test
validate and interpret results
specimen management
post-analytical phase
report results
record keeping
