BioRAD QC 1 (Complete Overview)

the statistical process used to monitor and evaluate the analytical process that produces patient results:

QC

used to evaluate whether the instrument is operating within pre-defined specifications, inferring that patient test results are reliable:

QC

used to express how far apart numerical values are from each other:

imprecision

provides the laboratory an estimate of test consistency at specific concentrations:

standard deviation

standard deviation and imprecision have a direct relationship (e.g., low SD, low imprecision OR high SD, high imprecision). true or false?

true

consistent or inconsistent: low SD, low imprecision?

consistent

consistent or inconsistent: high SD, high imprecision?

inconsistent

used to monitor on going day to day performance:

standard deviation

allows the laboratory professional to make easier comparisons of the overall precision:

CV

typically increases as the concentration of the analyte increases:

standard deviation

can be used when comparing instrument performance:

CV

commonly used for preparing a levey-jennings chart:

standard deviation

used to graph successive (run-to-run or day-to-day) quality control values:

LJ chart

created for each test and level of control:

LJ chart

first step of creating a levey-jennings chart is to calculate:

decision limits

approximately ____ of all QC values fall within ±1 standard deviation (1s) of the mean.

68%

approximately ____ of all QC values fall within ±2 standard deviation (2s) of the mean.

95.5%

about ____ of all data will be outside the ±2s limits when the analytical process is in control.

4.5%

approximately ____ of all QC values are found to be within ±3 standard deviations (3s) of the mean.

99.7%

as only ____ will fall outside the ±3s limits, any value outside of ±3s may be associated with a significant error condition.

0.3% (3 out of 1000 points)

the combination of patient and quality control specimens analyzed together is referred to as:

analytical run

should identify the name of the test, the instrument, units, the date the test is performed, the initials of the person performing the test, and the results for each level:

QC log

there should be room to enter corrective actions taken to resolve any situation which is identified as “out-of-control” or unacceptable and a place for documentation of supervisory review:

QC log

method and the assay temperature (usually included for enzymes) are optional to include in a ____.

QC log

once the QC results are entered into the QC Log, they should be plotted on the ____.

LJ chart

is evidenced by a change in the mean of the control values:

systematic error

the change in the mean may be gradual and demonstrated as a ____in control values:

trend

the change in the mean may be it may be abrupt and demonstrated as a ____ in control values

shift

indicates a gradual loss of reliability in the test system; often subtle:

trend

represent a sudden and dramatic positive or negative change in test system performance:

shift

in the absence of added analytical error, about ____ of all quality control results will fall between the 2s and 3s limits.

4.5%

warning rule that is violated when a single control observation is outside the ±2s limits:

1_2s

error associated with 1_2s:

random or systematic error

if no relationship can be found and no source of error can be identified, it must be assumed that a single control value outside the ±2s limits (1_2s) is an acceptable ____.

random error

using the 1_2s rule as a rejection rule will generate ____ false rejections.

4.5%

error associated with 1_3s:

random or large systematic error

error associated with 2_2s:

systematic error

two consecutive QC results greater than 2s and on the same side of the mean:

2_2s

for three level controls the 2_2s rule is also expressed as ____.

2/3_2s

error associated with 2/3_2s:

systematic error

error associated with R_4s:

random error

error associated with 3_1s:

systematic error or analytical bias

error associated with 4_1s:

systematic error or analytical bias

may be eliminated by performing calibration or instrument maintenance:

analytical bias

three consecutive results greater than 1s on the same side of the mean:

3_1s

four consecutive results greater than 1s on the same side of the mean:

4_1s

use of 3_1s detects smaller analytical bias than 4_1s and is said to be more ____ to analytical bias.

sensitive

7x control rule is far more ____ to analytical bias than the 12x.

sensitive

instrument manual or test method description, proficiency surveys and interlaboratory QC programs may be used for a laboratory to compare its ____.

standard deviation

laboratories participating in a ____ program receive a set of “unknown” liquid or lyophilized samples

proficiency testing

in an ____ program, laboratories submit monthly data collected for each quality control product tested.

interlaboratory comparison

____ provides statistics collected from repeated daily testing.

interlaboratory comparison

single events that may occur only a few times per year:

proficiency testing

interlaboratory comparison is better/worse than proficiency testing.

better

One way a laboratory can determine whether the precision of a specific test is acceptable is to compare its precision to that of another laboratory performing the same test on the same instrument using the same reagents (laboratory peer group) by calculating ____.

CVR

(CVR) is calculated by dividing the laboratory CV by the laboratory peer group CV obtained from an ____ report.

interlaboratory comparison

for CVR, any ratio less than 1.0 indicates that precision is better/worse than the peer group.

better

for CVR, any score greater than 1.0 indicates that precision is better/worse.

worse

for CVR, any ratios ____ indicate a need to investigate the cause of imprecision.

>1.5

for CVR, any ratios ____ indicate a need for troubleshooting and corrective action.

>2.0

repeated tests such as glucose for diabetic patients or prothrombin times for patients taking coumadin can/cannot be considered reliable when the imprecision is high.

cannot

peer-based estimate of reliability:

SDI

target SDI value:

0.0

SDI value that indicates a perfect comparison with the peer group.

0.0

acceptable SDI value:

</= 1.49

SDI value that is considered lower performance and investigation of the test system is recommended:

1.5-1.99

SDI value that is generally considered to be unacceptable performance and remedial action is usually required:

>/= 2.0

when a new lot of quality control material is put into use, it should be tested alongside the quality control materials currently in use. true or false?

true

in 2016, guidance was updated to allow ____ data points to be used to calculate the mean for a new lot of quality control material.

10

if there is a history of QC data from a period of stable operations of the assay, then the previously established estimate of the SD (or CV) can/cannot be use with the new lot of quality control material, provided the new lot is of a similar formulation (manufacturer) and of a similar target concentration.

can

if historic stable estimates are not available, then at least ____ datapoints are required to be used to calculate the mean for a new lot of quality control material.

20