Quality control and Quality assurance

Question 1

General definition of quality

Answer 1

General definition of quality - Value of services

Question 2

The Product produced by clinical labs is INFORMATION

Answer 2

data or results

Question 3

Why monitor quality in a Clinical Lab

Answer 3

• Ensure that results delivered are valid and the information is of value and is reliable
• If the QC results are off, what does it say for the patient results?
• Compliance with CLIA Standards and regulations

Question 4

Quality levels

Answer 4

QC–> QA–> TQM

Question 5

Standard( calibrator)

Answer 5

• A material of known value used to standardize (calibrate) any analytical
  procedure and thereby determine the value of an unknown (patient)
• Use for verification/validation

Question 6

Primary standards

Answer 6

• Primary
• A solution generally containing a single purified solute (e.g. glucose) in a pure
  solvent (e.g. water).

Question 7

Secondary standards

Answer 7

• Secondary
• A material with an established value(s) determined by assay against a
  primary standard. It may contain one or more constituents.

Question 8

Serum calibrator

Answer 8

• contains numerous constituents (solutes)
• uses serum as the solvent
• solutes are of equivalent purity to those used in primary standards
• solutes added to solvent (serum) on the basis of analytical weighings.

Question 9

Controls

Answer 9

(Quality Control)
* A stable substance which contains one or more known constituents used to
verify the accuracy and precision of a method * Use for runs

Question 10

Shelf life-

Answer 10

compare usage
* Use 1 mL/day
* Control 1: $2/mL, 100 mL, 1 month shelf life * Control 2: $5/mL, 100 mL, 6 month shelf life

Question 11

Box pricing

Answer 11

• Compare price per mL, not per box

Question 12

Ideal:

Answer 12

Three levels
* Low level (abnormal) * Normal level
* High level (abnormal)

Question 13

Linearity of instrument

Answer 13

• Controls must read within the linear range of the instrument

Question 14

TSH Immunoassay

which one is correct

Immunoassay Control Set A
* Low Level (1.03 – 1.23 μIU/mL)
* Normal Level (7.5 – 9.6 μIU/mL)
* High Abnormal Level (27.9 – 34.5 μIU/mL)

Immunoassay Control Set B
* Low Level (3.0 – 5.0 μIU/mL)
* Normal Level (8.0 – 10.0
μIU/mL)
* High Abnormal Level (45 – 55 μIU/mL)

Lab considerations

Answer 14

Laboratory Considerations:
1. TSH Decision Limits: Low (<3 μIU/mL), Normal (3-10
μIU/mL), High (>10 μIU/mL
2. Linearity of Instrument: Linear to 50 μIU/mL

Question 15

Levy Jennings Chart

Answer 15

• If a control point falls outside the +/- 2SD of the mean value, the control results are considered to be “out of control” and patient samples cannot be run or reported.
• NOTE: ONE control point out of 20 outside of +/- 2 SD is acceptable (95% confidence limits)
• If the control values falls within the +/- 2SD of the mean value, the QC results are “in control” and patient results may be reported

Question 16

Westgard multi- rules

Answer 16

• set of rules based on a statistical analysis of controls
• System of criteria to determine if a system is “in control”
• Can be used with one control (within) or more than one control (across)

Question 17

Multirules

Answer 17

• Simply: More than one rule
• Example:
• My diet allowance:
• Onedonutperday
• No more than 3 donuts in a week
• Cannot have 1⁄2 of a donut more than 5 days in a row

Question 18

West guard rules

Answer 18

Set of rules to determine if analytical run is “in control” or “out of control”

Question 19

13s rule

Answer 19

when a single control measurement exceeds the mean plus 3s or the mean minus 3s control limit.

Question 20

12s

Answer 20

-when control limits are set as mean plus/minus 2s.
- when outside this limit then the machine shuts off.

Question 21

22s

Answer 21

Reject when 2 consecutive control measurements exceed the same mean plus 2s or the same mean menus 2s control limit

Question 22

R4s

Answer 22

Reject when 1 control measurement in a group exceeds the mean plus 2s and another exceeds the mean minus 2s

Question 23

41s

Answer 23

Reject when 4 consecutive control measurements exceed the same mean plus 1s or the same mean minus 1s control limit.

Question 24

41s rule

The criteria which must be met to violate this rule are

Answer 24

-Four consecutive results
- greater than 1s
- on the same side of the mean

Question 25

There are two application to the 41s rule

Answer 25

1. Within control material (e.g. all Level I control results) 2. Across control materials (e.g., Level I, II, and III control results in combination). Within control material violations indicate systematic bias in a single area of the method curve while violation of the across control materials application indicates systematic error over a broader concentration.

Question 26

Warning rule 12s

Answer 26

* If occurs once in every 20 runs, very important to keep results in QC statistics to maintain same bell curve – if rejected will continually make the bell curve narrower. * If occurs more than once in every 20 runs then indicates a dispersion problem and imprecision. The result should be rejected from QC statistics.

Question 27

Additional rules

Answer 27

*Random Error Mandatory rules: 13S and R4S detect *Systematic Error Mandatory rules: 22S and 10X detect bias problems.

Question 28

10x rule

Answer 28

Reject when 10 consecutive control measurements fall on one side of the mean. you will sometimes see some modifications of this last rule to make it fit more easily with Ns of 4: 8x - reject when 8 consecutive control measurements fall on one side of the mean.

Question 29

8x

Answer 29

reject when 8 consecutive control measurements fall on one side of the mean.

Question 30

8x

Answer 30

reject when 8 consecutive control measurements fall on one side of the mean.

Question 31

Rules for using the rules At least two control levels

Answer 31

* At least two control levels (i.e. normal and abnormal) must be performed with each run of patient samples or on each timed shift.

Question 32

Rules for using the rules Test the 12s rule if

Answer 32

* Test the 12s rule. If both control values are within +2 standard deviations, accept the run and report out the patient test results. If either control is outside +2 standard deviations, look at the next multi-rule. Hold the patient test results. Once any multi-rule has been broken, then the run is rejected and further analysis of the multi-rules is not continued. Then, problem solving begins.

Question 33

Test the 13s rule if

Answer 33

* Test the 13s rule. If either of the control results was outside + 3 standard deviations, then reject the run. Do not report the patient test results.

Question 34

Tests the 22s rule if

Answer 34

* Test the 22s rule. First, review the control results for the normal and abnormal control. If both controls were greater than +2 or –2 standard deviations in the same direction, then reject the run and do not report out the patient results. Secondly, review the results for the last two normal controls and then the results for the last two abnormal controls. Look for results that are greater than +2 and -2 standard deviations in the same direction. If found, then reject the run. Do not report out the patient results.

Question 35

Tests the R4s rule if

Answer 35

* Test R4s rule using both the normal and abnormal controls in the same run. If one control is greater than +2 standard deviations and the other is greater than –2 standard deviations, reject the run.

Question 36

Tests the 41s rule if

Answer 36

* Test the 41s rule for the last three normal controls and then the last three abnormal controls. If the last three normal or abnormal controls are greater than +1 or -1 standard deviation, then reject the run. Examine the last three controls, looking at both the normal and abnormal controls. If the last four controls of normal and abnormal levels were greater than +1 or –1 standard deviation, then reject the run.

Question 37

Tests the 10X rule if

Answer 37

* Test the 10x rule by looking at the last 10 controls run, whether normal or abnormal. Look to see if the results all fall on one side of the mean or the other side. If found, reject the run.