1. Hematology 425 Quality Assurance
Russ Morrison
September
9/18/2018

2. Why Quality Assurance?
Monitor and weigh the balance between quality and costs in health care
Satisfy stringent regulatory controls
Participation in federal funding programs
Evaluation of clinical outcomes
Reduce risk to the organization
Risk of suboptimal outcomes
Risk of litigation
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3. Quality Control / Quality Assurance
Both terms refer to the control of the testing process to ensure that test results meet requirements
Diagnostic utility
Therapeutic validity
Quality Assurance is overall, coordinated effort to satisfy patients and care givers
Quality Control is activity related to monitoring test systems and making corrections, as needed
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4. Quality Control Definitions
Accuracy – exactness, measured by periodic proficiency testing challenges
Precision – reproducibility, indicator of random error, daily (or as required) quality control replicates
Results that exhibit both precision and accuracy is the goal
Avoid results that are precise, but not accurate (being “precisely wrong”)
See figure 4-1 of text book
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5. Quality Control Definitions
Delta Checks compare results from a prior sample analysis with the result of the same analyte using a current sample
“significant variation” is user defined
Technologist investigates (ie: MCV)
Reference Interval/Normal Range
often refers to the acceptable range of values for the analyte in a healthy person, “reference range” is more appropriate
Reference population used to establish reference range
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6. Quality Control Definitions
Reliability refers to the extent that a method can maintain both accuracy and precision over a period of time. Lab methods are chosen to have a high degree of reliability.
Primary Standard is reference material of fixed and known composition, traceable to national performance characteristics
Secondary Standard is reference material of composition traceable to a primary standard
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7. Statistics in Quality Measures
Normal Distribution Curve
Plus or minus 1 SD includes 68.26% of values
Plus or minus 2 SD includes 95.46% of values
Plus or minus 3 SD includes 99.73% of values
Mean is the center of distribution or point of central tendency, calculated by dividing the sum of the results by the number of results (n if > or equal to 30, n-1 if < 30 results).
Test quality control material performed over a period of time assumes a normal distribution about the mean., as will results of a given parameter performed on a random pool of healthy indivicuals
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8. Statistics in Quality Measures
Coefficient of Variation (CV)
is a measure of precision within a test system, the smaller the CV value, the more precise the analytic test system
CV is calculated as 100*SD/mean
It is expressed as percent
Plus or minus 1 SD includes 68.26% of values
Plus or minus 2 SD includes 95.46% of values
Plus or minus 3 SD includes 99.73% of values
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9. Statistics in Quality Measures
Diagnostic Sensitivity
The proportion of patients with a disease who will have positive test results
Defined by the ratio (a /(a + b)) * 100
a is the number of true positive results and b is the number of false negative results
THINK ABOUT THIS
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10. Statistics in Quality Measures
Diagnostic Specificity
The proportion of patients who are correctly identified by the test as not having the disease
Defined by the ratio (c /(c + d)) * 100
c is the number of false positive results and d is the number of true negative results
Highly sensitive tests are used to screen for a condition, highly specific tests are used to confirm the screen.
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11. Types of Laboratory Error
Systematic-errors within the test system or method (incorrect calibration, broken equipment, failure of the test process to perform accurately or precisely, 2 types)
Constant systematic – magnitude of error remains constant throughout the range, also called a constant bias
Proportional systematic – magnitude of error increases with the concentration of the substance being tested
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12. Types of Laboratory Error
Random – errors that occur without predictability or regularity
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13. Internal Quality Control
Levey-Jennings Control Charts
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14. Internal Quality Control
Normal Levey-Jennings Control Chart
Results randomly distributed about the mean over time
Distribution as expected for normal distribution curve
1 in 20 points may be between 2 and 3 SD (caution), 1 in 100 above 3 SD (act)
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15. Internal Quality Control
Levey-Jennings Control Chart
Shift is a drift in values, may be sudden or gradual
Trend is continuous movement of values in one direction for 6 or more consecutive values
A trend may be thought of as a gradual shift
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16. Internal Quality Control
Levey-Jennings Control Chart
Shift is a drift in values, may be sudden or gradual
Trend is continuous movement of values in one direction for 6 or more consecutive values
A trend may be thought of as a gradual shift
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17. Westgard Rules
1 2s Rule – one control value outside the 2s limit - review
1 3s Rule – one value is outside the 3s limit, random error, investigate
2 2s Rule – 2 consecutive values outside the same 2s limit, investigate
R 4s Rule – 2 consecutive values are more than 4s apart involving both control materials, 1 +2s, 1 -2S, investigate
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18. Westgard Rules
4 1s Rule – 4 consecutive values have been plotted on the same side of the 1s range, may indicate shift or trend
10x Rule – 10 consecutive values fall on the same side of the mean either with same control or 2 or more controls, indicates shift.
1 3s and R 4s rule violations suggest random error while 2 2s, 4 1s and 10x rules suggest systematic errors within the test system.
Computer programmable with warnings to technologists when violations occur.
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19. Other Internal Error Monitors
Moving averages of red blood cell indices (drifts of the moving average outside a defined limit suggest instrument error)
Automated Differential Counting has improved the precision of differentials because it overcomes the non-random distribution of cells on a slide and classifies thousands of cells versus 100 to 200 cells in a manual differential
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20. External Quality Control
Internal Controls monitor precision
External Controls indicate accuracy
Subscription program of qualitative and quantitative controls
Analyzed by hundreds of peer labs using same equipment, same methods
Evaluation is based on how close results compare with the mean opinion of the peer group
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21. Technical Staffing Quality Control
Active continuing education program maintains technical performance at a high level
Imperative to optimal performance
Required by regulatory agencies for accredited laboratories
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22. Overarching Quality Assurance Plan
Goal is to ensure that the quality of laboratory services contributes to the overall delivery of excellent medical care
Focuses on high risk and problem prone areas of system performance
Includes internal and external QC, staff proficiency, pre-analytic, analytic and post-analytic activity, computer functionality, critical values notification and customer satisfaction
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23. QA/QC Group Question Exercise
Proper specimen collection and patient satisfaction are components of:
1. Quality control
2. Quality assurance
3. Reliability
4. Precision 2
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24. QA/QC Group Question Exercise
A patient’s white blood cells are counted on an automated cell counter ten times. The mean white count is 8000/μL and the standard deviation is 300. What is the coefficient of variation (CV)?
1. .04%
2. 2.6%
3. 3.8%
4. 26% 3
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25. QA/QC Group Question Exercise
The CV in the above question indicates that the white blood counts on this cell counter are:
1. Accurate
2. High quality
3. Properly calibrated
4. Precise 4
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26. QA/QC Group Question Exercise
What is the correct interpretation if a 10.0 g/dL hemoglobin standard reads 13.0 g/dL?
1. This is acceptable agreement
2. Imprecise
3. Insensitive
4. Inaccurate 4
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27. QA/QC Group Question Exercise
Interpret the following platelet counts from Mr. Billy Rueben.
Day Day Day 3__
478  109/L  109/L  109/L
1. Day 2 exceeds delta check limits
2. Day 1 and day 3 results are too high
3. Day 1 results were probably collected on the wrong patient
4. All are invalid 1
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28. QA/QC Group Question Exercise
Is the variation in the above platelet counts possible?
1. No
2. Yes, but unlikely
3. Yes, platelet counts typically vary this much from day to day
4. Yes, the patient probably received a platelet transfusion 2
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29. QA/QC Group Question Exercise
Which of the following is the most likely explanation for the platelet counts in Mr. Rueben?
1. Patient is developing thrombocythemia
2. The sample from day 2 contained clumped platelets from a traumatic phlebotomy
3. Patient received a platelet transfusion on day 3
4. This is normal day-to-day platelet variation 2
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30. QA/QC Group Question Exercise
Which of the following is true regarding reference ranges?
1. Should be derived from reference books
2. Need be determined only for adults
3. Can be established by running the test procedure on 10 healthy people
4. Are ranges of values for an analyte in normal healthy people 4
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31. QA/QC Group Question Exercise
A test that is positive in all patients who have the disease but also in some who do not have the disease is:
1. Sensitive
2. Specific
3. Accurate
4. Reliable 1
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32. 1. ANA is a good screening test and anti-DNA a good confirmatory test
The antinuclear antibody test (ANA) is positive in almost all people who have systemic lupus erythramatosus (SLE). It is also positive in some patients who do not have SLE. The anti-DNA is positive only in people with SLE but not in all that do. Which of the following is true?
1. ANA is a good screening test and anti-DNA a good confirmatory test
2. Anti-DNA is a good screening test and ANA a good confirmatory test
3. Both are good screening tests for SLE
4. Neither of these tests is valid 1
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33. QA/QC Group Question Exercise
A purchased hemoglobin standard is used to adjust a hemoglobinometer. This standard is being used as a:
1. Control
2. Reference
3. Delta check
4. Calibrator 4
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34. QA/QC Group Question Exercise
The tubing that brings the lyse reagent to the hemoglobin cuvette on an automated cell counter is pinched and not delivering any reagent. All hemoglobin values are greater than 20 g/dL. This represents what type of error?
1. Random
2. Imprecision
3. Constant systematic
4. Proportional systematic 3
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35. QA/QC Group Question Exercise
On day 29 in a month one of the two controls was between 2 and 3 SD. What is the correct procedure to follow?
1. Stop running patients until an investigation is completed
2. Rerun the control and if acceptable continue with patients
3. Recalibrate the instrument
4. Open new vials of controls and repeat both controls 2
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36. QA/QC Group Question Exercise
The control values for the prothrombin test were ranging between the mean and minus one standard deviation. Starting on day 20 of the month the values consistently were between +1 and +2 SD. This is an example of a:
1. Shift
2. Trend
3. Random error
4. Deviation 1
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37. QA/QC Group Question Exercise
Which of the following would most likely be associated with the above situation?
1. Operator error
2. Burned out light source
3. Instrument miscalibrated
4. Starting a new lot number of thromboplastin reagent 4
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38. QA/QC Group Question Exercise
Which of the following patients should not be included in indices moving averages?
1. Chemotherapy recipients
2. Infants
3. Obstetrical
4. Surgical 2
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39. QA/QC Group Question Exercise
A laboratory comparing its results to other labs is an example of:
1. Precision monitoring
2. Internal QC
3. External QC
4. Delta checks 3
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40. QA/QC Group Question Exercise
A laboratory gets numerous complaints regarding the length of times it takes hematology results to get to the emergency room. What would be an appropriate response?
1. Make this a quality assurance project
2. Ignore the complaints
3. Explain why it takes so long
4. Tell the employees to work faster 1
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41. QA/QC Group Question Exercise
The best way to prevent errors in the laboratory is to assure:
1. Quality instruments
2. Well trained, conscientious workers
3. Quality management
4. QC consistently being between ±2 SD 2
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