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CC > Quality Control > Flashcards

Quality Control Flashcards

1
Q

Ability of a method to measure the smallest concentration of analyte

A

Sensitivity

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2
Q

Ability of a method to measure only the analyte of interest

A

Specificity

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3
Q

Nearness to the true value

A

Accuracy

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4
Q

Determines how much of analyte can be identified in a sample

A

Recovery study

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5
Q

Determines a specific compound that affects the lab tests

A

Interference study

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6
Q

Used to assess the presence of error im actual patient sample

A

Sample comparison study

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7
Q

Repeated results that agree with one another

A

Precision

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8
Q

Degree by which a method is easily repeated

A

Practicablity

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9
Q

Ability of a method to maintain accuracy and precision over a period of time

A

Reliability

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10
Q

Ability of a method to detect the true positive

A

Diagnostic sensitivity

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11
Q

Ability of a method to detect the true negative

A

Diagnostic Specificity

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12
Q

Involves analyses of control samples together with the patient specimen

A

Intralab or Internal QC

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13
Q

Involves proficiency testing programs that periodically provide samples of unknown concentrations to participating laboratories

A

Interlab or External QC

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14
Q

Note: some proficiency tests are QUALITATIVE however Chemistry tests should be QUANTITATIVE

A

Remember this!

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15
Q

Note:

In external QC, difference of greater than 2SD indicates that the lab is not in control

A

Remember this!

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16
Q

Objectives of QC

A

Stability of machine, reagent and operator

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17
Q

Note:
Accuracy of any assay depends on the control solutions. Chemistry assay used 2 levels of control solutions while Immunoassay used 3 levels of control solutions

A

Remember this!

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18
Q

The different control materials should be analyzed for how many days?

A

20 days

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19
Q

For highly precised assays such as blood gases, how many days is the analysis

A

5 days

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20
Q

Expected values represented by intervals of acceptable values with upper and lower limit

A

Control Values

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21
Q

How are control limits calculated

A

From the mean and SD

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22
Q

The ideal control/reference limit

A

(+/-) 2SD

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23
Q

Characteristic of ideal QC material

A
  • Resembles human sample
  • Inexpensive and stable for long period of time
  • No communicable disease
  • No matrix effect
  • With known analyte cocentration
  • Convenient packaging
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24
Q

Note:
QC materials should be available for 1 year (same lot number)

Bovine QC materials are used but not for immunochem, dye-binding and bilirubin assays

Stabilized frozen controls do not require reconstitution

A

Remember this!

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25
Q

Gold standard for external qc testing

A

CAP Proficiency Testing

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26
Q

Note: Method Evaluation

  • 40-100 samples should be ran by each method in duplicate on the same day over 8-20 days ideally within 4 hours
  • If only 40 samples will be measured, daily analysis in duplicate of 2-5 specimens should be followed for atleast 8 days
  • Most impt. characteristic of method evaluation is to DETERMINE IF THE TOTAL ERROR IS LESS THAN THE ALLOWABLE ERROR
A

Remember this!

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27
Q

What are the types of error

A

Random, systematic, constant, proportional, clerical errors

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28
Q

Error that is due to chance; vary from sample to sample; due to instrument, operator and environmental condotions

A

Random error

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29
Q

Errors that influences observations consistently in one direction; detected as either positive or negative bias; related to calibration problems, deterioration of reagents etc

A

Systematic error

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30
Q

Refers to the difference between the target value and the assayed value; dependent on the sample concentration

A

Constant error

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31
Q

Exists when the difference between the test method and the comparative method values is proportional to the analyte concentration

A

Proportional / Slope / Percent Error

32
Q

Highest frequency; occurs with the use of handwritten labels and requests

A

Clerical error

33
Q

Note:

First step of method evaluation is the PRECISION STUDY which estimates RANDOM ERROR

A

Remember this!

34
Q

Most error free means of requestinh laboratory tests

A

Online computer output

35
Q

Note: Allowable error
* is based on the quantity of error that will negatively affect the clinical decisions

  • the long term precision is sufficient if the total imprecision is less than 1/3 of the allowable error
A

Remember this!

36
Q

It is the measure of central tendency

A

Mean

37
Q

Measure of a the dispersion of values from the mean

A

SD

38
Q

Most frequently used measure of variation

A

SD

39
Q

Index of precision

A

Coefficient of Variation

40
Q

Used to compare the means or SD of two groups of data

A

Inferential statistics

41
Q

Used to determine whether there is a significant difference between the SD of two groups of data

A

F Test

42
Q

Midpoint of distribution

A

Median

43
Q

Most frequent observation

A

Mode

44
Q

Difference between the highest and lowest score in the data

A

Range

45
Q

Difference between the value of a data point and the mean value divided by the group’s SD

A

SD Index

46
Q

Used to determine whether there is a significant difference between the mean of two groups of data

A

T-test

47
Q

It is the system that ensures accuracy and precision in the laboratory

A

Quality Control System

48
Q

Describes the distribution of data around the mean

A

SD

49
Q

Is used to observe values of control materials over time

A

QC Chart

50
Q

It is a population probabilty distribution that is symmetric about the mean; occurs when data elements are centered around the mean with most elements close to the mean

A

Gaussian curve / Bell-shaped curve

51
Q

Calculates the difference between QC results and the target means; V-shaped; requires computer implementation

A

CUSUM

52
Q

Used to compare results obtained on a high and low control serum from different laboratories; X and Y axis

A

Youden/Twin plot

53
Q

Most widely used QC chart in the clinical laboratory

A

Shewhart Levey-Jennings Chart

54
Q

Control values that either increase or decrease for six consecutive days

A

Trend

55
Q

Control values that distribute themselves on one side of the mean for six consecutive days

A

Shift

56
Q

Control values that are far from the main set of values

A

Outliers

57
Q

Establish criteria for deciding whether an analytic process is out of control

A

Multirule

58
Q

Warning rule

A

1(2)s

59
Q

Rejection rule; One control exceeds 3SD; Needs correction

A

1(3)S

60
Q

Last 2 controls exceed either mean +/- 2SD

A

2(2)S

61
Q

Last or any four consecutive control results exceed either mean +/-1SD

A

4(1)S

62
Q

Difference between the highest and lowest control result

A

R4S

63
Q

Ten consecutive results are on the same side of the target mean

A

10x

64
Q

Acceptable reference limit

A

+/- 2SD

65
Q

99% confidence

A

+/- 3SD

66
Q

68% confidence

A

+/- 1SD

67
Q

95% confidence

A

+/- 2SD

68
Q

Is the difference between two consecutive measurements of the same analytes on the same individual

A

Delta check

69
Q

Are used to measure systematic errors or inaccuracy caused by substances other than the analyte

Ex: hgb, lipids, bilirubin

A

Interference experiments

70
Q

Is the concentration range over which the measured concentration is equal tp the actual concentration without modification of the method

A

Linear range

71
Q

Absurd value; detect sample contamination or dilution

A

Physiologic unit

72
Q

Testing performed outside the confines of central laboratory, usually by non-laboratorian personnel; decentralized testing

A

Point of care testing

73
Q

Is a systematic action necessary to provide adequate confidence that the laboratory services will satisfy the given medical needs for patient care

A

Quality assurance

74
Q

It shows whether a method can measure all the analyte or just a part of it

A

Recovery experiment

75
Q

It is the range of values into which 95% of nondiseased individuals will fall

A

Reference limit

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