L1 - Quality Assurance Flashcards

1
Q

What are the three general sources of error in biochemical analysis based on time-scale?

At what stages in the process of analysis do these occur?

A

Pre-analytical - before sample gets to the lab
Analytical - during analysis
Post-analytical - what happens to the results

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2
Q

Give three sources of pre-analytical errors

A

Poor sampling technique, inappropriate containers, storage or transport, not enough sample, errors in patient ID

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3
Q

How can pre-analytical errors be minimised?

A

Training staff who are to be taking samples, get receptionists to check samples, use barcodes to prevent errors in patient ID

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4
Q

Give three sources of analytical errors

A

Poor precision/random errors, poor accuracy/systematic errors, poor quality assurance

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5
Q

How can analytical errors be minimised?

A

Automation, method validation, quality procedures

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6
Q

Give three sources of post-analytical errors

A

Errors in collation or recording of results, inappropriate reference ranges

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7
Q

Define accuracy

A

Ability to measure the true value

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8
Q

Define precision

A

Ability to produce consistent results

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9
Q

Define sensitivity

A

Ability to identify those with a condition (fewer false-negatives)

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10
Q

Define specificity

A

Ability to exclude those without a condition (fewer false-positives)

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11
Q

Define analytical sensitivity

A

Smallest amount of analyte a test can distinguish from zero

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12
Q

Define analytical specificity

A

Ability to measure only the analyte in question

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13
Q

What are the two types of error in biochemical analysis?

A

Systematic error and random error

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14
Q

Define systematic error

Are these precise or accurate?

A

Values are systematically too high OR too low

Precise

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15
Q

Define random error

Are these precise or accurate?

A

Results are scattered

Accurate

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16
Q

Give an example of a systematic error

A

Zero error - not zeroing equipment before use means all results are off by the same amount

17
Q

Give an example of a random error

A

Human errors such as inconsistent techniques

18
Q

What are the two types of quality assurance programmes?

A

Internal Quality Control (IQC)

External Quality Assessment (EQA)

19
Q

What do internal quality control measures consist of?

A

Measuring IQC materials (substances with known concentrations of analyte) against samples

20
Q

What does external quality control consist of?

A

External bodies collect data on lab performance and compare to other labs to determine if there are any problems

21
Q

What is a clinical audit?

A

A review process that aims to improve quality of care

22
Q

What are the Westgard rules used for?

What does a 1, 2S rule mean?

A

Rules that help labs to determine if there are problems with the accuracy of their procedures

1 control measure lies outside 2SD of the mean

23
Q

Define a reference range

A

Range of values associated with healthy individuals

Central 95% within 2SD of the mean

24
Q

Give five factors that can affect the reference range used

A

Age, sex, diet, smoker, pregnancy, stress, exercise timing of sample collection