Lab management Flashcards

1
Q

What is standardisation?

A

Trueness based agreement
Comparable results with traceability to a primary reference standard

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2
Q

What is Traceability?

A

The unbroken chain of calibrations connecting a routine result to a primary reference standard

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3
Q

What is Harmonisation?

A

Consensus based agreement.
Comparable results without traceability to a primary reference standard

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4
Q

Formula for positive likelihood ratio

A

sensitivity / (1-specificity)

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5
Q

Formula for negative likelihood ratio

A

(1-sensitivity)/specificity

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6
Q

What is the Limit of Blank (LoB)?

A

Highest apparent concentration of analyte free material.

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7
Q

What is the Limit of Detection (LoD)?

A

Lowest concentration of analyte confidently measured
(Lowest concentration confidently separated from the blank)

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8
Q

What is the Limit of Quantitation (Functional Sensitivity)?

A

Lowest concentration of analyte reliably measured

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9
Q

What is the definition of Uncertainty of measurement? (as per ISO15189)

A

Parameter associated with the result of measurement that characterises the dispersion of values

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10
Q

What are the 6 steps of EBLM?

A
  1. Ask - frame a PICO question
  2. Acquire - search the literature
  3. Appraise - critically review the literature
  4. Analyse - systematic reviews and meta analyses
  5. Apply - develop and promote guidelines
  6. Assess - audit/evaluation
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11
Q

What does PICO question stand for in evidence based laboratory medicine?

A

Patient
Intervention
Comparator
Outcome

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12
Q

What does STARD stand for?

A

Standards for Reporting Diagnostic Accuracy studies

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13
Q

Formula for correcting sodium concentration for hyperglycaemia

A

Na (corrected) = Na (measured)+ Glucose/4

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14
Q

Calculation to estimate VLDL from triglycerides (using mmol/L)

A

Trig/2.2

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15
Q

Formula for creatinine clearance

A

(Urinary Cr x Vol)/(Plasma Cr x Time)

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16
Q

What calculations are available to estimate renal function?

A

Cockcroft and Gault
MDRD formula
CKD-EPI

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17
Q

In pre renal renal failure, what would you expect the fractional excretion of sodium to be?

A

<1%

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18
Q

Components of a patient based real time quality control system

A

Calculations algorithm
Block size
Truncation (filtering) limits
Control limits (or rules)

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19
Q

Method validation involves assessing… (name 8 components)

A
  • Accuracy
  • Precision
  • LoD and LoQ
  • Working concentration range (linear range)
  • Standard measurement uncertainty
  • Interference studies (specificity)
  • Stability studies
  • Establishing the reference range
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20
Q

Minimum scope for Method Verification

A
  • intra-assay precision and accuracy
  • inter-assay precision and accuracy
  • correlation with existing method
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21
Q

Statistical test used for non-parametric data to determine if the observed frequencies were as expected?

A

Chi-squared test

22
Q

Statistical test used for non-parametric data to determine if 2 measurements for a subject differ significantly?

A

Wilcoxon Signed Rank Test

23
Q

Statistical test for parametric data used for answering - is there a difference in the mean of 2 groups of data which is statistically significant?

A

Students t-test

24
Q

Coefficient (reported as r) which measures if there is a linear relationship between 2 groups of data.

A

Pearson’s Correlation Coefficient

25
Q

Hierarchy of Quality Specifications - Stockholm Criteria

A
  1. Studies on clinical outcomes
  2. Clinical decisions based on BV, clinical opinion
  3. Published professional recommendations
  4. Performance goals set by regulatory bodies of EQA schemes
  5. Goals based on current state of the art as demonstrated by current or EQA data
26
Q

Milan models for APS

A

Model 1 - based on effect of analytical performance on clinical outcomes
Model 2 - Based on components of biological variation of the measurand
Model 3 - Based on **state of the art **

27
Q

Westgard rules that = QC Failure

Do not report patients

A

1 3S
2 2S
R 4S

28
Q

Westgard rules = QC warning

A

1 2S
4 1S
10X

29
Q

Capability Index =

A

APS/Sd of assay

30
Q

What Capability Index is considered acceptable?

A

> 2 - minimum
3 - desired
4 - excellent
6 - 6 sigma

31
Q

Measurement of Uncertainty (MU) =

A

2 x SD of the assay (or CV%)

This gives us a 95% confidence of the “true result”

32
Q

What does NPAAC stand for?

A

National Pathology Accreditation
Advisory Council

establish guidelines and standards for accreditation

33
Q

What does NATA stand for

A

National Association of Testing Authorities

34
Q

Types of bias in diagnostic accuracy studies

A
  • Spectrum bias
  • Selection bias
  • Verification bias
  • Blinding
  • Publication bias
35
Q

Strategies to improve testing appropriateness can be classified as (3 categories):

A
  • Restriction
  • Feedback
  • Education
36
Q

What is error

A

Difference between the measured value and the reference value

37
Q

Optimal specification for imprecision is …

A

CVa </= 0.25 CVi

38
Q

Desirable specification for imprecision is …

A

CVa </= 0.5 CVi

39
Q

Minimal specification for imprecision is…

A

CVa </= 0.75 CVi

40
Q

Milan consensus hierarchy for APS

A

Model 1 - based on the effect of analytical performance on clinical outcomes
Model 2 - Based on components of biological variation of the measurand
Model 3 - Based on state of the art

41
Q

What is the Diagnostic Odds Ratio

A

DOR = (TP/FN) / (FP/TN)

Odds of positivity in subjects with disease relative to odds in subjects without disease

Does not depend on disease prevalence

42
Q

Nomogram used to calculate post test probability

A

Fagan nomogram

43
Q

Definition of Commutability

A

Property of reference materials
Defined as those materials having the same inter-assay relationships to those of clinical samples

44
Q

Factors to consider in assessing new lots

A
  • Samples
  • Statistics
  • Acceptance criteria
  • Actions
45
Q

Steps to assess Clinical Utility

A
  1. Review state of the art
    - use STARD criteria
  2. Decide an approach to determination
  3. Design your evalution
  4. Plan your evaluation
  5. Decide the levels of evidence that are required
46
Q

What does JCTLM stand for?

A

Joint Committee for Traceability in Laboratory Medicine

47
Q

How does Deming linear regression measure residuals?

A

Residuals are measured at right angles to the line of best fit

Vs in ordinary linear regression residuals are at vertical

48
Q

What is the main advantage of Passing Bablok compared to other forms of linear regression?

A

More robust to outliers as uses medians to calculate slope and intercepts

Lines drawn between all pairs of data points and median slope calculated

49
Q

Number of samples recommended to calculate LoB or LoD

A

20 if verifying
60 if establishing

50
Q

Analytical sensitivity is also referred to as..

A

The Limit of Detection

51
Q

Functional sensitivity is also referred to as..

A

The Limit of Quantitation

52
Q

ISO standard for POCTs

A

ISO 22870