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RCPA Immunopathology Part 2 > 2.1 Quality management > Flashcards

2.1 Quality management Flashcards

1
Q

What are the characteristics of a calibrator?

A

Calibration is important for reliable quantitation of an analyte

  • metrological traceability ; related to CRM certified reference material, national/int standard through unbroken chain of comparisons
  • commercially supplied reputable source (lot #, expiry, conc, traceable)
  • matrix similar to testing sample
  • stable
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2
Q

What is the role of the calibration curve and what are important characteristics of the curve?

A

CC relationship between instrument response and known conc of analyte in calibrators, to provide a result for a sample within an acceptable range

  • min 6 calibrators- blank with only matrix
  • independent calibrators not dilutions of a master
  • range 0-150% of conce likely to be encountered
  • evenly spaced over range
  • run in duplicates
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3
Q

How are in house controls formed?

A

Possible sources:

-pooled samples from multiple patients
-a large specimen from one patient
(for some antibody PCS) -could have plasmapheresis samples

Once obtained
-ideal to have same matrix as patient
-near the clinical significant cut off level/within clinically significant measuring range
-stable
-sufficient volume 
different levels of control

Establish acceptable range for PCS

  • 15-20 repeats on different runs/operators
  • establish sd/cv for PCS and range
  • may chart on LJ
  • verify result from another lab/method
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4
Q

What are desirable controls/ characteristics of a good control?

A

Control is a specimen with known quality/quantity which allows performance assessment /assess test validity

  • around the cut off
  • covers analytical concentration
  • clinical relevant level
  • similar matrix to patient sample
  • good stability/easy storage/adequate quantity
  • no need for dilution
  • cost effectiveness
  • minimal lot to lot variation
  • native rather than recombinant
  • safe (virus tested)
  • should be independent from manufacturer (commerical or pooled in house control)
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5
Q

What is a drift pattern and what can be the causes of this?

A

Drift- at least 5 consecutive values on one side of the mean

Instrument or control issue

Instrument: accum debris, incubation chamger temp, light filter, deterioration calibration, light source

Reagent: expiry/degradation

Action: recalibration of the instrument or change QC lot

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6
Q

What is a shift pattern and what can be the cause of this?

A

A sudden abrupt change

Reagent- new calibration, new curve, lot/change in formulation

Control- reconstitution, different lot number, diff bottle, storage

change in protocol

lab condition- temperature, water, contam

Failure in sampling system, mixing , centrifuge, washer, technician

Instrument failure- major maintenance

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7
Q

What is bias and what types are there?

A

Bias- systematic error- disagreement between the measured value of an analyte and its true value

Constant- same across measuring range

Proportional- higher error at higher concentrations, lower at lower concn (starts at 0)

Error stated as % bias
On linearity graph*
(low b+mid b+ high b)/3

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8
Q

What is imprecision? and what can make precision worsen?

A 
Random error
High CV (bad precision)

Can occur with
(reagent, machine, operator)
- poor technique/malfunctioning equipment
- reagent; air bubbles, sampling errors, improper mixing
- incorrect pipetting; imprecise, ill fitting tip, clogging
- power fluctuation
- contaminated water

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9
Q

You are out on EQA - approach

A

First state assay, method, whether we are in/or out, random or systematic
- unacceptable /acceptable

  1. Investigate that EQA
    - Bring out run
    - pre-analytical; correct sample, handling, storage
    - analytical; calibrator change, reagent lot change, technique change, staff change/operator following SOP, instrument parameters, maintenance
    - post analytical; transcription error,
  2. Look at method group
    - methodology issue
    - if out within method? reagent change
  3. pattern previous cycles
    - alone or with method
    - ? method change
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10
Q

What is the hierarchy of preferred methods for establishing performance goals?

(stockholm hierarchy)

A
  1. goals based on clinical outcome
  2. goals based on clinical decision making
    - clinician survey
    - biological inter and intra individual variability
  3. goals based on expert opinion
  4. goals based on peer capability eg EQA
  5. goals based on state of the art
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11
Q

What are the causes of low lymphosum?

Accepted >95%

A
  1. Malignant/aberrant population
  2. Interfering substance eg. inadequate cell lysis, debris, nucleated red cell
  3. Reagent deterioration and binding issues
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12
Q

What is quality?
What are some of the markers of quality in a laboratory?

How is quality applied in the laboratory?

A

Quality

Objectives of quality

  • support high quality health care; reduce mort/morb/economic loss
  • credibility of lab; consistency (accuracy/precision), right result first time, every time
  • generate confidence in lab results

Man driven:on site audit; internal/external, accreditation
Material driven; internal, external, EQA

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13
Q

What are some of the quality controls used in flow?

A

Pre-analysis

  • CS& T beads; polystyrene beads 3 diff intensities
  • check fluidic system, laser(s), optics, and electronics; LJ chart PMT voltage
  • rainbow beads: fluoresce in all channels 8 colours 3 lasers, check application settings; median MFI for each fluorochrome LJ chart; check voltage settings to optimise visual
  • CS& T beads fail then
    • check correct beads run expiry/storage
  • -beads warm otherwise clump
  • -rinse fluidics bleach/clean
    • de gas flow cell air bubbles
    • laser warm up
    • optics/detectors instrument maintenance
    • corect values entered

– engineer

Other controls;

  • lymphocyte subsets CD chex LJ chart
  • healthy patient control
  • other post analytical lymphosum, T cell sum, delta check
  • EQAP
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14
Q

Pitfalls of flow ?

A

preanalytics - correct patient sample, cell viability, handling, storage,

analytical

  • instrument set up/tracking (fluidics, lasers, optics, electronics),
  • QC specific to run
  • processing; lysis, antibody (expiry, non sp binding poly vs mono), incubation, washing inadequate
  • interfering antibodies
  • instrumentation maintenance, contamination
  • operator within SOP

Gating/compensation
Voltages
Raw plots

post analytics

  • QC lymphosum
  • interpretation
  • transcription
  • rounding issue
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15
Q

What are critical results? What is the procedure in your lab

A

Critical- results that will affect or change a patient’s management and should be communicated urgently

e.g vasculitis, GBM, dsDNA/ENA SSA preg, neuronal, tryptase, HIV, DHR,

NATA requirement- documented procedure

Procedure

  1. scietnsit tells reg/smo of result
  2. Result checked
  3. Interim
  4. phoned
  5. FU w verify/document/
  6. document
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16
Q

Changing lot number of QC material, how would you go about changing over to the new lot number batch?

A
  • Run in parallel old and new QC
  • Run 20 values sequential runs or/and within runs
  • Compare mean and SD value with previous QC to see if acceptable performance limits for new QC material
  • Avoid changing lots of reagents whilst change in new QC
  • Document in multi QC program
  • Periodic monthly (ACT) QC checks to refine performance characteristics
17
Q

What are some of the ways to improve TAT?

A
  1. Test selection/order entry- easy access/standardisation
  2. Specimen collection/delivery- access to info handling/phlebotomy notice/barcodes/delivery systems
  3. Testing- automation, minimal downtime, automated dilutions, verifications, incomplete lists
  4. Reporting- interface, preliminary results

Evaluate flow to maximise efficiency

18
Q

What are the causes of a gradual drift/trend?

A

Trend of at least 5 consecutive values- gradual change

Reagents/controls- incorrect storage/unstable/refridgerator problem/degradation
Analyser issues
Lab temperature

Fix: recalibrate instrument or use fresh control

19
Q

What can cause between assay imprecision?

A
  • reagent lot fault
  • contro problem
  • variation in coated beads/well/tube
  • other analytics; pipette/washing/centrifugin
20
Q

What can cause within plate/ poor reproducibility

A
  • excessive time taken to add samples/controls
  • multichannel pipette
  • inconsistent washing
  • poor distribution of ab in sample(mixed if thawed)
  • inconsistent incubation
  • reagent lots diff
  • inconsistent washing
21
Q

What can cause high background signal?

A
  • poor quality water for washing plate
  • substrate solution deteriorated
  • insufficient washing
  • cross reac/non specific binding
  • conjugate concentrate too high
  • washer microbial contam
  • reader malfunctioning not blanked properly - repeat zero reading
22
Q

What can cause low optical density?

A
  • lab temp too low
  • too many wash cycles
  • incubation period too short
  • plate/reagents too cold
  • if no colour then conjugate not added/wrong bottle used
  • assay plate read at wrong wavelength/reader malfunctioning
23
Q

What is the difference between a calibrator and control?

A

Calibrator- point of reference accurate known value to calibrate a method and standardise results, used to establish relationship between amount of signal produced and the analyte concentration

curve, single or multipoint, usually from kit

Control- determines validity of run and monitor performance of assay by assessing precision

known value, can be 1st /3rd/ PCS, pos/neg charted on LJ chart

24
Q

How do you establish value of a new QC material?

A

Run at least 20 times (30) over different batches and runs

Calculate mean, SD and CV of data
mean +/-2 SD of the mean

Needs satisfactory CV
Plot on LJ chart

25
Q

What are the Westgard rules?

A

Set of rules based on statistics for accepting, rejecting/concern for individual runs of an assay to identify variations in excess to what is expected

  • 1 2s warn
  • 1 3s reject, 2 2s reject , 1 4s, 4 1 s, 10 1s
26
Q

What is a Levey Jennings chart? And how do you construct one?

A

To observe trends with internal QC analyses over time to allow preventative quality action on lab performance

Y-axis- assay value with mean, 1SD, 2SD, 3SD and x-axis run number

Allows analysis of assay performance over time, ID shift and drift

27
Q

What is open disclosure?

A

NPAAC open discussion about incident which could have/or did result in harm

  • apology
  • factual explanation
  • patient opportunity to relate experience
  • discussion of consequences
  • steps being taken to manage event/prevent recurrence

two way discussion

28
Q

What is the complaint process at ACT pathology?

A

patients- consumer and carer feedback- CHS review then forward to ACT pathology

ACT pathology phoned complaints form

external- customer services dept of ACT pathology

QIR- community/Riskman- within CHS

  • event
  • remedial action
  • root cause analysis
  • corrective and preventative action

QIR- chief scientist/manager dept as owner
Riskman- executive director/medical director

Serious complaints- forwarded to ACT pathology management committee PMC

Quality manager review organisation deficiency, close the report

29
Q

What is quality? Outline steps taken by your lab to ensure quality

A

Quality- degree to which an entity/service satisfies a specified set of requirements

Requirement of accreditation/ stipulated in standard for quality and competence in ISO 15189

There is a quality management system, and a quality manual

  • quality policy
  • quality plan
  • quality objectives
    Upheld by quality improvement office, quality manager, liaising with ACT path LSC and executive director

Regarding management requirements

  • organisation
  • referral lab
  • corrective action/ complaints
  • non conformance
  • control of records
Technical requirements
- personnel
- environmental
- equipment/technology
- pre exm process
- exam process (TAT, internal QC)
- results reporting/release
assurnace of quality
-- internal audits
- QAP programs
30
Q

What are NATA requirements for verbal results?

A
  • clear, secure and timely manner to requesting clinician
  • documented policy (name of person providing/receiving, date, time, reading back report)
  • FU w electronic or har dcopy asap
  • list of critical tests
31
Q

What are the principles of equipment maintenance?

A

Manufacturers recommend regular schedule of equipment maintenance, daily/weekly/monthly
- for systematic and routine cleaning
- adjustment
- replacement
To ensure equipment performs at max efficiency/lifespan optimised

Maintenance log/plan for each equipment

  • assign resonsibility
  • written policy
  • staff training
  • manufacturer/vendor contact, maintenance contract
32
Q

what is a non conformity?

A

Any event that does not conform with the standard or usual procedures of the lab or its quality management system

Examples;

  • definite or potential error
  • complaint
  • safety issue

CAR forms
- event, immediate corrective action, root cause analysis, preventative, discussion, then close- NATA audits

33
Q

What are the important components of an amended report?

A
  • clearly indicate it is a revision/amendement
  • reference the date/ID in original report
  • user is made aware of the revision
  • revised record shows time/date of change and name of person responsible for the change
  • retain records
34
Q

how can you minimise transcriptional errors in the lab

A
  • have two independent checkers
  • delta checks
  • cannot authorise /time interval
  • automation not manual
  • bidirectional interfacing softward
  • clear worklists
  • manual transcription in a quiet place
35
Q

What is a CRM and reference material?

A

reference material- homogeneous and stable >1 properties established to be fit for intended use in measurement process

CRM- ref material characterised by metrologically valid procedure w certificate provides

  • value of specificed property
  • assoc uncertainy and - statement of traceability
  • WHO ref material; multi centre international collaborative study rep assay methods, types of lab, countries
36
Q

How can spectral overlap be compensated for in flow cytometry?

A

single stained controls to account for spillover

  • compensation control as least as bright as stained sample
  • neg/pos pop matched autofluorescence
  • fluorochrome used for control must match one used for experiment
  • use bright fluorochrome for dim antigen

Unstained controls for autofluorescne

Automated softward adjust and calculate spectral overlap
Online program to design panels

37
Q

When a new antibody is introduced what do you have to do to see if they are fit for purpose?

A

1) check conc antibody, dilution studie to optimise , use lowest volume with good sensitivity and separation from neg pop
2) run in parellel specificity
3) single stained controls for compensation again
4) run as a panel with other markers
5) Document

RCPA Immunopathology Part 2 (19 decks)

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