QA is the sum of all those activities in which the laboratory is engaged to ensure that information generated by laboratory is correct.

1
Introduction
Quality Assurance in Hematology

• QA is the sum of all those activities in which
  the laboratory is engaged to ensure that
  information generated by laboratory is correct.
• QA includes all aspects of laboratory activities
  that affects the results produced, from the
  choice of methods, to the education of personnel,
  to the handling of specimens and reporting
  results.
• The real purpose of QA activities is to determine
  how correct or incorrect the results emanating
  from the lab are, and to allow those managing the
  lab to determine whether or not the lab is
  fulfilling its functions satisfactorily.

• 3 major activities of QA
• 1 ) Preventive those activities that are done
  prior to the examination of the specimen or
  sample and that are intended to establish systems
  conducive to accuracy testing ( eg preventive
  maintenance and calibration of instruments,
  testing of media, orientation and training of
  personnel )

2 ) Assessment those activities that are done
during testing to determine whether the test
systems are performing correctly ( eg the use
of standard and controls, maintenance of control
charts ) 3 ) Corrective those activities that
are done, when error is detected, to correct the
system ( eg equipment troubleshooting,
recalibration of instruments )
QA in Haematology Laboratory

• QA in haematology lab is intended to ensure the
  reliability of the lab tests.
• The objective is to achieve precision and
  accuracy
• 4 components of QA programme
• 1 ) Internal Quality Control ( IQC )
• 2 ) External Quality Control ( EQC )

• Accuracy
• - the closeness of the estimated value to the
  true mean
• - can be checked by the use of reference
  materials which have been assayed by independent
  methods of known precision
• Precision
• - reproducibility of a results, whether accurate
  or inaccurate within a define frame time ( eg
  within the same day, from week to week etc )
• - can be controlled by replicate tests, check
  tests on previously measured specimens and
  statistical evaluation of results

Internal Quality Control ( IQC )

• based on monitoring the haematology tests
  procedures that are performed in the lab
• includes measurements on CONTROLS is intended
  to ensure that there is continual evaluation of
  the reliability of the work of the lab and that
  control is exercised over the release of the
  results

External Quality Control ( EQC )

• is the objective evaluation by an outside agency
  of the performance by a number of laboratories on
  material which is supplied specially for the
  purpose
• is usually organized on a national or regional
  basis
• analysis of performance is retrospective
• the objective is to achieve comparability with
  results of other labs.

2
Statistics of QC
Control materials

• Specially prepared
• It may be anticoagulated WB, preserved pooled red
  cells, plasma or serum
• It can be used to check for accuracy if the value
  has been reliably determined ( eg reference
  centre )
• Should have controls of high, normal and low
  values
• At least 1 control specimen should be used for
  every batch
• If large specimens, use 1 control for every 20
  specimens
• The same material is used for EQC or also as
  calibrator

• Mean ( x ) the total score of all the
  measurements divided by the number of
  measurements
• Standard deviation ( SD ) variation in
  measurement obtained in lab tests
• formula SD S ( x x )2
• n 1
• n number of measurement
• Coefficient of variation ( CV ) relation of SD
  to the actual measurement
• formula CV SD X 100
  
• x

Analysis of data

• Standard deviation of control specimens
• if value assigned to a specimen a number of
  times, dispersion of results around the mean will
  indicate the error of reproducibility
• 95 of results on the same specimen should be
  within 2 SD and 99.7 within 3 SD
• by chance, 1 in 20 of measurement might expected
  to fall outside 2 SD and only 1 in 333 outside 3
  SD
• If measurement more widely dispersed, this
  indicates an error in the test

• Control Charts
• originally described by Shewhart, 1st applied in
  clinical chemistry by Levey and Jennings
• Samples of the control specimen are included in
  every batch of patients specimens and the
  results checked on a control chart
• To check precision, it is not necessary to know
  the exact value of the control specimen
• Value has been determined reliably by a reference
  method, the same material can be used to check
  accuracy or to calibrate an instrument
• If possible, controls with high, low and normal
  values should be used
• Advisable to use at least one control sample per
  batch even if the batch is very small
• The results obtained with the control samples can
  be plotted on a chart

3
External QC

• Duplicate Tests On Patients specimens
• provides another way of checking the precision of
  routine work
• Test 10 consecutive specimens in duplicate under
  careful conditions
• Calculate the differences between the pairs of
  results and derive the SD
• Subsequent duplicate tests should not differ from
  each other by more than 2 SD
• This methods will detect random errors but it is
  not sensitive to gradual drift nor will it detect
  incorrect calibration
• Impractical for routine blood counts in a busy
  lab
• A few consecutive specimens in a batch should be
  tested from time to time as a rough check

Internal QC

• Intended to monitor various aspects of test
  performance which performed in the lab
• Measurement on specially prepared materials,
• repeated measurements on routine specimens as
  well as statistical analysis, day by day, of data
  obtained from the routine tests which have been
  carried out in the lab
• Measures provide a way to achieve precision

• The major purpose to achieve harmonization
  concordance between labs
• The principle is that the same material is sent
  from a national or regional centre to a large
  number of laboratories
• All the labs send the results back to the centre
  where they are analysed and interpreted by one of
  several procedures
• From the results returned from the participants,
  the median or mean and SD are calculated
• An individual lab can then compare its
  performance in the survey with that of other labs
  and with its own previous performance ( using
  deviation index )

• A deviation index ( score )
• actual results weighted median / mean for test
• weighted SD
• Interpretation
• 0.5 excellent
• 0.5-1.0 satisfactory
• 1.0- 2.0 acceptable
• gt 2.0 defect requiring attention

• Organizations
• A ) National External Quality Assurance
• Programme ( NEQAP )
• Pusat Darah Negara
• B ) Royal Collage of Pathologists of
• Australia ( RCPA )
• C ) International EQA Scheme for
• Haematology ( IEQAS )