People and pets can suffer unnecessarily prolonged illness and fatal consequences as a result of poor-quality results produced by laboratory analysers.
Did you know that in a reference laboratory, for human or animal samples, all test results have to be signed off before they are released to the clinician?
As part of their accreditation (ISO 17025) Reference Laboratory results are required to be routinely checked by Quality Control measures before they are released to the clinician. All results, especially those outside of the test reference ranges will be checked by a member of lab staff in relation to the request, the patient information, the sample quality (volume, haemolysed, icteric, clotted) and the analyser used. Only once this has been done can the report be sent. A strict system of measures is in place to ensure that the results seen by the doctor or vet are accurate and appropriate. These will involve the use of Quality Control material and Quality Assurance measures. Results from any analyser should be regularly checked for Precision (Repeatability) and Accuracy (Comparison to ‘Gold Standard’ Analysers).
When working with in-house instruments, how can we be sure that our results are also correct? Most veterinary practice laboratories are not subject to the requirements of a compulsory Quality Assurance scheme, but we should also expect a high diagnostic standard.
QA & QC?
Quality Assurance (QA) covers everything that a laboratory does to ensure that it is providing correct and accurate results. This will consist of programme of activity with clearly defined processes for running tests including staff training and competency assessments and may utilise external resources for comparison of results from the same sample or analyser. Commercial QA schemes are available via paid services and can provide very comprehensive data on test and individual analyser performance.
Quality Control (QC) in the laboratory includes the use of standard materials, with known results values, to check that a test is working correctly. QC material may have a reference range for measurement in haematology or clinical chemistry – a known number of cells of a particular type or a target value - or may simply give a positive or negative result for a qualitative test. A reference laboratory will be required to perform QC testing daily – and even several times per day depending upon the assay or analyser – to ensure that instrument outputs are accurate. Suppliers of laboratory diagnostic instruments for in-house use will
provide guidance on their recommended frequency of QC processes, and individual practices should consider their own schedule of checks according to their workload.
A requirement?
At the present time, there is no official requirement for veterinary teams to carry out any QC or QA checks at all – in stark contrast to NHS Hospital and Reference Laboratories, which are highly regulated to Government standards.
For practices registered with the Royal College of Veterinary Surgeons’ Practice Standards Scheme for Small Animal, Equine or Farm work, evidence must be provided that QC processes are carried out from the first level of accreditation at Core Standards level up to those with Hospital status. For the additional Laboratory and Clinical Pathology Award, membership of a recognised laboratory External Quality Assurance (EQA) scheme is compulsory.
RCVS PSS Core Standards - All species (9.1.21) [1]:
Requirements: There must be suitable arrangements for quality control of automated practice laboratory tests.
Guidance notes: Periodic controls as per the manufacturer’s instructions to test the machine is running correctly and is calibrated correctly, the results documented and acted upon where necessary.
RCVS PSS GP and Hospital Standards - All species (9.2.3):
Requirements: In addition to internal quality control of automated laboratory tests, external quality assurance, by internal analysis of external samples via a QA scheme or by comparing internal samples to external labs, must be routinely undertaken and the results documented and acted on where necessary.
Guidance notes: EQA is the analysis of samples by reference to an external laboratory performed either by internal analysis of control reagent received from the laboratory through a QA scheme or by comparing samples run internally with the same paired sample run externally. This should also be undertaken for tests carried out using Point of Care (POC) devices.
The Veterinary Hospital Standards for Small Animal work also go on to say that this should also be undertaken for tests carried out on Point of Care (POC) devices, and for any site that wishes to apply for the RCVS Award for their Laboratory and Clinical Pathology service, membership of an External Quality Assurance Scheme (EQAS) is required, and regular sample technique audits should be carried out to rectify avoidable problems.
How and when?
Laboratory instrument and reagent suppliers will provide QC material with known values for their tests. The test is run in the usual way using the QC as your sample, and the results are compared to the reference ranges for that lot.
Alternatively, exactly the same patient sample can be run in-house and also via your reference laboratory, and the results are compared. Some tolerance must be expected when using this option, due to differences in the time after sampling that the test was performed, and the potential for varying testing methods used. However, the results should be in line and checked by a competent member of staff.
The use of an EQAS gives access to a wider pool of resources on test results, and as a regular programme of work it will prompt users to get their tests done! We all know that it’s tempting to put off tasks that seem non-essential on busy days. Highly specific data can be generated and any demonstrated trends across time, different analysers and sites can be easily identified. Any remedial action can be taken in a
timely manner and keep your lab running smoothly. Care should also be taken to ensure that all pre-analytical guidance is followed in relation to sample taking, handling and storage. Time spent on good instrument care is wasted if samples are of poor quality or have been handled badly before testing. Ensuring good quality results from your in-house laboratory is not onerous and can be incorporated into your day-to-day routine. The frequency and depth of QC testing is an individual choice but should become an integral part of good laboratory practice involving instrument cleaning, checks and maintenance and ensuring the best patient care and outcomes.
For more information on effective QC and QA processes contact us enquiries.uk(at)horiba.com or your own laboratory service provider for in-house or reference facilities.
References:
[1] Practice Standards Scheme – Modules and Awards, v.3.2 https://www.rcvs.org.uk/document-library/small-animal-modules/ (Accessed August 2022)
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