People are often confused about the difference between Quality Assurance (QA) and Quality Control (QC) testing and although they are related in some ways they are entirely different concepts.
In the world of medical testing performing a Quality Control (or QC) test means assessing a measurement systems performance using predefined standards. The aim is to gain confidence that analytical results are consistent, comparable, accurate and within the specified limits of precision.
Quality control material may have special requirements for sample handling and preparation
so package inserts should always be consulted prior to undertaking a test. Accredited laboratories in Australia who undertake Point of Care Testing (PoCT) must comply with requirements from NATA, which draw from the Australian Association of Clinical Biochemists (AABC) position statement, recommending that point of care systems be subject to QC testing:
- With every new delivery of reagents
- Before starting a new batch of tests
- At a minimum of once per month
There are also occasions when QC should be run on an ad-hoc basis and this may be typically performed when a result or the performance of an instrument or tests is in question, or when required as part of a troubleshooting or investigative process.
If a QC test result falls outside of the established limits it should, in the first instance, be repeated to confirm the erroneous result, following which further investigation should be undertaken.
In summary undertaking a test using Quality Control (QC) material is a technical exercise that checks the performance of an analyser against pre-defined criteria (e.g. target ranges), in order to assess the bias and precision associated with sample results. Generally QC material is available in the form on an artificial sample which is tested in a similar way to a patient sample and is a useful tool in times of uncertainty. However it does not necessarily provide a ‘holistic’ approach, which can leave sources of discrepancy remaining unidentified. Quality Assurance Programs (QAP) aim to fill this gap.
Quality Assurance is best defined as a set of activities designed to ensure that a process (e.g. undertaking lab tests) meets its quality goals. In other words, it is a method of testing the proficiency of facility to manage the quality of it’s work and analytical results.
Quality Assurance Programs
The principle of a Quality Assurance Program (QAP) is to assess the proficiency of test and operational procedures using a workflow that mimics, as closely as possible, normal patient testing. At a basic level participating in QAP involves testing a sample of known concentration and comparing your results against a reference laboratory, just like a lab comparison. In reality however QAP is much more than just that.
A Quality Assurance Program (QAP) is an externally administered policy of integrated management activities, which is designed to provide an ongoing method by which the whole system (i.e. user, equipment and reporting protocols) may be monitored. Such programs aim to ensure that the instrumentation meets and performs in a manner expected by the operators and the laboratory operates in a manner expected by clients. Typically the requisite activities may be divided into 3 main phases, as follows:
- Pre-analytical (planning and preparation)
- Analytical (undertaking quality control tests)
- Post-analytical (reporting results, assessment and data review)
The overall aim is to evaluate the effectiveness of procedures surrounding the operation of an instrument and identify any problems in order to ensure that accurate performance and prompt reporting of tests is maintained.
For laboratories accredited to the ISO 15189 standard for medical testing all tests on offer should be enrolled in external Quality Assurance Programs (QAP).
The external Quality Assurance Programs most Australian laboratories participate in are administered by the Royal College of Pathologists Australasia Quality Assurance Programs (RCPA QAP) and are designed to assess the adequacy of processes such as:
- Receiving a delivery
- Following procedure and instructions
- Testing in a timely fashion
- Correct use of analysers
- Competence reporting results
- Interpretation of results
- Analysis of reports
When performing QAP testing it is important to follow the guidelines and instructions on sample handling, treatment and preparation and undertake testing in a timely fashion (before to the due date).
Following the submission of results to the organisation they assign target ranges and produce reports which provide an overview of your ongoing performance. These reports are a powerful tool used in troubleshooting potential issue as they provide ongoing precision and accuracy data, and also a visualisation of results against your peer group (others using the same tests / methods / analysers).
The nature of the report produced by the RCPA QAP is such that the (de-identified) results from all analysers of the same type registered on the program are visible, with the participants (your lab’s) specific results highlighted for review. This allows the individual results to be compared to the performance (precision) of the whole group. In this way any undesirable deviations are immediately apparent and, with the report aiding to identify their cause, appropriate remedial action may be taken in order to maintain confidence in the testing process