Mythbusting: ‘Using IQC and EQA From the Same Provider Leads to QC Bias’
Some laboratory professionals believe that using Internal Quality Control (IQC) and External Quality Assurance (EQA, also known as Proficiency Testing) material from the same provider can lead to increased levels of qc bias, or that their test system will not be appropriately challenged. It is important to address these concerns, because some labs may in fact be hindering their own performance by using IQC and EQA material from different sources.
It is important to first understand how IQC and EQA work together to help form a complete Laboratory Quality Management System.
IQC and EQA in Laboratory Quality Management
IQC is a means of monitoring test system precision on a daily basis. IQC effectively evaluates test system performance over time, so that any sudden or gradual shifts in performance can be detected. However, while IQC is an effective performance monitor, it cannot detect more intricate problems like calibration errors or wide acceptable limits provided by some QC manufacturers.
EQA is essential for challenging test system accuracy, and is carried out less frequently than IQC testing. EQA samples are tested ‘blind’ and the results are returned to the scheme organiser. As EQA testing compares an individual lab’s performance to other labs using the same method and instrument, it is a very effective tool for identification of potential issues.
Is there any disadvantage to using IQC and EQA material from the same provider?
The answer to this question depends primarily on the source material of the IQC and EQA. If an IQC provider manufactures their material using artificial additives or components of animal origin, then it will not be suitable to use EQA material from the same provider. Westgard (2011) maintains that using non-commutable IQC or EQA material can lead to results becoming compromised due to matrix effects – something which would not happen using commutable controls.
For example, with Immunoassay testing, non-human components of IQC material interact with antibodies in the reagent in a different way to fully human patient samples – ultimately giving unpredictable shifts, and not adhering to the ISO 15189 requirement to: “use quality control materials that react to the examining system in a manner as close as possible to patient samples”.
However, if the IQC and EQA material is manufactured using a source material which is similar in composition to patient samples (100% human), this commutable control will adequately mimic patient sample performance; meaning labs can use EQA and IQC material from the same provider with confidence that the integrity of their results is maintained.
ISO 15189 also states: “Use of independent third party control materials should be considered…”. In this instance, ‘Independent’ does not mean from a separate provider. It means that the QC material should not be optimized for use on one specific instrument (i.e. not dependent on a single instrument/method type).
No regulatory body states a requirement to use different providers for IQC and EQA material. Indeed, using IQC from one provider and EQA from another provider could increase the risk of labs using non-commutable material.
Labs should use commutable IQC and EQA material for a true assessment of their test system. Randox QC and RIQAS EQA are specifically designed with commutability in mind, giving labs a control which reflects patient sample performance and ensures excellent performance.
How can we help?
To learn how Randox can offer a complete solution for your laboratory, follow the links below or submit a question using the form above.
Westgard, S. (2011). Is QC Quality Compromised?. Available: https://www.westgard.com/qc-quality-compromised.htm. Last accessed 31st October 2017.
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Did you know that Randox is the company behind the RIQAS EQA scheme? RIQAS (Randox International Quality Assessment Scheme) is just one area of our comprehensive Quality Control portfolio. As such it is our resolution this New Year to introduce Randox as the brains behind RIQAS and show you that we are more than just an EQA provider by sharing our passion for laboratory QC.
Who are Randox Quality Control?
At Randox we believe in producing high quality material that can help streamline procedures, whilst saving time and money for laboratories of all sizes and budgets. With our extensive product offering comprising third party QC sera, interlaboratory data management software and calibration verification products, you can be sure that our complete QC solutions will provide you with a comprehensive overview of laboratory performance.
Seeing the complete picture with Randox QC
As one of the largest manufacturers of true third party, commutable controls we deliver high quality, cost effective quality control solutions designed to accurately assess instrument performance and provide confidence in patient test results.
Acusera 24.7 enables you to drive for more accurate results by helping you to monitor and interpret QC data. With access to an impressive range of features, including the automatic calculation of Measurement Uncertainty, Total Error and Sigma Metrics, Acusera 24.7 ensures analytical quality.
RIQAS is employed by more than 45,000 laboratory participants in 124 countries. With frequent reporting you will identify errors sooner ultimately reducing the need to carry out preventable, expensive retests on a large volume of patient samples.
The Acusera linearity sets cover a wide range of clinical testing including; cardiac markers, therapeutic drugs and proteins. Designed with convenience in mind, the range ultimately helps you to meet CLIA requirements for calibration verification and the assessment of linearity.
Beyond selling laboratory QC we are also passionate about education, offering a range of educational guides, seminars and webinars, with more to come throughout 2017. Check out our QC resources hub for our current educational material and let us know what educational material you would like to see.
For more information, or to request a visit from one of our QC Consultants, contact us via firstname.lastname@example.org.
We are delighted to announce the launch of Acusera 24.7 Live Online Version 1.6, now featuring automatic calculation of Measurement of Uncertainty, Total Error and Sigma Metrics.
The new Uncertainty of Measurement report automatically generates and displays the Measurement Uncertainty (UM) of all QC tests currently in use helping you to easily meet ISO 15189:2012 requirements.
To calculate UM, users must first enter the SEM of their intra assay precision (A) for each individual test and each level of control. This is based on a minimum of 20 replicates performed within the same run. Based on performance history, the Acusera 24.7 software will then automatically calculate the SD of the inter assay precision (B). The software then uses the following formula to automatically calculate the UM.
Since UM is calculated using SD and one SD is equal to 68% confidence on the Gaussian curve the software multiplies the UM by 1.96 to attain the Expanded UM and a confidence level of 95%.
The report can be filtered by date to display data from a specific date range and may also be exported to CSV or printed.
The Statistical Metrics Report facilitates enhanced performance assessment by incorporating several new metrics including; Measurement Uncertainty, Total Error (TE) and Sigma.
%Bias provides an indication of your laboratories performance compared to the peer group mean, while TE gives an indication of the overall error within a test system taking into account both imprecision and inaccuracy (bias). The availability of a Sigma Metric for each test is useful for designing an appropriate QC strategy. For example methods with a high Sigma score generally require less stringent QC strategies than those with a low Sigma value.
- TEa – Total Allowable Error
- %Bias – Deviation from the target
- %CV – Imprecision of the data