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.
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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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The Acusera range of true third party controls boasts an impressive range of benefits ultimately designed to help laboratories reduce costs and time while also ensuring an accurate and reliable test system.
The extended shelf life of our controls allows the same lot of control to be used for a period of up to 2 years keeping costly new lot validation studies to a minimum. We may also be able to sequester lots on your behalf.
The availability of commutable controls designed to react to the test system in the same manner as a patient sample and controls targeted at clinical decision levels will not only help you to meet ISO 15189:2012 requirements but will effectively challenge instrument performance.
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An important consideration when choosing your Quality Control material that is often overlooked is the shelf life of the control. With every new lot of control extensive validation studies must be performed. Regulatory bodies such as CLIA require new lot numbers to be evaluated before routine use in the laboratory. For example, CLIA has instructed that any new control lot to be run alongside patient samples will need to be verified alongside the old lot of control. The process is designed to give laboratory professionals confidence in the new material and ensure it is fit for purpose before implementing it in the lab.
As part of the validation process laboratories are required to assay both the old and new lots side by side. The current lot is then used to help verify if the new lot will be acceptable to run within the lab. Such validation studies can be very costly for a lab as well as being extremely time consuming – with some studies taking up to a month to complete! By choosing a control with a longer shelf life laboratories can aim to use the same lot of control for a longer time period. Ultimately this means fewer lot changes and minimal inconvenience for the lab. With a shelf life of 2 years for liquid controls and up to 4 years for lyophilised, coupled with unrivalled stability claims, employing Randox Quality Control in your laboratory will ensure that expensive lot changes will be a thing of the past. Our comprehensive control offering is guaranteed to increase efficiency and reduce costs in any laboratory without compromising on quality.
Contact us today to find out more information on our Acusera range of Quality Controls.