What is Calibration Verification & why is it so important?
What is Calibration Verification or Linearity?
Calibration Verification, or Linearity assessment, is becoming a fundamental element for laboratories in the USA who have access to instrumentation used in the running of patient samples.
Linearity is the ability to provide results that are directly proportional to the concentration of the analyte in the test sample. CLIA defines this as the assaying of materials of known concentrations in the same manner as a patient sample to verify the instruments linearity throughout the reportable range. By performing calibration verification a lab is assessing if their test system’s calibration is still valid and if their chosen method is linear across the full reportable range, it will also supplement their existing QC and EQA/PT by challenging a larger segment of the AMR (Analytical Measuring Range). According to CLIA, a laboratory should perform, and document, calibration verification procedures at least once every 6 months or whenever one of a number of other factors occur, for example, a complete change of reagents, major preventative maintenance or replacement of parts, new instrument validation or when their control material is highlighting unusual shifts or trends in performance.
It is commonplace for laboratories to confuse calibration verification and reportable range, so much so, that advice and guidance is continually being asked for by laboratories. In short, reportable range is one of the first characteristics that should be used as an evaluation tool whereas calibration verification should be viewed as a continual performance check.
How it works
Aside from carrying out testing twice per year, CLIA also recommend that a minimum of 3 levels are tested (although most laboratories prefer to test 5) covering the low end, mid-point and high end of the instruments reportable range. Labs should run at least 2 replicates of each level in the same way they would a patient or control sample. The results are then plotted against the target values provided, if the results obtained are within the pre-established limits then the performance is considered acceptable. The degree to which the plotted curve conforms to a straight line is a measure of system linearity.
In many cases, data reduction software is provided with the product and this can be used to automatically plot results. This software is also capable of comparing results to peer group data for troubleshooting purposes.
Our Acusera Linearity Sets and Verify data reduction software will provide laboratories the chance to test low, medium and high ranges on their instrumentation – in doing so, labs will keep in line with CLIA recommended bi-annual testing as well as ensuring their instrumentation is performing well across the full reportable range.
Designed with convenience in mind, our sets cover a wide range of clinical testing including; Cardiac Markers, Therapeutic Drugs and Specific Proteins in a liquid ready-to-use format. The varying levels and combination of unique analytes enables laboratories to consolidate testing and reduce the number of individual products required.
Complementing our Linearity sets is our data reduction software, Acusera Verify. When used in conjunction with our sets you can effectively challenge your instrument across the full reportable range while ensuring accurate and reliable patient testing. Some features of our software include easy to interpret charts for at-a-glance performance, access to real-time peer group data to enhance troubleshooting and an intuitive user interface for simple data entry.