FAQ about IQC

Why internal quality control, IQC, is important?

The IQC, internal quality control, aims to safeguard consumers from harm, making quality control crucial in various high-standard industries, such as pharmaceuticals, automobiles, aviation, food and beverages, delivery services, electronics, and medical devices, including In-Vitro Diagnostics (IVD). A single mistake can result in severe consequences for the consumer, even life-threatening situations. In the clinical laboratory, imprecision can significantly affect clinical decisions. Good quality is invisible, but the bad quality is difficult to overlook.

What is internal quality control, IQC, material?

In the clinical laboratory, Internal Quality Control (IQC) material mimics patient samples and contains multiple parameters for testing. Control materials (usually liquid controls) are used to monitor the test system and verify that quality patient test results have been attained. It can be pre-assayed or unassayed, with or without value ranges for each parameter. Assayed material is supplied with value ranges for each parameter included in this specific IQC material. For material supplied without value ranges for each parameter, the laboratory needs to establish its own QC reference ranges. IQC material can be a third-party quality control or a ‘System Supplier Control’ and then be part of the clinical chemistry system including calibrators, QC, instruments, reagents, and consumables from a complete integrated system. IQC should be run regularly as part of the daily workflow and at any time when something may have compromised the analytical quality.

What is internal quality control testing, IQC testing?

The clinical testing laboratory is responsible for ensuring and enhancing analytical quality to avoid significant impacts on clinical decisions due to imprecision. IQC testing, treating control materials like patient samples, is a routine part of the analytical process from sample placement to result generation. By comparing IQC results with established reference ranges and using QC statistical rules, the laboratory gains insights into accuracy and precision, helping to accept or reject patient results. IQC performance goals detect critical shifts in performance, preventing erroneous results and patient harm.

What are the benefits of investing in the IQC and analytical quality?

  • IQC testing is an investment that will enable the laboratory to detect a failure in analytical quality.
  • An unacceptable level of medically unreliable results leads to significant unbudgeted costs (internal and/or external failure), followed by patient inconvenience and stress, delays in treatment, or damage to the reputation of the laboratory.
  • Investing in the laboratory’s analytical quality at the optimum level will significantly reduce unexpected costs of corrective action.

What are some best practices for IQC?

The first essential step in setting up internal quality control (IQC) of a test procedure in the clinical laboratory is to select the proper IQC procedure to implement. This includes choosing the statistical criteria or control rules, and the number of control measurements, according to the quality required for the test and the observed performance of the method. Then the right IQC procedure must be properly implemented.

What are some common statistical criteria or control rules?

Multirule QC uses a combination of decision criteria, or control rules, to decide whether an analytical run is in-control or out-of-control. The well-known Westgard multirule QC procedure uses 5 different control rules to judge the acceptability of an analytical run.

How to troubleshoot an IQC rule violation?

​When an error is detected in IQC e.g., there’s a critical shift in performance or any of the IQC rules are violated, the following step is troubleshooting. A practical way is to establish a checklist to identify the root cause of the IQC issue.

  1. Analyzer – are there any instrument flags or error messages visible?
  2. Review QC chart
    1. Are there any QC trends?
    2. Is there a one-off result visible?
    3. Is it a systematic or random error?
  3. Review the QC chart of other analytes
    1. Is the QC error isolated to a single chemistry assay?
    2. Or are there multiple chemistries affected?
  4. Instrument maintenance – is the instrument maintenance up to date and performed according to the guidelines?
  5. Last acceptable QC result
    1. What may have occurred since the last acceptable QC result?
    2. Has anything changed (calibrator, reagent..)?
  6. QC material – is QC material:
    1. Satisfactory?
    2. Possibly out of date?
    3. Reconstituted vial expired?
    4. Specific analyte shelf life past?
  7. Other issues – are there possibly any other instrument issues?
  8. Record all the details, corrective actions, and changes in the process.
  9. Rerun QC

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