Podcast
Questions and Answers
What does Quality Assurance (QA) primarily study?
What does Quality Assurance (QA) primarily study?
Which performance characteristic is NOT concerned with reliability?
Which performance characteristic is NOT concerned with reliability?
Which term describes the agreement between replicate measurements?
Which term describes the agreement between replicate measurements?
What does sensitivity in an assay refer to?
What does sensitivity in an assay refer to?
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What happens to accuracy when precision is poor?
What happens to accuracy when precision is poor?
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Which of the following is an example of a systematic error?
Which of the following is an example of a systematic error?
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What is specificity in the context of an assay?
What is specificity in the context of an assay?
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What is one factor that might impact assay practicability?
What is one factor that might impact assay practicability?
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What is the main reason for requiring standardisation in immunoassays?
What is the main reason for requiring standardisation in immunoassays?
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What does Internal Quality Control (IQC) refer to?
What does Internal Quality Control (IQC) refer to?
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Which of the following describes External Quality Assessment (EQA)?
Which of the following describes External Quality Assessment (EQA)?
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What characteristic is NOT required for a standard used in immunoassays?
What characteristic is NOT required for a standard used in immunoassays?
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Who establishes the International Standard (IS) for immunoassays?
Who establishes the International Standard (IS) for immunoassays?
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What is one of the main goals of quality assurance in laboratory investigations?
What is one of the main goals of quality assurance in laboratory investigations?
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Which of the following is associated with heterogeneity in samples?
Which of the following is associated with heterogeneity in samples?
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Which of these activities does NOT fall under quality assurance?
Which of these activities does NOT fall under quality assurance?
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What is the main purpose of a calibration standard in laboratory assays?
What is the main purpose of a calibration standard in laboratory assays?
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What characterizes the preparation of an International Standard (IS)?
What characterizes the preparation of an International Standard (IS)?
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What was the potency assigned to the first WHO International Standard for anti-SARS-CoV-2 immunoglobulin?
What was the potency assigned to the first WHO International Standard for anti-SARS-CoV-2 immunoglobulin?
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From how many convalescent patients was the first WHO International Standard derived?
From how many convalescent patients was the first WHO International Standard derived?
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What process is used to evaluate stability in the preparation of International Standards?
What process is used to evaluate stability in the preparation of International Standards?
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What are control materials used for in analytical processes?
What are control materials used for in analytical processes?
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When was the second WHO International Standard for anti-SARS-CoV-2 immunoglobulin proposed?
When was the second WHO International Standard for anti-SARS-CoV-2 immunoglobulin proposed?
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What is the role of laboratory standards in immunoassays?
What is the role of laboratory standards in immunoassays?
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Study Notes
Standardisation & Quality Assurance (Part 1)
- Standardisation and quality assurance (QA) are crucial for immunoassays.
- Immunoassays utilize biological materials as standards and require quality control (QC) for accurate quantification of complex analytes.
- Common problems include heterogeneity of analytes in samples and standards. Analytes like proteins and peptides can exist in various forms (post-translational modifications, subunits).
Learning Objectives
- Understand the necessity of standardisation and quality assurance (QA) in immunoassays.
- Identify quality assurance activities.
- Define terms like internal quality control (IQC), external quality control (EQA), international standards, and calibration standards.
- Explore how QA affects assay practicability and reliability.
Why Quality Assurance is Necessary
- Quality assurance encompasses activities that improve quality to ensure reliable laboratory investigations.
- Key activities include performing appropriate tests, preserving samples correctly, and validating/standardising methods.
- Internal quality control (IQC) and external quality assessment (EQA) are also important for ensuring accurate results and correct interpretation.
Definitions
- Internal Quality Control (IQC): A set of procedures for assessing laboratory assays, used to evaluate the reliability of routine assays.
- External Quality Assessment (EQA): A set of procedures for objectively checking laboratory results performed by an external agency.
Standardisation Principles
- Heterogeneity: The different forms of an analyte in samples and standards can cause discrepancies in the results.
- Suitable for use: Standards must be suitable for use across different assay systems with consistent concentration units and stability.
- Continuity: Standards should ensure continuous use over time and across different laboratories.
- Matrix identity: The standard matrix should match the sample matrix to ensure accurate results.
Standardisation in Immunoassay
- International Standards (IS): Created by the Expert Committee on Biological Standardisation (ECBS) of the World Health Organization (WHO).
- Preparation: Typically prepared by the National Institute for Biological Standards and Control (NIBSC) based on international collaborative studies.
- Content: Contain a specific amount of analyte for assay kit and laboratory standard calibration.
- Calibration Standards: Derived from International Standards (IS), used as comparators to determine concentrations in test samples.
Preparation of International Standards (IS)
- Characterisation: IS are characterised using physio-chemical methods.
- Batch size: Prepared in batches (500-5000 ampoules).
- Stability: Stability assessed through accelerated thermal degradation studies.
- Concentration: Concentration measured by direct comparison with existing IS in collaborative studies.
- Statistical analysis and unit assignment: Accepted by ECBS and assigned a unit.
Standardisation: SARS-CoV-2 serology
- Various SARS-CoV-2 serological assays are commercially available.
- WHO developed an International Standard for the anti-SARS-CoV-2 immunoglobulin in 2020.
- The standard was assigned a potency of 250 binding antibody units (BAU).
- Further standards and harmonisation have been developed since 2020.
Standardisation in Immunoassay (Laboratory Standard, Control Material, Reference Material)
- Laboratory standard: Used in an individual lab and calibrated against an International Standard.
- Control material: A preparation used to check the precision and accuracy of analytical processes.
- Reference material: A term often applied to standards and control materials.
Immunoassay Calibration (Diagram)
- The diagram shows the tiered standards used for calibration, from primary standards to working standards. This is followed by method validation, equipment calibration and system performance checks.
Quality Assurance (QA)
- QA is the study of errors and the procedures used to recognise and minimise them in laboratory settings.
- The quality control method selection depends on; method of analysis, performance characteristics.
- Performance characteristics are grouped into practicing and reliability concerns.
Assay Practicability
- Factors considered include speed, cost, safety, and required analytical skills.
- Accurate and precise methods might be slower or require expensive equipment and skilled staff.
Assay Reliability
- Precision: The agreement between replicate measurements, indicating variability due to random error.
- Accuracy: The agreement between the best estimate of a quantity and its true value, assessed from a mean value, influenced by systematic error.
- Method with systematic error: Shows bias (positive or negative bias).
- Specificity: The method's ability to detect only the intended component.
- Sensitivity - Limit of Quantitation (LOQ): The ability to detect small amounts of a substance. It's calculated as the concentration that produces a measurable response above background noise (mean ± 3 standard deviations).
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Description
This quiz focuses on the importance of standardisation and quality assurance (QA) in immunoassays. Participants will explore key concepts such as internal and external quality control, the significance of international standards, and the practical impact of QA on assay reliability. Gain a deeper understanding of how QA influences laboratory investigations.
