Podcast
Questions and Answers
Which of the following best describes the CAP definition of assay verification?
Which of the following best describes the CAP definition of assay verification?
What is the main purpose of assay verification in a laboratory setting?
What is the main purpose of assay verification in a laboratory setting?
Which performance characteristic is NOT required for verifying unmodified FDA-approved tests?
Which performance characteristic is NOT required for verifying unmodified FDA-approved tests?
What is the implication of a test being labeled 'for in vitro diagnostic use'?
What is the implication of a test being labeled 'for in vitro diagnostic use'?
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Which of the following is included in the data laboratories must obtain for assay verification?
Which of the following is included in the data laboratories must obtain for assay verification?
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What is the primary goal of method validation in a molecular diagnostics laboratory?
What is the primary goal of method validation in a molecular diagnostics laboratory?
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Which of the following describes the challenge in validating molecular diagnostics compared to clinical chemistry?
Which of the following describes the challenge in validating molecular diagnostics compared to clinical chemistry?
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Which organizations require laboratories to validate the performance of tests before reporting results?
Which organizations require laboratories to validate the performance of tests before reporting results?
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What is the WHO definition of assay validation?
What is the WHO definition of assay validation?
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What is provided as a practical reference to aid the validation process in molecular diagnostics laboratories?
What is provided as a practical reference to aid the validation process in molecular diagnostics laboratories?
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What is the FDA's definition of assay validation?
What is the FDA's definition of assay validation?
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Which of the following committees guided the update to the 2009 AMP Molecular Diagnostic Assay Validation White Paper?
Which of the following committees guided the update to the 2009 AMP Molecular Diagnostic Assay Validation White Paper?
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Which statement accurately reflects the standard of practice in assay validation according to this document?
Which statement accurately reflects the standard of practice in assay validation according to this document?
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What is the formula to calculate sensitivity?
What is the formula to calculate sensitivity?
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What term describes the lowest concentration of analyte that an assay can consistently detect?
What term describes the lowest concentration of analyte that an assay can consistently detect?
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Which of the following is NOT a source of contamination that can affect analytical specificity?
Which of the following is NOT a source of contamination that can affect analytical specificity?
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How is analytical specificity defined?
How is analytical specificity defined?
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Why are reference materials (RM) important in assay validation?
Why are reference materials (RM) important in assay validation?
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Which type of substances should be ruled out through interference studies during validation?
Which type of substances should be ruled out through interference studies during validation?
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Which of the following is a potential drawback when using reference materials?
Which of the following is a potential drawback when using reference materials?
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Which factor is essential to evaluate regarding each assay when selecting reference materials?
Which factor is essential to evaluate regarding each assay when selecting reference materials?
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Which of the following is NOT a required performance characteristic for modified FDA-approved or non-FDA cleared tests?
Which of the following is NOT a required performance characteristic for modified FDA-approved or non-FDA cleared tests?
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What is the main purpose of establishing reference intervals for a laboratory patient population?
What is the main purpose of establishing reference intervals for a laboratory patient population?
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What specifically assesses the clinical validity and clinical utility of a test?
What specifically assesses the clinical validity and clinical utility of a test?
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Which of the following best describes the role of specimen stability in assay performance?
Which of the following best describes the role of specimen stability in assay performance?
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When designing a molecular diagnostic assay, which of the following steps is necessary?
When designing a molecular diagnostic assay, which of the following steps is necessary?
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Which of the following parameters may be necessary for genotyping assays?
Which of the following parameters may be necessary for genotyping assays?
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What is an essential aspect to consider when establishing minimal acceptance performance criteria?
What is an essential aspect to consider when establishing minimal acceptance performance criteria?
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What is the purpose of reviewing literature in assay design?
What is the purpose of reviewing literature in assay design?
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What is clinical sensitivity?
What is clinical sensitivity?
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In terms of clinical utility, what must be clearly defined?
In terms of clinical utility, what must be clearly defined?
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What does clinical specificity measure?
What does clinical specificity measure?
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What is the formula used to calculate negative predictive value?
What is the formula used to calculate negative predictive value?
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Which person is responsible for ensuring clinical utility in a laboratory?
Which person is responsible for ensuring clinical utility in a laboratory?
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How is clinical validity defined?
How is clinical validity defined?
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What factors influence predictive values?
What factors influence predictive values?
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What is the primary purpose of analytical validation?
What is the primary purpose of analytical validation?
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Study Notes
Molecular Diagnostics Assay Validation
- Molecular diagnostics laboratories must validate tests before reporting patient results
- The goal of validation is to ensure that a test is ready for implementation in the clinical laboratory
- This process is challenging for low-volume, labor-intensive tests which are common in molecular diagnostics
Definitions
- Assay Validation is the process of proving that a procedure, process, system, equipment, or method works as expected
- Assay Verification is an abbreviated process to demonstrate that a test performs in substantial compliance to previously established claims
Assay Types
- Unmodified FDA-Approved or Cleared Tests must be verified to perform as expected, obtaining data on accuracy, precision, reportable range, linear range (for quantitative assays), and reference intervals
- Modified FDA-Approved or non-FDA Cleared Tests (e.g., Laboratory Developed Procedures - LDPs) must establish the following performance characteristics: accuracy, precision, reportable range, linear range, reference intervals, analytic sensitivity, and analytic specificity
Assay Design
- Define the requirements of a test, including intended use, test method, and expected performance characteristics
- Review the literature to support evidence for clinical utility and clinical validity of the test
- Assess the clinical indication for the test, define the target population, and define the purpose of the test (e.g., screening, diagnosis, prognosis, monitoring)
- Choose pertinent specimen types and establish criteria for sample rejection
- Establish minimum acceptance performance criteria
- Consider the role of test results in patient management and assess technical feasibility of assay implementation
- Choose appropriate controls and perform initial optimization studies to establish assay protocol and parameters before starting validation
Clinical Validation
- Clinical validation assesses the clinical validity and clinical utility of a test in light of clinical characteristics of the disease/marker being tested
- Data for clinical validation can be obtained from studies by the laboratory, peer-reviewed literature, or other reliable sources
- Clinical validation consists of:
- Clinical Validity: the ability of a test to detect or predict the associated disorder (phenotype)
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Clinical Utility: the usefulness of the test in the diagnosis or treatment of patients
- Must define testing purpose (screening, diagnostic, predictive, etc.)
- Documented via literature review and/or independent establishment by the laboratory
- Clinical Sensitivity: the proportion of patients with the mutation/disease who have a positive test result (TP ÷ (TP + FN))
- Clinical Specificity: the proportion of patients who lack the mutation/disease who have a negative test result (TN ÷ (FP + TN))
- Predictive values are a function of the prevalence of the disease in the population being tested as well as the properties of the test (e.g., the higher the prevalence, the higher the likelihood that a positive result is a true positive)
Analytical Validation
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Analytical Sensitivity: the ability of a test to detect the analyte of interest at its lower limit of detection (LLOD)
- The lowest concentration of analyte that the assay can consistently detect with acceptable precision
- The lowest amount of starting material for an assay to provide consistent results within precision
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Analytical Specificity: the ability of a test to give a normal (negative) result in specimens that do not have the mutation being tested (TN ÷ (TN + FP))
- Also referred to as the ability to detect only the intended analyte without cross-reacting with related analytes or potentially interfering substances
- Potential sources of interference include poor sampling, specimen contamination, cross contamination, inclusion of normal tissues, tissue from source addition, bacteria, endogenous substances, and exogenous substances
- Potential interfering substances and cross-reacting nucleic acids that could affect the measurement of the nucleic acid of interest should be ruled-out during validation
Reference Materials and Controls
- Reference materials (RM) are substances with homogenous and well-established properties used for calibration, assessment of methods, assigning values to materials, or quality control
- RM should be selected based on the needs of the assay, methodology, and availability of materials
- Potential benefits and drawbacks of RM should be evaluated for each assay
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Description
This quiz covers the essential principles of assay validation in molecular diagnostics laboratories. You will learn about the validation process necessary for implementing tests in clinical settings, as well as the differences between assay validation and verification. Additionally, it discusses the requirements for various types of assays, including FDA-approved tests and laboratory-developed procedures.
