Diagnostic Sensitivity vs. Specificity Quiz
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Questions and Answers

What does diagnostic sensitivity measure?

  • The ability to detect individuals without the disease
  • The accuracy of differentiating all cases
  • The ability to generate true-positive results (correct)
  • The proportion of false-positive results

    • Why is high sensitivity important for screening tests?

  • To ensure that no case is missed (correct)
  • To reduce the number of false positives
  • To confirm the diagnosis of the disease
  • To provide a higher accuracy rate

    • What does diagnostic specificity indicate?

  • The total number of tests conducted
  • The ability to detect true-negative results (correct)
  • The proportion of individuals with the disease
  • The effectiveness of confirming a diagnosis

    • In diagnostic accuracy, what represents true positives (TP)?

    <p>Cases correctly identified as patients</p> Signup and view all the answers

    What is the formula used to calculate sensitivity?

    <p>$TP / (TP + FN) x 100$</p> Signup and view all the answers

    What does a test with 100% specificity indicate?

    <p>It is negative for all healthy individuals</p> Signup and view all the answers

    Which parameter indicates the number of cases incorrectly identified as patients?

    <p>False Positive (FP)</p> Signup and view all the answers

    What does the accuracy of a diagnostic method depend on?

    <p>The balance of true positives and true negatives</p> Signup and view all the answers

    Which type of tests require high specificity?

    <p>Confirmatory tests</p> Signup and view all the answers

    What does a receiver operator characteristic (ROC) curve compare?

    <p>Accuracy of two different tests</p> Signup and view all the answers

    What is the primary purpose of intralab quality control?

    <p>To ensure daily monitoring of analytical accuracy and precision</p> Signup and view all the answers

    How are initial control limits established in quality control?

    <p>By analyzing pool material in 20 consecutive runs</p> Signup and view all the answers

    What indicates that an analytical result cannot be reported?

    <p>If the result has been declared 'out of control'</p> Signup and view all the answers

    What is the benefit of using blind control samples in internal QC testing?

    <p>To prevent bias during the analysis process</p> Signup and view all the answers

    Which statement about systematic and random errors during quality control is true?

    <p>Internal QC detects both random and systematic errors</p> Signup and view all the answers

    What is maintained by the analyst after each quality control run?

    <p>A hardcopy of the QC results</p> Signup and view all the answers

    What do control samples analyze alongside?

    <p>Patient specimens</p> Signup and view all the answers

    Which of the following is a key outcome of intralab quality control?

    <p>Immediate identification of analytical errors</p> Signup and view all the answers

    Why are control samples prepared at two levels during internal QC?

    <p>To ensure a wide range of accuracy checks</p> Signup and view all the answers

    What program is used to check QC results after each run?

    <p>Multi-rule quality control program</p> Signup and view all the answers

    Study Notes

    Diagnostic Sensitivity

    • Diagnostic sensitivity measures the test's ability to correctly identify individuals with a disease, yielding valid true-positive results while minimizing false-negative results.
    • High sensitivity is crucial for screening tests to ensure no cases are missed.
    • Sensitivity can be calculated as:
      Sensitivity (%) = (Total number of diseased individuals with positive test result / Total number of diseased individuals tested) × 100

    Diagnostic Specificity

    • Diagnostic specificity indicates the test's ability to correctly identify individuals without the disease, leading to true-negative results and few false-positive outcomes.
    • High specificity is essential for confirmatory tests that validate diagnoses.
    • Specificity can be calculated as:
      Specificity (%) = (Total number of individuals without disease with negative test result / Total number of individuals tested without disease) × 100

    Diagnostic Accuracy

    • Accuracy reflects the method's overall ability to distinguish between diseased and healthy individuals using the proportion of true positives (TP) and true negatives (TN).
    • Accuracy incorporates both TP and TN along with false positives (FP) and false negatives (FN):
      Accuracy = (TP + TN) / (TP + TN + FP + FN)

    Key Terminology

    • True Positive (TP): Correctly identified cases of disease.
    • False Positive (FP): Incorrectly identified cases as having the disease.
    • True Negative (TN): Correctly identified healthy cases.
    • False Negative (FN): Incorrectly identified healthy cases.

    Quality Control Objectives

    • Quality control is intended to ensure:
      • Stability of the testing machine.
      • Quality of reagents used in testing.
      • Minimization of technical (operator) errors.

    Types of Quality Control

    • Intralab Quality Control (Internal QC):

      • Involves analyzing control samples alongside patient specimens.
      • Detects performance changes from standard operations, essential for daily accuracy and precision monitoring.
      • Identifies both random and systematic errors in testing.

    • Internal QC employs blind control samples mixed with patient specimens, typically prepared at two levels representing various patient sample types.

    • Initial control limits are determined by analyzing a pool over 20 consecutive runs, with periodic reevaluation.

    • Results cannot be reported for any analyte declared as "out of control" after internal QC testing.

    • A multi-rule quality control program is used for checking QC results after each test run, with hard copies maintained by the analyst.

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    Description

    Test your understanding of diagnostic sensitivity and specificity. This quiz covers the definitions, importance, and calculations associated with these critical concepts in medical testing. Understand how sensitivity and specificity impact screening tests and disease detection.

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