General Principles of Screening
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Questions and Answers

What is the primary purpose of screening tests?

  • To confirm the diagnosis of a disease
  • To monitor the progression of a known disease
  • To identify unrecognized disease in apparently healthy individuals (correct)
  • To provide treatment options for diagnosed conditions

    • Screening tests require a physician to administer them.

    False

    What is one characteristic of diseases that makes them suitable for screening?

    Chronic diseases with a long natural history.

    Screening can be considered a form of _______ prevention.

    <p>secondary</p> Signup and view all the answers

    Which of the following is NOT a criterion for instituting a screening program?

    <p>The test should be expensive</p> Signup and view all the answers

    Match the following aspects of screening and diagnostic tests:

    <p>Screening tests = Applicable to large groups Diagnostic tests = Evaluation based on a sum of evidence</p> Signup and view all the answers

    A positive finding in a screening test indicates a definitive diagnosis.

    <p>False</p> Signup and view all the answers

    The process of finding people likely to have a disease is called _______.

    <p>screening</p> Signup and view all the answers

    What does sensitivity measure in a screening test?

    <p>The proportion of diseased people correctly identified</p> Signup and view all the answers

    Specificity is the proportion of diseased people who test positive for the disease.

    <p>False</p> Signup and view all the answers

    What is the sensitivity of the screening test if 80 out of 100 diseased individuals test positive?

    <p>80%</p> Signup and view all the answers

    What is the primary purpose of screening tests?

    <p>To detect diseases in asymptomatic individuals</p> Signup and view all the answers

    The positive predictive value of a test indicates what proportion of patients who test positive ________ the disease.

    <p>actually have</p> Signup and view all the answers

    Screening tests are always a basis for treatment.

    <p>False</p> Signup and view all the answers

    Which of the following factors could increase the cost associated with screening tests?

    <p>Labeling or stigma</p> Signup and view all the answers

    Match the following components with their definitions:

    <p>Sensitivity = The proportion of diseased people correctly identified by the test Specificity = The proportion of non-diseased people correctly identified as negative Positive predictive value = The proportion of positive test results that are truly positive Negative predictive value = The proportion of negative test results that are truly negative</p> Signup and view all the answers

    What are the two main types of tests used in case-finding?

    <p>Clinical tests and laboratory tests</p> Signup and view all the answers

    The specificity of the test is calculated as 800 out of 900 non-diseased individuals.

    <p>True</p> Signup and view all the answers

    Screening is used to detect disease predisposition so that individuals can be removed from exposure to specific __________.

    <p>hazards</p> Signup and view all the answers

    If a test has a specificity of 89%, what does this indicate about its performance?

    <p>The test correctly identifies 89% of non-diseased individuals as negative.</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Screening = Test for infection or disease in asymptomatic populations Case-finding = Detect disease in individuals seeking care for other reasons Diagnostic tests = Confirm or refute disease existence in symptomatic patients Validity = Accuracy of a measuring instrument</p> Signup and view all the answers

    Which characteristic of screening tests indicates the ability to deliver consistent results on repeated trials?

    <p>Reliability</p> Signup and view all the answers

    In screening, it is essential for the diseases tested to be rare and not treatable.

    <p>False</p> Signup and view all the answers

    Name a common disease that is appropriate for screening.

    <p>Breast cancer</p> Signup and view all the answers

    What is the formula for calculating Positive Predictive Value (PV+)?

    <p>a / (a + b)</p> Signup and view all the answers

    A high negative predictive value indicates a good cost benefit.

    <p>False</p> Signup and view all the answers

    What is the Negative Predictive Value when 800 out of 820 individuals tested negative?

    <p>98%</p> Signup and view all the answers

    The reliability of a test is affected by biological variation and observer variation, known as _____ variation.

    <p>inter-observer</p> Signup and view all the answers

    Which of the following is NOT a characteristic of a good screening test?

    <p>Complicated procedures</p> Signup and view all the answers

    Match the terms with their meanings:

    <p>Sensitivity = Ability to correctly identify those with the disease Specificity = Ability to correctly identify those without the disease Reliability = Consistency of results across tests Acceptability = The ease with which a test is accepted by the public</p> Signup and view all the answers

    What is one way to increase the reliability of a test?

    <p>Standardization of procedures</p> Signup and view all the answers

    A high prevalence of disease can influence the _____ value of a screening test.

    <p>positive predictive</p> Signup and view all the answers

    Study Notes

    General Principles of Screening

    • Screening involves the presumptive identification of unrecognized diseases through tests applied to apparently healthy individuals.
    • Aims to differentiate between those likely to have a disease and those who do not, but is not intended for diagnosis.
    • Positive findings require further diagnostic evaluation.

    Characteristics of Diseases Suitable for Screening

    • Must be a significant public health issue.
    • Has a known natural history and common prevalence.
    • Effective treatment available if detected early.

    Characteristics of Screening Tests

    • Validity: Ability of tests to accurately measure the presence or absence of a disease, influencing treatment decisions.
    • Reliability: Consistency of the test results when repeated under the same conditions.
    • Acceptability: Tests should be simple, safe, and minimally invasive with no unpleasant implications.

    Sensitivity and Specificity

    • Sensitivity: Proportion of diseased individuals correctly identified by the screening test (e.g., 80% signifies good identification of those with the disease).
    • Specificity: Proportion of non-diseased individuals correctly identified as negative by the test (e.g., 89% signifies good identification of those without the disease).

    Predictive Value of Tests

    • Positive Predictive Value (PV+): Measures the proportion of patients testing positive who actually have the disease; influenced by disease prevalence and test specificity.
    • Negative Predictive Value (PV-): Measures the proportion of patients testing negative who do not have the disease.

    Types of Screening

    • Simple vs. Complex: Simple tests (e.g., rectal exams for prostate cancer) versus more comprehensive tests.
    • Individual vs. Mass Screening: Targeted tests for individuals seeking care versus initiatives in broader populations (e.g., health camps).
    • Routine vs. Ad-hoc: Regular screening programs vs. episodic based on specific exposures.

    Appropriate Situations for Screening

    • Social factors: Importance to individuals and communities, availability of follow-up care, favorable cost-benefit ratios, and high public acceptance.

    Reliability of Screening Tests

    • Ensuring reliability involves standardizing procedures, providing intensive training, conducting periodic checks, and using multiple independent observers.

    The Iceberg Phenomenon

    • Represents the concept that many cases of illness are hidden beneath the surface of what is diagnosed and managed by physicians, emphasizing the importance of proactive screening.

    Screening vs. Diagnostic Tests

    • Distinction lies in application scope; screening tests are conducted on broad populations while diagnostic tests are used on individuals with indications of disease.
    • Screening tests are less expensive and generally less accurate, serving as preliminary evaluations, whereas diagnostic tests provide comprehensive assessments based on multiple symptoms and signs.

    Aims of Screening Programs

    • Detect predisposition to diseases to minimize exposure to risks.
    • Facilitate early-stage detection of diseases for timely treatment intervention.

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    Related Documents

    Screening - A Medical Overview PDF

    Description

    Explore the fundamental concepts of screening in healthcare, including the characteristics of diseases that are suitable for screening and the essential criteria for establishing screening programs. Delve into the iceberg phenomenon and understand what is visible and what lies beneath in patient health.

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