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Questions and Answers
Which of the following is NOT a measure of mortality discussed?
Which of the following is NOT a measure of mortality discussed?
Screening tests are used to diagnose diseases in symptomatic individuals.
Screening tests are used to diagnose diseases in symptomatic individuals.
False
What is the Iceberg phenomenon of disease?
What is the Iceberg phenomenon of disease?
It refers to the hidden mass of diseases in a population that are not visible, including pre-symptomatic and subclinical diseases.
The _____ phenomenon highlights that many diseases are hidden beneath the surface and go undiagnosed.
The _____ phenomenon highlights that many diseases are hidden beneath the surface and go undiagnosed.
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Match the following terms with their correct definitions:
Match the following terms with their correct definitions:
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What has been a main evolution in healthcare screenings?
What has been a main evolution in healthcare screenings?
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Annual health examinations were initially designed to detect hidden diseases.
Annual health examinations were initially designed to detect hidden diseases.
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What is the primary purpose of a diagnostic test?
What is the primary purpose of a diagnostic test?
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Lead time in screening refers to the period when treatment begins after symptoms appear.
Lead time in screening refers to the period when treatment begins after symptoms appear.
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Give one example of a condition screened during prescriptive screening.
Give one example of a condition screened during prescriptive screening.
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Screening for __________ helps to control the spread of infectious diseases like tuberculosis.
Screening for __________ helps to control the spread of infectious diseases like tuberculosis.
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Match the following screening types with their descriptions:
Match the following screening types with their descriptions:
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Which of the following is NOT a use of screening?
Which of the following is NOT a use of screening?
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Screening can lead to an earlier diagnosis, thereby improving treatment outcomes.
Screening can lead to an earlier diagnosis, thereby improving treatment outcomes.
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Name one of the two key considerations for criteria of screening.
Name one of the two key considerations for criteria of screening.
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The concept of __________ helps to improve the survival rate after diagnosis.
The concept of __________ helps to improve the survival rate after diagnosis.
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Which of the following is NOT a criterion for screening tests?
Which of the following is NOT a criterion for screening tests?
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A valid screening test has the ability to distinguish between healthy and diseased individuals.
A valid screening test has the ability to distinguish between healthy and diseased individuals.
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What is the term used to describe the accuracy of a screening test?
What is the term used to describe the accuracy of a screening test?
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The test for diabetes that is more valid than glycosuria is called the __________.
The test for diabetes that is more valid than glycosuria is called the __________.
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Match the following terms related to screening tests with their definitions:
Match the following terms related to screening tests with their definitions:
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In a population of 1000 people, how many individuals are considered True-Negative if there are 720 in Group D?
In a population of 1000 people, how many individuals are considered True-Negative if there are 720 in Group D?
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The glucose tolerance test is only useful after the onset of diabetes symptoms.
The glucose tolerance test is only useful after the onset of diabetes symptoms.
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What is the total number of individuals that tested positive for the disease in the screening test example?
What is the total number of individuals that tested positive for the disease in the screening test example?
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A test that provides consistency in results is said to have __________.
A test that provides consistency in results is said to have __________.
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Study Notes
Assessing the Validity and Reliability of Diagnostic and Screening Tests
- Screening tests identify individuals at higher risk of a disease within a population.
- Diagnostic tests confirm or rule out a disease in symptomatic individuals.
- Screening tests help detect diseases early, but diagnostic tests confirm the presence of the disease and guide treatment.
- The "iceberg phenomenon" of disease highlights the hidden proportion of diseases in a community.
Introduction and Review
- Crude Mortality Rate, Cause-Specific Mortality Rate, Case Fatality Rate, Proportionate Mortality, and challenges in mortality measurement were discussed in session 4. These methods are used in public health.
Learning Objectives
- Define validity and reliability of screening and diagnostic tests
- Compare measures of validity: sensitivity and specificity
- Introduce positive and negative predictive value
The Iceberg Phenomenon of Disease
- Diseases in the community are not limited to overt/symptomatic cases.
- Submerged portions include asymptomatic conditions like hypertension, diabetes, anemia, malnutrition, and mental illness.
- These undetected cases are crucial for public health initiatives.
The Concept of Screening
- Screening is the active search for disease in seemingly healthy individuals.
- It aims to find unrecognized disease or defects through rapid tests, examinations, or procedures.
- Screening leads to further tests, treatment, or no further action.
Evolution of Screening Programs in Healthcare
- Annual health examinations evolved to cost-effective screening for hidden diseases in larger populations.
- Methods developed for health examinations to be more accessible, affordable, and efficient for large populations.
- Screening programs initially focused on specific diseases but expanded to become a key element in preventive healthcare.
Screening and Diagnostic Tests (Contrast)
- Screening tests identify individuals who are at a higher risk of having a disease.
- Screening (initial examination) helps identify individuals who might have a disease and are candidates for further testing.
- Diagnostic tests confirm the presence of disease and lead to appropriate treatment.
Diagnostic Tests
- Methods for diagnostic tests include tissue biopsies, blood tests etc.
- These are used for various conditions like gastrointestinal cancer.
Screening Test Overview
- Screening tests (e.g., annual examinations) became cost-effective for larger screenings for early detection of diseases.
Screening and Diagnostic Tests Contrasts (Table 1)
- Screening tests are done on healthy people, while diagnostic tests are done on individuals showing signs or symptoms.
- Screening tests apply to groups; diagnostic tests apply to individuals.
- Screening results can be arbitrary; diagnostic tests use varying criteria.
- Screening often uses a single criterion or cut-off point; diagnostic tests assess multiple issues.
- Screening tests are less accurate and more affordable; diagnostic tests are more accurate but more costly.
- Treatment is not a basis in screening, the initiative comes from investigator/organization; diagnostic tests are used for treatment.
Concept of "Lead Time"
- Early detection (screening) influences survival rates by initiating treatment during asymptomatic phases.
- It extends the time between diagnosis and potential treatment.
Uses of Screening
- Case detection (e.g., neonatal screening) is also a form of prescriptive screening
- Screening protects populations from disease outbreaks.
- It allows for research on disease prevalence and trends.
- Educational opportunities arise from screening programs.
Case Detection "Prescripitive Screening"
- Identifying diseases when symptoms are absent.
- Examples include screening for conditions like bacteriuria during pregnancy, diabetes mellitus, iron deficiency, deafness, diabetes, pulmonary tb or newborn diseases.
Control of Disease "Prospective Screening"
- Screening protects populations from diseases like tuberculosis or syphilis, and can reduce the spread by providing early detection and treatment.
Research Purposes
- Screening provides prevalence and incidence figures.
- Screening programs can be used primarily for research rather than to provide direct treatment.
Educational Opportunities
- Screening programs promote public awareness and educate health professionals.
Criteria for Screening
- Criteria for screening focus on the disease and the test.
Criteria for Screening: 1. Disease
- Important health problem with high prevalence.
- Latent or early asymptomatic stage.
- Available test for early detection.
- Effective treatment available.
Criteria for Screening: 1. Screening Test
- Test acceptability to patients.
- High repeatability (consistency).
- High validity (accuracy) in measuring what is intended to be measured.
Criteria for Screening: Screening Test - Validity (Accuracy)
- The test’s ability to clearly distinguish those with the disease from those who do not.
- Accuracy signifies how closely measured values align with true values.
Glycosuria as a Screening Test
- Glycosuria is a screening test for diabetes though less accurate.
- More accurate test is the glucose tolerance test to detect prediabetes.
- Glucose tolerance tests are used to screen for type 2 diabetes and prediabetes before having symptoms.
- It informs if diabetes is causing existing symptoms.
Measures of Validity of a Test
- Sensitivity and specificity are determined using test results on people with and without a disease.
Example: Screening Test Results by Diagnosis (Table)
- Illustrates various outcomes of screening tests; people with and without the condition.
- Categorizes test results as positive or negative, with respective disease status.
How Good Was the Test? - Sensitivity
- Percentage of people with a disease who test positive.
How Good Was the Test? - Specificity
- Percentage of people without a disease, who test negative.
Evaluation of a Screening Test: Table 3-A
- Table for important metrics of evaluating screening tests
- Sensitivity, Specificity, Positive Predictive Value, and Negative Predictive Value.
Evaluation of a Screening Test: Table 3-B
- More detailed table with specific example data.
Recap and Q&A
- Summary of the coverage on screening of disease measures and their examples
- Definitions
- Sensitivity and Specificity Tests
- Predictive accuracy tests
Preparation for Next Session: Disease Surveillance
- Readings from specific texts for preparing for the next session on disease surveillance.
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Description
Test your knowledge on healthcare screenings and diagnostic tests with this comprehensive quiz. Explore concepts like the Iceberg phenomenon and the evolution of health examinations. Determine the differences between various screening types and their purposes in disease detection.
