Epidemiology and Public Health - Early detection and Screening Flashcards
What are the 5 approaches to health promotion ?
What are the three prevention strategies?
Explain all three.
What is the difference between screening and diagnostic tests ?
Why should we screen ?
When can screening be beneficial ?
What are the approaches to screening ? (There is 4)
Give an example for each type of screening stratergy ( all 4).
When is screening not beneficial ?
What are the characteristics of good screening ?
Explain sensitivity vs specificity.
Explain Sensitivity
One measure of test validity issensitivity, i.e., how accurate the screening test is in identifying disease in people who truly have the disease. When thinking about sensitivity, focus on the individuals who, in fact, really were diseased - in this case, the left hand column.
What is the equation for Sensitivity ?
Work out the Sensitivity for this screening test.
132 / (132 + 45) = 0.746
Explain Specificity
Specificity focuses on the accuracy of the screening test in correctly classifying truly non-diseased people.
It is the probability that non-diseased subjects will be classified as normal by the screening test.
The column with non-diseased subjects is emphasized.
Specificity focuses on the probability that the screening test will correctly identify non-diseased subjects.
What is the specificity equation?
What is the specificity in this screening test ?
What is the positive predicted value ?
Positive predictive value (PPV) − The proportion of patients who test positive who actually have the disease
what is a negative predicted value ?
Negative predictive value (NPV) − The proportion of patients who test negative who are actually free of the disease
What is the positive predicted value equation ?
What is the negative predicted value equation ?
Work out the positive predicted value for this equation.
The probability of disease was 132/1,115 = 11.8%.
Work out the negative predicted values of this table.
Explain the yield of a screening program.
What are the adverse effects of screening ?
Work out the specificity for this table.
Work out the
PPV for A and B
Positive Predictive Value (A) = True Positive33/(True Positive33 + False Positive12) = 33/45 = 0.73
Positive Predictive Value (B) = True Positive/( True Positive + False Positive) = 19/35 0.54
What is the sensitivity for this data.
Work out the NPV for A + B.
Negative Predictive Value (A) = True Negative704/(True Neg704 + False Neg5) = 704/709 = 0.9929
Negative Predictive Value (B) = True Negative/(True Neg + False Neg) = 771/774 = 0.9961
What are the positives and negatives that effect uptake of screening programmes
Explain
Sensitivity
Specificity
PPV
NPV
