Screenings in Medicine

Question 1

What are the two website resources Dr. Segars gave us?

Answer 1

1. U.S. Preventive services

2. ePSS

Question 2

What two questions should patients ask their physician when a medical screening test is recommended?

Answer 2

1. How accurate is the screening test you are about to recommend for me?
2. When the test results are announced, how confident will you be in your prediction of whether I do or don’t have the disease.

Question 3

What is a True Positive?

Answer 3

Correctly reports a positive result in a patient that does have the disease. Box A.

Question 4

What is a True Negative?

Answer 4

Correctly reports a negative result in a patient that actually does not have the disease. Box D

Question 5

What is a False Positive?

Answer 5

Incorrectly reports a positive result when the patient does not have the disease. Box B.

Question 6

What is a False Negative?

Answer 6

Incorrectly reports a negative result when the patient actually does have the disease. Box C.

Question 7

What answers the question of how accurate is the screening test you are about to recommend for me?

Answer 7

Sensitivity and Specificity

Question 8

What is Sensitivity?

Answer 8

How well a test can detect the presence of disease when the disease is present. (A/A+C)

Question 9

What is Specificity?

Answer 9

How well a test can detect absence of disease when the disease is absent. (D/B+D)

Question 10

What answers the question of When the test results are announced, how confident will you be in your prediction of whether I do or Don’t have the disease?

Answer 10

1. PPV

2. NPV

Question 11

What is Positive Predictive Value?

Answer 11

How accurately a positive test predicts the presence of disease. (A/A+B)

Question 12

What is Negative Predictive Value?

Answer 12

How accurately a negative test predicts the absence of disease. (D/C+D)

Question 13

As prevalence increased what happens to PPV and NPV?

Answer 13

1. PPV increases

2. NPV Decreases

Question 14

What is Diagnostic Accuracy or Diagnostic precision?

Answer 14

Proportion of total screenings that a patient is correctly identified. (A+D/A+B+C+D)

Question 15

What is a Likelihood Ratio?

Answer 15

Ratio of a given test result for a person with disease/ For a person without disease. Can be calculated for both positive and negative test results. (A/A+C)/(B/B+D) for + inverse for negative.

Question 16

What should the LR+ value be? What should the LR- value be?

Answer 16

1. > 10

2. <0.1

Question 17

What is Validity?

Answer 17

Ability to accurately discern between those that do and those that do not have the disease. Analogous to Precision.

Question 18

What is Internal Validity?

Answer 18

Extent to which results accurately reflect what was being assessed

Question 19

What is External validity?

Answer 19

Extend to which results are applicable to other populations

Question 20

What is Reliability?

Answer 20

Ability of a test to give the same result on repeated uses

Question 21

T/F A valid test is always reliable, yet a reliable test is not always valid

Answer 21

True

Question 22

Why is there crossover in the values of true negatives and true positives?

Answer 22

Variance in people.. these crossover values are what create false positives and negative values