Screenings in Medicine Flashcards
(22 cards)
What are the two website resources Dr. Segars gave us?
- U.S. Preventive services
2. ePSS
What two questions should patients ask their physician when a medical screening test is recommended?
- How accurate is the screening test you are about to recommend for me?
- When the test results are announced, how confident will you be in your prediction of whether I do or don’t have the disease.
What is a True Positive?
Correctly reports a positive result in a patient that does have the disease. Box A.
What is a True Negative?
Correctly reports a negative result in a patient that actually does not have the disease. Box D
What is a False Positive?
Incorrectly reports a positive result when the patient does not have the disease. Box B.
What is a False Negative?
Incorrectly reports a negative result when the patient actually does have the disease. Box C.
What answers the question of how accurate is the screening test you are about to recommend for me?
Sensitivity and Specificity
What is Sensitivity?
How well a test can detect the presence of disease when the disease is present. (A/A+C)
What is Specificity?
How well a test can detect absence of disease when the disease is absent. (D/B+D)
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?
- PPV
2. NPV
What is Positive Predictive Value?
How accurately a positive test predicts the presence of disease. (A/A+B)
What is Negative Predictive Value?
How accurately a negative test predicts the absence of disease. (D/C+D)
As prevalence increased what happens to PPV and NPV?
- PPV increases
2. NPV Decreases
What is Diagnostic Accuracy or Diagnostic precision?
Proportion of total screenings that a patient is correctly identified. (A+D/A+B+C+D)
What is a Likelihood Ratio?
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.
What should the LR+ value be? What should the LR- value be?
- > 10
2. <0.1
What is Validity?
Ability to accurately discern between those that do and those that do not have the disease. Analogous to Precision.
What is Internal Validity?
Extent to which results accurately reflect what was being assessed
What is External validity?
Extend to which results are applicable to other populations
What is Reliability?
Ability of a test to give the same result on repeated uses
T/F A valid test is always reliable, yet a reliable test is not always valid
True
Why is there crossover in the values of true negatives and true positives?
Variance in people.. these crossover values are what create false positives and negative values
