2.6 Screenings in Medicine

Question 1

What are 2 questions you should ask your physician when a medical screening test is recommended?

Answer 1

1. How accurate is the test. 2. How confident will you be in your prediction of whether i do or dont have disease

Question 2

What are the 4 screening outcomes?

Answer 2

True positive. True Negative. False Positive. False negative.

Question 3

What does a True positive mean?

Answer 3

Test reports positive and the presence of disease does exist.

Question 4

What does a True negative mean?

Answer 4

Test reports negative and the presence of disease doesnt exist.

Question 5

What does a False positive mean?

Answer 5

Test screams positive but pts doesnt actually have disease.

Question 6

What does a False Negative mean?

Answer 6

Test reports no disease but pt does have disease

Question 7

What two terms describe the accuracy of a Test result?

Answer 7

Sensitivity and specificity.

Question 8

What does sensitivity mean?

Answer 8

How well a test can detect presence of disease when in fact disease is present.

Question 9

How would you calc sensitivity?

Answer 9

True positives / ( All diseased) x 100%

Question 10

What is specificity?

Answer 10

How well a test can detect absence of disease when the disease is absent.

Question 11

How would you calc specificity?

Answer 11

True negatives / (all not diseased) x 100%

Question 12

What two terms describe how confident the doctor will be about predicting if the pt will have disease or not?

Answer 12

Positive Predictive Value and Negative Predictive Value.

Question 13

What does the Positive Predictive Value (PPV) show?

Answer 13

How accurately a positive test predicts the presence of disease.

Question 14

How do you calc PPV?

Answer 14

True positives / (All positive tests) x 100%

Question 15

What does the Negative Predictive Value (NPV) show?

Answer 15

How accurately a negative test predicts the absence of disease.

Question 16

How does one calc NPV?

Answer 16

True Negatives / (all Negative Tests) x 100%

Question 17

What is Diagnostic Accuracy (DA)?

Answer 17

Proportion of total screenings that a pt is correctly identified as either having a disease (True positive) or not having a disease (True negative) with either a positive or negative test

Question 18

How do you calc DA/DP?

Answer 18

(True Positive + True negative) / (All patients) + 100%

Question 19

What are LRs?

Answer 19

Likelihood ratios, division on 2 numbers. Simple ppl with disease in numerator/ppl who dont have disease.

Question 20

What is a LR+?

Answer 20

Probability of a positive test in the presense of disease / probability of a positive test in the absence of disease

Question 21

How do you calc LR+?

Answer 21

Sensitivity / (1-specificity). Which is [A/(A+C)]/ [B/( B+D)]

Question 22

What is LR-?

Answer 22

Probability of a negative test in the presence of disease / probability of a negative test in the absence of disease.

Question 23

How would you Calc LR-?

Answer 23

(1-sensitivity)/Specificity. Which is [C/(A+C) / [D/ (B+D)]

Question 24

What should the test show for LR+ so its significant?

Answer 24

Bigger than 10

Question 25

What should the test show for LR- to so its significant?

Answer 25

Less than .1

Question 26

What does validity mean?

Answer 26

Ability to accurately discern between those that do and dont have disease

Question 27

What does reliability mean?

Answer 27

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

Question 28

True or False? A valid test is always reliable but a reliable test is not always valid.

Answer 28

True