2.6 Screenings in Medicine Flashcards Preview

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Flashcards in 2.6 Screenings in Medicine Deck (28)
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1
Q

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

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

What are the 4 screening outcomes?

A

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

3
Q

What does a True positive mean?

A

Test reports positive and the presence of disease does exist.

4
Q

What does a True negative mean?

A

Test reports negative and the presence of disease doesnt exist.

5
Q

What does a False positive mean?

A

Test screams positive but pts doesnt actually have disease.

6
Q

What does a False Negative mean?

A

Test reports no disease but pt does have disease

7
Q

What two terms describe the accuracy of a Test result?

A

Sensitivity and specificity.

8
Q

What does sensitivity mean?

A

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

9
Q

How would you calc sensitivity?

A

True positives / ( All diseased) x 100%

10
Q

What is specificity?

A

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

11
Q

How would you calc specificity?

A

True negatives / (all not diseased) x 100%

12
Q

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

A

Positive Predictive Value and Negative Predictive Value.

13
Q

What does the Positive Predictive Value (PPV) show?

A

How accurately a positive test predicts the presence of disease.

14
Q

How do you calc PPV?

A

True positives / (All positive tests) x 100%

15
Q

What does the Negative Predictive Value (NPV) show?

A

How accurately a negative test predicts the absence of disease.

16
Q

How does one calc NPV?

A

True Negatives / (all Negative Tests) x 100%

17
Q

What is Diagnostic Accuracy (DA)?

A

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

18
Q

How do you calc DA/DP?

A

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

19
Q

What are LRs?

A

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

20
Q

What is a LR+?

A

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

21
Q

How do you calc LR+?

A

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

22
Q

What is LR-?

A

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

23
Q

How would you Calc LR-?

A

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

24
Q

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

A

Bigger than 10

25
Q

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

A

Less than .1

26
Q

What does validity mean?

A

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

27
Q

What does reliability mean?

A

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

28
Q

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

A

True