Classes 26-28 Screenings in Medicine Flashcards Preview

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Flashcards in Classes 26-28 Screenings in Medicine Deck (24)
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1
Q

True Positive (TP)

A

Test correctly reports a positive result in a patient that actually does have the disease
(Box A)

2
Q

True Negative (TN)

A

Test correctly reports a negative result in a patient that actually does not have the disease
(Box D)

3
Q

False Positive (FP)

A

Test incorrectly reports a positive result in a patient that actually does not have the disease
(Box B)

4
Q

False Negative (FN)

A

Test incorrectly reports a negative result in a patient that actually does have the disease
(Box C)

5
Q

Sensitivity

A

How well a test can detect presence of disease when in fact disease is present – Positivity-of-test in the diseased
Proportion of time that a TEST is positive in a patient that does have the disease

6
Q

Sensitivity equation

A
Sensitivity = TP/(TP + FN) x 100%
Sensitivity = TP/(all Diseased) x 100%
7
Q

A highly sensitive test has:

A

A low false negative rate

8
Q

Specificity

A

How well a test can detect absence of disease when in fact the disease is absent – Negativity-of-test in the healthy
Proportion of time that a TEST is negative in a patient that does not have the disease

9
Q

Equation for Specificity

A
Specificity = TN/(TN + FP) x 100%
Specificity = TN/(All not diseased) x 100%
10
Q

A highly specific test has:

A

A low false positive rate

11
Q

Positive Predictive Value (PPV)

A

How accurately a positive test predicts the presence of disease
Percentage of TP’s in patients with a positive test (correct prediction)
Also referred to a predictive value-positive (PVP)

12
Q

Equation for PPV

A
PPV = TP/(TP + FP) x 100%
PPV = TP/(All Positive Tests) x 100%
13
Q

Negative Predictive Value (NPV)

A

How accurately a negative test predicts the absence of disease
Percentage of TN’s in patients with a negative test (correct prediction)
Also referred to as Predictive Value-Negative (PVN)

14
Q

Equation for NPV

A
NPV = TN/(TN + FN) x 100%
NPV = TN/(All Negative Tests) x 100%
15
Q

Diagnostic Accuracy (DA) or Diagnostic Precision (DP)

A

Proportion of time that a patient is correctly identified as either having a disease or not having a disease with a positive or negative test, respectively

16
Q

Calculation for DA (or DP)

A

= (TP/TN) / (TP + FP + FN + TN) x 100%

= (TP/TN) / (All patients) x 100%

17
Q

Likelihood Ratio (LR)

A

Probability of a given test result (positive or negative) for a person with the disease / probability of the same test result (+ or -) for a person without the disease

18
Q

Likelihood Ratio Positive (LR+)

A

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

19
Q

Equation for Likelihood Ratio Positive (LR+)

A

[(A/(A+C)) / (B/(B+C))]

Sensitivity/(1-Specificity)

20
Q

Likelihood Ratio Negative (LR-)

A

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

21
Q

Equation for Likelihood Ratio Negative (LR-)

A

[(C/(A+C)) / (D/(B+D))]

(1-Sensitivity) / Specificity

22
Q

LR+ should be _____ to demonstrate the test is most beneficial.

A

> 10

23
Q

LR- should be _____ to demonstrate the test is most beneficial

A
24
Q

ROC (Receiver Operator Curves)

A

A more efficient way to show a relationship between sensitivity & specificity for tests with numerical (continuous) outcomes