Diagnostic Tests Flashcards Preview

RUSVM Epidemiology 2016 > Diagnostic Tests > Flashcards

Flashcards in Diagnostic Tests Deck (24):
1

Diagnosis

Classify animals as having a disease or not

2

What are the uses of diagnostic tests

Clinical medicine: used for treatment and prognosis
Surveillance: identify changes in disease status in a population
International trade: keep infected animals out
Research: identify and monitor research subjects

3

Dichotomous

only two possible aniswers

4

Continuous

a continuum of possible answers
E.g. Serum chemistry, antibody titers, CBC

5

Hematology diagnostic tests

Measures amount of different cell types in a venous blood sample

6

Biochemical diagnostic tests

Measures enzymes, metabolites, proteins - usually in venous sample

7

Immunological diagnostic tests

use antigen to measure antibodies

8

Pathogen detection tests

detect the pathogen itself or specific parts of it

9

True Positive

Diseased animal that tests positive

10

True negative

non-diseased animal that tests negative

11

False negative

diseased animal that tests negative

12

False Positive

Non-diseased animal that tests positive

13

Sensitivity

the proportion of diseased animals that the test correctly classifies as positive

14

Specificity

the proportion of non-diseased animals that the test correctly classifies as negative

15

Sensitive Test

rules disease OUT

16

Specific test

rules disease IN

17

When do you maximize sensitivity?

when you need to detect all disease or infected animals

18

When do you maximize specificity?

when the cost of a false positive is high and you don't care if there are a lot of false negatives

19

Positive Predictive value

The predictive value of a positive result

20

Negative predictive value

the predictive value of a negative test result

21

Sensitivity Calculation

Number of test positive/Number diseased

22

Specificity calculation

Number of test negative /number non-diseased

23

PPV calculation

Number of diseased/Number test positive

24

NPV Calculation

number of non-diseased/number test negative