Diagnosis studies

Question 1

What are the answerable questions in EBM?

Answer 1

Patient
Intervention
Comparison
Outcome

Question 2

What are the steps of EBM?

Answer 2

Ask questions
Search for evidence
Critically appraise
Integrate
Evaluate

Question 3

When are diagnostic studies used?

Answer 3

Screen a population
Diagnose a pt
Pt f/u

Question 4

What are the disadvantages of diagnosis studies?

Answer 4

May be expensive
Can risk morbidity/mortality
May cause discomfort

Question 5

Are diagnosis studies randomized?

Answer 5

No

Question 6

What are the four questions to ask when critically appraising diagnosis studies?

Answer 6

1. What are the results
2. Is the study valid
3. Are results important
4. Will results help my pt

Question 7

What should always be included in diagnostic studies?

Answer 7

Comparison to the gold standard

Question 8

What are the indications that a study is of clinical importance?

Answer 8

High sensitivity/specificity

Question 9

The usefulness of any diagnostic test is based on what?

Answer 9

Its accuracy in identifying the disorder

Question 10

What are likelihood ratios?

Answer 10

Predict the likelihood of a certain result in a pt WITH the target disorder, and one WITHOUT

Question 11

True or false: likelihood ratios are essential in analysis of diagnostic studies

Answer 11

False-useful, but not essential

Question 12

What is the equation for sensitivity?

Answer 12

True pos / True pos + false neg

Question 13

What is the equation for specificity?

Answer 13

True neg / False pos + true neg

Question 14

Does a specific test rule in or out?

Answer 14

rules in

Question 15

Does a sensitive test rule in or out?

Answer 15

out

Question 16

What is the incidence?

Answer 16

How many new cases occur in a given period of time

Question 17

What is the prevalence?

Answer 17

How many cases are in a given population, old or new

Question 18

What is the pretest probability?

Answer 18

all pos / all results (prevalence in a population)

Question 19

What is the posttest probability?

Answer 19

Post-test odds/post test odds +1

Question 20

A good test will do what to posttest probability?

Answer 20

Increase it significantly

Question 21

What are odds?

Answer 21

with a condition / # without

Question 22

How do you calculate odds knowing probability?

Answer 22

Probability / probability -1

Question 23

What is a positive likelihood ratio?

Answer 23

sensitivity / 1-specificity

“the probability of a person who has the disease testing positive divided by the probability of a person who does not have the disease testing positive.”

Question 24

What is a negative likelihood ratio?

Answer 24

1-sensitivity / specificity

“the probability of a person who has the disease testing negative divided by the probability of a person who does not have the disease testing negative”

Question 25

What is a likelihood ratio is =1?

Answer 25

Post-test probability = pretest probability

Question 26

A likelihood ratio >1 indicates what?

Answer 26

Increases the probability of finding disease

Question 27

A likelihood ratio

Answer 27

Decreases the probability of finding disease

Question 28

What does Bayes’ theorem mean?

Answer 28

The chance of selecting an individual who has a condition is directly related to the prevalence in the population