1 - Intro

Question 1

What are the possible hidden reasons for medical visits? (PAILS)

Answer 1

Psych
Administration
Information
Life Stress
Social isolation

Question 2

What is the time-honored principle for patient care?

Answer 2

Diagnose first and then treatment

Question 3

What circumstances would be appropriate to treat prior to making a diagnosis?

Answer 3

Emergencies or Subacute conditions (like GERD, where improvement in symptoms based on H2 blocker would be diagnostic)

Question 4

What are the 3 principal clinical problem solving methods?

Answer 4

1) Exhaustive
2) Algorithmic (includes Heuristic)
3) Hypothetico-deductive

Question 5

True of False: Diagnostic testing is often more reliable than clinical opinion.

Answer 5

FALSE

Question 6

The number of cases of a particular dz within a defined population at a given point in time.

Answer 6

prevalence

Question 7

The rate of occurrence of new cases of a disease or condition during a given time interval

Answer 7

incidence

Question 8

baseline probability of disease before the results of a diagnostic test is known

Answer 8

pre-test probability

Question 9

Change in disease probability based on a positive or negative test.

So what will you tell your patient about their likelihood of having a disease based on both the pre-test probability and their actual test results?

Answer 9

Post-test probability

Question 10

True or False: Tests with higher sensitivities and specificities will also have high positive and negative predictive values.

Answer 10

True

Question 11

How do you calculate sensitivity?

Answer 11

True positive results divided by the total number of patients who actually have the disease.

TP/(TP + FN)

Question 12

How do you calculate specificity?

Answer 12

True negative results divided by the total number of patients who are actually disease free.

TN/(TN+FP)

Question 13

How do you calculate positive predictive value?

Answer 13

True positive results divided by the total number of patients who tested positive (regardless of actual disease state)

TP/(TP+FP)

Question 14

How do you calculate negative predictive value?

Answer 14

True negative results divided by the total number of patients who tests negative (regardless of actual disease state)

TN/(TN+FN)

Question 15

The sensitivity and specificity of a test are combined into a single entity called ______________

Answer 15

the likelihood ratio (LR)

Question 16

How do you calculate the LR for a TRUE positive? (How likely is it that a positive test result is a true positive rather than a false positive?)

Answer 16

The positive likelihood ratio is the sensitivity divided by one minus the specificity

LR+ = sensitivity/(1 - specificity)

Question 17

Calculate the LR+ for a test whose sensitivity is 0.92 and whose specificity is 0.82.

Is this a good test?

Answer 17

5.1

Good tests will have results&raquo_space;1, so yes, this is a good test.

Question 18

How do you calculate the LR for a FALSE negative?

How likely is it that a negative test result is wrong and the patient actually has the disease?

Answer 18

The negative likelihood ratio is one minus the sensitivity divided by the specificity.

LR- = (1 - sensitivity)/specificity

Question 19

Calculate the LR- for a test whose sensitivity is 0.92 and whose specificity is 0.82.

Is this a good test?

Answer 19

0.098

Good LR- tests will have results «1, so yes, this is a good test.

Question 20

Why are likelihood ratios better than predictive values?

Answer 20

Because the results of predictive values will vary based on the prevalence of disease

Question 21

What are the 3 main reasons for ordering laboratory tests?

Answer 21

1) screening
2) identify or confirm dx
3) monitor dz status

Question 22

If you suspect a disease and you’d like to diagnose it definitively, use a test with high ____________. However, if you’d like to rule out a diagnosis, use a test with high______________.

Answer 22

sensitivity, specificity

Question 23

What 4 major factors influence a clinician’s decision to treat?

Answer 23

1) risk/benefit
2) cost
3) confidence in dx
4) seriousness of disease

Question 24

What is the term for the “threshold” at which a clinician will chose to actively treat a patient?
(Threshold meaning: are you 70% confident, 85% confident, etc…. that your patient has a given disease?)

Answer 24

“benchmark for action”

Question 25

Which treatment decision making model assumes that the physician is best qualified to make decisions for the patient and does not place very much, if any, responsibility on the patient?

Answer 25

Paternalistic Model

Question 26

Which treatment decision making model assumes that the informed patient is best qualified to make decisions for themselves? Here the physician answers all questions and provides ample information but does not express clinical preferences and ultimately leaves decisions to the patient.

Answer 26

Informed Model

Question 27

Which treatment decision making model assumes that decisions are best made by sharing information and preferences between clinician and patient. Risks and benefits are evaluated together and decisions are made together.

Answer 27

Shared Model