ICR Week 3

Question 1

List different strategies that physicians use to solve clinical problems

Answer 1

• Hypothetico-deductive
• Algorithm or schema
• Concept Maps: Schema “plus”
• Key finding (key feature or key clue)
• Heuristics (cognitive shortcuts)
• Probabilistic (Bayesian)
• Pattern recognition

Question 2

Describe the key finding clinical strategy:

Answer 2

• Key finding (key feature or key clue)

– Limited differential (splinter hemorrhage)

Question 3

Describe heuristics clinical strategy:

Answer 3

• Heuristics (cognitive shortcuts)
– Consider CNS infection in all patients who present with fever and mental status changes
– Perform arthrocentesis in all patients presenting with acute monoarticular arthritis

Question 4

Describe probabilistic clinical strategy:

Answer 4

• Probabilistic (Bayesian)
– Applying statistical principals to patient encounters
– Experts usually do this without “number crunching”
• Common vs. rare

Question 5

Describe pattern recognition clinical strategy:

Answer 5

• Pattern recognition

– Diagnosis “at a glance”

Question 6

Describe how to construct a problem list:

Answer 6

Problem lists can often be “split” or “lumped”
– “Splitters”–list each problem separately (not grouped)
• Generate unique differential for every problem on list
• Multisystem disease, several new diagnoses

– “Lumpers”–group problems into unifying diagnosis
• Common presentations of familiar diseases

Question 7

Define sensitivity

Answer 7

Sensitivity: SnOUT if test is negative it can be ruled out if the test has a high sensitivity
(True postive rate) Proportion of all people with disease who test positive, or the probability that a test detects disease when disease is present.Value approaching 100% is desirable for ruling
out disease and indicates a low false-negative rate. High sensitivity test used for screening in diseases with low prevalence.

Question 8

Define specificity

Answer 8

Specificity: Sp IN if the test is positive it can be ruled in if the test has a high specificity
(True negative rate) Proportion of all people without disease who test negative, or the probability that a test indicates non-disease when disease is absent. Value approaching 100% is desirable for ruling in disease and indicates a low falsepositive rate. High specificity test used for confirmation after a positive screening test.

Question 9

Calculate positive predictive values

Answer 9

Positive predictive value (PPV)
Proportion of positive test results that are true positive. Probability that person actually has the disease given a positive test result.
= TP / (TP + FP)
PPV varies directly with prevalence or pretest probability: high pretest probability Ž high PPV

Question 10

Calculate negative predictive values

Answer 10

Negative predictive value (NPV):
Proportion of negative test results that are true negative.
Probability that person actually is disease free given a negative test result.
= TN / (FN + TN)
NPV varies inversely with prevalence or pretest probability: high pretest probability Ž low NPV

Question 11

Describe the hypothetico-deductive clinical strategy:

Answer 11

Hypothetico-deductive
– Arrive at the diagnosis by considering each potential Dx in
isolation without comparing/contrasting with other potential Dx
• Inefficient, redundant, but can be accurate
• Used by novice learners

Question 12

Describe the algorithm or schema clinical strategy:

Answer 12

Algorithm or schema
– Arrive at diagnosis through a series of prioritized decision points
or steps
– Work through a series of “yes”/“no” ?s with branch points

Question 13

Describe the concept maps clinical strategy:

Answer 13

Concept Maps: Schema “plus”
– You create + tie concepts together–linking words (or
meaningful connections)
• Causes, manifested by, resulting in, is treated by, such as
– Studies have shown helps organize thoughts,
understanding