W10_01 evidence based medicine Flashcards Preview

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Flashcards in W10_01 evidence based medicine Deck (30)
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1
Q

define evidence based medicine

A

the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients

2
Q

what’s a diagnostic test?

A

have a presenting problem, make a hypothesis, using test to check hypothesis

3
Q

recall the 4 approaches to diagnosis (Ps)

A

possibilistic
probabilistic
prognostic
pragmatic

4
Q

what’s D-dimer?

A

a breakdown product of a crosslinked fibrin mesh - indicates that there was a clot

5
Q

what’s the threshold for d-dimer interpretation?

A

_ 500mg/L means positive for thrombosis

6
Q

what’s type I error?

A

“false positive”. Disease is absent, but test is positive.

7
Q

what’s type II error?

A

“false negative”. Disease is present, but test is negative

8
Q

what’s sensitivity?

A

proportion of those with the disease that test positive

9
Q

what’s specificity?

A

proportion of those without the disease that test negative

10
Q

what’s ruling out?

A

if the test is negative, and the test is very sensitive. Nearly everyone who has the disease tests positive

11
Q

what’s ruling in?

A

if the test is positive, and the test is very specific. Nothing else gives this positive test result

12
Q

how to maximize sensitivity?

A

low cutoff

13
Q

how to maximize specificity?

A

high cutoff

14
Q

what’s the receiver operating characteristic (ROC) curve?

A

specificity vs sensitivity

15
Q

what’s the gold standard for trisomy 21?

A

amniocentesis w karyotyp

16
Q

what’s the gold standard for ectopic pregnancy?

A

laparoscopy

17
Q

what’s the gold standard for coronary artery disease?

A

coronary anteriogram

18
Q

what’s the gold standard for appendicitis?

A

CT abdo

19
Q

what’s the gold standard for alcoholism?

A

detailed interview

20
Q

what’s the gold standard for pulmonary embolism?

A

pulmonary angiogram

21
Q

what’s are predictive values?

A

given the test results, how likely are they to have the disease?

22
Q

define PPV?

A

PPV = TP/(TP+FP)

23
Q

define NPV?

A

NPV = TN/(TN+FN)

24
Q

note: bayes’ theorem allows us to calculate the post-test probability, given the pre-test probability

A

ok

25
Q

when are test/treatment thresholds low?

A

serious disease and/or easy/inexpensive test/treatment to do

26
Q

what’s the likelihood ratio?

A

P(result|disease)/P(result|~disease)

27
Q

note: pretest probability can be converted to post-test probability via the likelihood ratio

A

notice: numerator is sensitivity, denominator is 1-specificity

28
Q

note: post-test odds = pretest odds X likelihood

A

ok

29
Q

what likelihood ratios suggest to rule disease in?

A

LR > 5 to 10

30
Q

what likelihood ratios suggest to rule disease out?

A

LR < 0.1 to 0.2

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