W10_02 evidence based medicine 2 Flashcards Preview

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Flashcards in W10_02 evidence based medicine 2 Deck (17)
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1
Q

note that logic, personal experience, and advice from others are not as good as clinical trials

A

ok

2
Q

recall the case of using the external carotid to bypass the internal carotid, and how that didn’t work

A

stroke rate didn’t change, but acute deaths increased with this experience

3
Q

recall the case of suppressing arrhythmias post-MI

A

anti-arrhythmics killed people because antiarrhythimcs paradoxically cause other arrhythmias!

4
Q

recall the case of the fluoride, which increased the bone mineral density, but resulted in more fractures

A

because fluoride increases cancellous bone, but decreases cortical bone

5
Q

what are the key aspects of RCTs?

A

1: equal chances of being in treatment or control
2: groups treated equally
3: all subjects accounted for at the end of the study
4: intention to treat
5: double-blind
6: all clinically relevant results reported
7: consider both statistical AND clinical significance

6
Q

what’s the difference in efficacy and effectiveness?

A

efficacy: does the Rx work under ideal circumstances?
Effectiveness: does the Rx work in usual circumstances?

7
Q

name 4 kinds of outcomes of clinical trials

A

mortality;
morbidity;
symptomatic status;
surrogate markers

8
Q

what are surrogate outcomes?

A

parameters that are risk factors for an illness

9
Q

note: be careful with surrogates. Just because someone’s cholesterol goes down doesn’t mean they will avoid the infarct

A

ok

10
Q

what’s a meta-analysis

A

quantitative summary of multiple trials for the same therapy, even if their results differ;
convert results into relative risk ratio or odds ratio, then make weighted average

11
Q

what’s type I error (stats)?

A

probability of a real difference even if there isn’t one. P-value. Alpha < 0.05 “proves” this

12
Q

what’s type II error (stats)?

A

probability of no difference when there really is one. Power. Power is 1-beta. Threshold is > 0.8.

13
Q

what’s relative risk reduction?

A

[(risk in untreated)-(risk in treated)] / (risk in untreated)

14
Q

what’s absolute risk reduction?

A

risk in untreated - risk in treated

15
Q

define “number needed to treat”

A

number of people to have to be treated before 1 person benefits.
NNN = 1/ARR

16
Q

define “number needed to harm”

A

NNH = 1/ARI(ncrease)

17
Q

note: good to consider patient values and how they view outcomes to weight the numbers and aide in decision making

A

ok

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