EBM for Dummies

Question 1

Statistically significant RCT

Meta-analysis or systematic review of RCT

Answer 1

Level 1

Question 2

Lesser quality RCT
Meta-analysis or systematic review of RCT
Prospective cohort

Answer 2

Level 2

Question 3

Retrospective cohort
Case-control study
Cross-sectional
Meta-analysis or systematic review

Answer 3

Level 3

Question 4

Case study, case series

Answer 4

Level 4

Question 5

Expert opinion
Animal studies
Cadaveric studies

Answer 5

Level 5

Question 6

Ideal study for a PROSPECTIVE study?

Answer 6

RCT

Question 7

Ideal study for RETROSPECTIVE study

Answer 7

Case-control

Question 8

5 problems with EBM

Answer 8

No time
Difficult to interpret
Not useful
Defined differently
Statisticians have concerns

Question 9

Determines how many patients to treat with selective modality until ONE patient shows benefit

Answer 9

NNT

Question 10

Reciprocal of %success in tx group minus the %success in control group

Answer 10

NNT = 1 / (EER-CER)

Question 11

What NNT value determines if a treatment is good?

Answer 11

NNT less than 4

Question 12

Determines how many patients are needed to treat before harmful effects are seen

Answer 12

NNH

Question 13

Reciprocal of the risk of bad outcome in tx group minus risk of bad outcome in control group

Answer 13

NNH = 1/ (EER-CER)

Question 14

Negative NNH means?

Answer 14

The control condition is more likely to harm than the treatment condition

Question 15

Higher the NNH the better or worse?

Answer 15

BETTER

Question 16

Statistic of choice for case-controlled study that shows the odds of having the adverse outcome in the treatment group relative to having the adverse outcome in the control group

Answer 16

Odds Ratio

Question 17

Odds ratios greater than, equal to, and less than 1 indicate?

Answer 17

>1 = bad is caused (NNH)
=1 = neither
<1 = bad is prevented (NNT)

Question 18

Know how to use a 2x2 box for EBM

Answer 18

Divide the top 2 numbers, then divide the bottom two numbers. Finally, divide the 2 numbers you have and that is the odds ratio

Question 19

What is PEER?

Answer 19

The rate of adverse events we would expect in a patient who received no tx or received conventional tx

Question 20

How to calculate PEER

Answer 20

(# of control with adverse) / (# of control with and without adverse)

Question 21

Utilizing PEER and the OR will do what?

Answer 21

Tell you NNT or NNH