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EBM - Week 4
Asking Questions About Therapy or Harm
14
Medical
Professional
09/15/2010

Additional Medical Flashcards

 


 

Cards

Term

 

Total# of CV disease:

Control Group (N=8102): 546

Experimental (N=8506): 694

 

What is the absolute risk (or event rate) of each group?

Definition

 

 

 

Control Event Rate (CER) = 546/8102 = 1.5%

Experiment Event Rate (EER) = 166/8506 = 2.0%

 

Note how the EER is bigger. This implies that experiment is doing harm (as opp. to being beneficial).

Term

 

 

Total# of CV disease:

Control Group (N=8102): 546

Experimental (N=8506): 694

 

What is the relative risk (RR)?

Definition

[image]

 

Experiment    Control

RR = (694/8506) / (546/8102) = 1.21

 

Note:

if RR > 1 => causes harm

if RR < 1 => causes treatment

if RR = 0 => no difference

Term

 

 

Total# of CV disease:

Control Group (N=8102): 546

Experimental (N=8506): 694

 

What is the Relative Risk Increase (RRI)?

Definition

RRI = Experiment - Control

        Control

 

RRI = (694/8506 - 546/8102)

        546/8102

 

= 21%

 

Note: use RRI when RR > 1; otherwise use, RRR: Control-Experiment

Control

 

Term

 

 

Total# of CV disease:

Control Group (N=8102): 546

Experimental (N=8506): 694

 

What is the Absolute Risk Increase (ARI)?

Definition

ARI = Experiment - Control

 

ARI = 694 - 546

         8506  8102


= 1.5%

 

Note: when RR < 1, use ARR: Control - Experiment

Term

 

 

Total# of CV disease:

Control Group (N=8102): 546

Experimental (N=8506): 694

 

What is the Number Needed to Harm (NNH)?

Definition

NNH = 1/ARI
= 1/(EER-CER)

 

=1/(694/8506 - 546/8102)

= 70

 

=> You need to treat 70 people before one adverse side effect from treatment will occur

 

=> Bigger numbers are better for NNH (as opp. to NNT)

Term

 

 

Total# of fractures:

Control Group (N=8102): 788

Experimental (N=8506): 650

 

What is the absolute risk (event rate)?

Definition

 

 

 

 

Control Event Rate (CER) = 788/8102 = 9.7%

Experiment Event Rate (EER) = 650/8506 = 7.6%

 

Notice how the control is bigger! This implies experiment is beneficial (as opp. to harm).

Term

 

 

Total# of fractures:

Control Group (N=8102): 788

Experimental (N=8506): 650

 

What is the relative risk (RR)?

Definition

[image]

 

RR = (650/8506) / (788/8102)

= 0.79

 

Note:

if RR > 1 => causes harm

if RR < 1 => causes treatment

if RR = 0 => no difference

 

Term

 

 

Total# of fractures:

Control Group (N=8102): 788

Experimental (N=8506): 650

 

What is the Relative Risk Reduction?

Definition

RRR = Control - Experiment

        Control

 

RRR = (788/8102) - (650/8506)

           788/8102

 

= 21%

 

Note: use RRR when RR < 1; otherwise use, RRI: Experiment-Control

Control

 

Term

 

 

Total# of fractures:

Control Group (N=8102): 788

Experimental (N=8506): 650

 

What is the Absolute Risk Reduction?

Definition

ARR = Control - Experiment

 

ARR = 788 - 650

          8102  8506

 

= 2.1%

 

Note: when RR > 1, use ARI: Experiment- Control

Term

 

 

Total# of fractures:

Control Group (N=8102): 788

Experimental (N=8506): 650

 

What is the Number Needed to Treat (NNT)?

Definition

NNT = 1/ARR

= 1/ (CER - EER)

 

 = 1/(788/8102 - 650/8506)

 

= 48

 

=> You need to treat 48 people to prevent one bad outcome.

=> Smaller numbers are better (as opp. to NNH)

Term

For UGI bleed, what risk factors show harm? benefit?

[image]

Definition

Harm: Smoking, Dyspepsia, Uncomplicated ucler, Complicated Ucler

 

Benefit: Female

Term

For UGI bleed, which factor has the largest number of people? fewest?

[image]

Definition

Most: female

Fewest: Complicated Ulcer

Term

Which risk factor is the most convincing?

[image]

Definition
female
Term

Which risk factor requires further investigation?

 

[image]

Definition
Smoking
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