EBHC

Therapies
Dr Bob Phillips
Junior Fellow, Centre for Evidence-based Medicine, Oxford


Therapy
 Ask a question
 Acquire some articles
 Appraise the evidence
 Apply the findings
 Assess your performance
Therapies
 To treat or not to treat?

 Validity
 Importance
 Applicability
Therapies
 Validity
• Was it randomised?
• Was the allocation concealed?
• Were the all the subjects analysed correctly?

• Was it blinded?
• Were the groups similar?
Therapies
 Importance
• What were the results?
• Over what time period?
• With what precision?

Therapies
Number needed to treat
Relative risk reduction
Absolute risk reduction
Event rates
Therapies
Event rates
n with event / total

Control event rate (CER)
Experimental event rate (EER)
Therapies
Absolute risk reduction
difference in two event rates
CER - EER = ARR

Relative risk reduction
proportion of control rate
CER-EER / CER = RRR

Therapies
Number needed to treat
number of extra patients you need to treat to prevent one bad outcome
1 / ARR = NNT
Therapies
95% confidence interval
range within which the true value falls with 95% confidence

use computer (e.g. CATMaker)

Therapies
Application
Can it be applied to my patient?
Can it be done here?
How do patient values affect the decision?
Therapies
Is it valid?
Is it important?
NNT for what
over how long
with what precision
Does it apply?

Therapies
Dr Bob Phillips
Junior Fellow, Centre for Evidence-based Medicine, Oxford