Evidence Based Medicine
ACC/AHA format
Classification of Recommendations
Scottish Intercollegiate Guidelines Network grading recommendations
What it's all about ?:
'Evidence-based Medicine is the enhancement of a clinician's traditional skills in diagnosis, treatment, prevention and related areas through the systemic framing of relevant and answerable questions and the use of mathematical estimates of probability and risk' (A. Donald & T. Greenhalgh 2000)
It relies on the integration of three key elements:
Best research evidence
Clinical expertise
Patient values
How can we go about this ?:
Step one: Ask the question
Which patients?, which treatment or test?, what outcome?
Step two: Find the best evidence
search: electronic, paper, colleagues
Step three: Appraise the evidence you've come across
Is the evidence any good ?
Will it provide a sufficient benefit over your current practise ?
Is it relevant to your patients?
Step four: Combine steps 1-3 with your
clinical expertise and,
considering the patients specific problems
Step five: Evaluate, change if indicated, re-evaluate
As you can see we can help with steps 1-3, the rest still relies on your clinical expertise. This should reassure the EBM sceptics. EBM is not designed to remove the need for clinical expertise but to enhance it.
|
Level |
Description |
|
1++ |
High quality meta analysis, systemic review of RCTs, or RCTs with a very low risk of bias |
|
1+ |
Well conducted meta analysis, systemic review of RCTs, or RCTs with a low risk of bias |
|
1- |
Meta analysis, systemic reviews of RCTs, or RCTs with a high risk of bias |
|
2++ |
High quality systemic reviews of case-control or cohort studies. High quality case-control or cohort studies with a very low risk of confounding, bias, or chance and a high probability that the relationship is casual. |
|
2+ |
Well conducted case control or cohort study with a low risk of confounding, bias, or chance and a moderate probability that the relationship is casual. |
|
2- |
Case control or cohort studies with a high risk of confounding, bias, or chance and a significant risk that the relationship is not casual. |
|
3 |
Non-analytical studies, e.g. case report, case series |
|
4 |
Expert opinion |
It is important to note at this stage that the grade of recommendation reflects the strength of the evidence (methodological quality) and not the clinical importance.
|
Grade |
Description |
|
A |
At least one meta analysis, systemic review, or RCT rated as 1++, and directly applicable to the target population: or A systemic review of RCTs or a body of evidence consisting principally of studies rated as 1+ , directly applicable to the target population, and demonstrating overall consistency of results
|
|
B |
A body of evidence including studies rated as 2++, directly applicable to the target population and demonstrating overall consistency of results; or Extrapolated evidence from studies rated as 1++ or 1+
|
|
C |
A body of evidence including studies rated as 2+, directly applicable to the target population and demonstrating overall consistency of results; or
Extrapolated evidence from studies rated as 2++
|
|
D |
Evidence level 3 or 4; or
Extrapolation of evidence from studies rated as 2+
|
AHA
Classification
of Recommendations
Class
I: Conditions for
which there
is evidence
and/or general agreement
that a
given procedure
or treatment is useful and
Class
II: Conditions for which there is conflicting evidence and/or a
IIa:
Weight of evidence/opinion is
in favor
of usefulness/efficacy.
IIb:
Usefulness/efficacy is
less well
established by evidence/opinion.
Class
III: Conditions for
which there
is evidence
and/or general
Level
of Evidence A: Data are
derived from
multiple randomized clinical trials
or meta-analyses.
Level
of Evidence B: Data are
derived from
a single randomized
trial, or
nonrandomized studies.
Level of Evidence C: Only consensus opinion of experts, case studies, or standard of care.