Dugoua et al listed levels of evidence for therapeutic efficacy of an herbal remedy.
|
Evidence of Benefit Based on
|
Strength
|
Grade
|
|
statistically significant evidence of benefit in one or more systematic reviews
|
very strong scientific
|
A
|
|
statistically significant evidence of benefit in one or more properly conducted random control trials (RCT)
|
strong scientific
|
B1
|
|
statistically significant evidence of benefit in one or more random control trials (RCT) with methodologic problems (small size, discrepancies, etc)
|
good scientific
|
B2
|
|
cohort or case control studies
|
weak scientific
|
C
|
|
case reports or case series
|
very weak scientific
|
D
|
|
expert opinion or in vitro experiments
|
indirect
|
E
|
|
based on traditional or historical use, including word of mouth
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historical or traditional
|
F
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where:
• Something that is statistically significant may not be significant in practice.
• Performance of a systematic review presumes multiple properly conducted random control trials.
