Size of Treatment Effect
CLASS IIb
CLASS III No Benefit or
Benefit ≥ Risk
CLASS III Harm
Additional studies with broad
Procedure/
objectives needed; additional registry
Test
data would be helpful
Not Helpful
COR III:
Procedure/Treatment
No benefit
MAY BE CONSIDERED
Excess Cost
COR III:
w/o Benefit
Harm
or Harmful
▪Recommendation's usefulness/
efficacy less well established
▪Greater conflicting evidence from
multiple randomized trials or metaanalyses
▪Recommendation's usefulness/
efficacy less well established
▪Greater conflicting evidence
from single randomized trial or
nonrandomized studies
Treatment
No Proven
Benefit
Harmful to
Patients
▪Recommendation that procedure or
treatment is not useful/effective and may be
harmful
▪Sufficient evidence from multiple
randomized trials of meta-analyses
▪Recommendation that procedure or
treatment is not useful/effective and may be
harmful
▪Evidence from single randomized trial or
nonrandomized studies
▪Recommendation's usefulness/
efficacy less well established
▪Recommendation that procedure or
treatment is not useful/effective and may be
▪Only diverging expert opinion, case harmful
studies, or standard of care
▪Only expert opinion, case studies, or
standard of care
may/might be considered
may/might be reasonable
usefulness/effectiveness is unknown/
unclear/uncertain or not well
established
COR III: No Benefit
is not recommended
is not indicated
should not be
performed/
administered/other
is not useful/
beneficial/effective
COR III: Harm
potentially harmful
causes harm
associated with excess
morbidity/mortality
should not be
performed/
administered/other
b
Data available from clinical trials or registries about the usefulness/efficacy in different
subpopulations, such as sex, age, history of diabetes, history of prior MI, history of HF, and prior
ASA use.
c
For comparative effectiveness recommendations (Class I and IIa; Level of Evidence A and B only),
studies that support the use of comparator verbs should involve direct comparisons of the treatments
or strategies being evaluated.
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