Size of Treatment Effect
CLASS IIb
Benefit ≥ Risk
Additional studies with broad
objectives needed; additional registry
data would be helpful
Procedure/Treatment
MAY BE CONSIDERED
CLASS III No Benefit
or CLASS III Harm
▪Recommendation's usefulness/
efficacy less well established
▪Greater conflicting evidence from
multiple randomized trials or meta-
analyses
▪Recommendation that procedure or
treatment is not useful/effective and may be
harmful
▪Sufficient evidence from multiple
randomized trials of meta-analyses
▪Recommendation's usefulness/
efficacy less well established
▪Greater conflicting evidence
from single randomized trial or
nonrandomized studies
▪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
▪Only diverging expert opinion, case
studies, or standard of care
▪Recommendation that procedure or
treatment is not useful/effective and may be
harmful
▪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
a
Data available from clinical trials or registries about the usefulness/efficacy in different
subpopulations, such as sex, age, history of diabetes mellitus, history of prior MI, history of HF, and
prior aspirin use.
b
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.
Procedure/
Test Treatment
COR III:
No benefit
Not Helpful No Proven
Benefit
COR III:
Harm
Excess Cost
w/o Benefit
or Harmful
Harmful to
Patients
