Size of treatment effect | |||||||
---|---|---|---|---|---|---|---|
CLASS I Benefit>>>Risk Procedure/treatment SHOULD be performed/administered | CLASS IIA Benefit>>>Risk Additional studies with focused objectives needed IT IS REASONABLE to perform procedure/administer treatment | 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 | ||||
Procedure/test | Treatment | ||||||
COR III: No benefit | Not helpful | No proven benefit | |||||
COR III Harm | Excess cost without benefit or harmful | Harmful to patients | |||||
Estimate of certainty (precision) of treatment effects | LEVEL A Multiple populations evaluated* Data derived from multiple randomized clinical trials or meta-analyses |
|
|
|
| ||
LEVEL B Limited populations evaluated* Data derived from a single randomized trial or non-randomized studies |
|
|
|
| |||
LEVEL C Very limited populations evaluated* Only consensus opinion of experts, case studies, or standard of care. |
|
|
|
| |||
Suggested phrases for writing recommendations | Should Is recommended Is indicated Is useful/effective/beneficial | Is reasonable Can be useful/effective/beneficial Is probably recommended or indicated | May/might be considered may/might be reasonable Usefulness/effectiveness is unknown/unclear/uncertain or not well established | COR III No benefit 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 | ||
Comparative Effectiveness phrases | Treatment/strategy A is recommended/indicated in preference to treatment B Treatment A should be chosen over treatment B | Treatment/strategy A is probably recommended/indicated in preference to treatment B It is reasonable to choose treatment A over treatment B |
A recommendation with LOE B or C does not imply that the recommendation is weak. Many important clinical questions addressed in the guidelines do not lend themselves to clinical trials. Although randomized trials are unavailable, there may be a very clear clinical consensus that a particular test or therapy is useful or effective.
*Data available from clinical trials or registries about the usefulness/efficacy in different subpopulations, such as sex, age, history of diabetes, history of prior myocardial infarction, history of heart failure, and prior aspirin use.
†For comparative effectiveness recommendations (Class I and IIa; LOE A and B only), studies that support the use of comparator verbs should involve direct comparisons of the treatments or strategies being evaluated.
ACC/AHA, American College of Cardiology/American Heart Association.