Estimate of Certainty (Precision) of Treatment Effect

• Level of evidence of B or C does not imply that recommendation is weak.

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 orNONRANDOMIZED studies

LEVEL C Very limited populations evaluated Only consensus opinion of experts, case studies, or standard or care

• Multiple populations refer to subpopulations such as sex, age, history of diabetes, history of prior myocardial infarction, history of heart failure, and prior aspirin use. Data were available from clinical trials or registries about their usefulness and efficacy.

• Level A: Patients should be broad and clinically useful.

Classification of Recommendations

• Difference between class I and IIa & IIb is benefit vs risk profile

• Level 3 shows a greater risk: No benefit or Harm

• Notice the words used for each when you are reading the guideline

CLASS IBenefit >>> RiskProcedure/TreatmentSHOULD be performed/administered

CLASS IIaBenefit >> RiskAdditional studies with focused objectives neededIt is REASONABLE to perform procedure/administer treatment

CLASS IIbBenefit ≥ Risk Additional studies

with broad objectives needed; additional registry data would be helpful

 Procedure/TreatmentMAY BE CONSIDERED

CLASS III No Benefit

Or CLASS III HarmCLASS IBenefit >>> RiskProcedure/TreatmentSHOULD be performed/administered

CLASS IIaBenefit >> RiskAdditional studies with focused objectives neededIt is REASONABLE to perform procedure/administer treatment

CLASS IIbBenefit ≥ Risk Additional studies with

broad objectives needed; additional registry data would be helpful

 Procedure/TreatmentMAY BE CONSIDERED

CLASS III No Benefit

Or CLASS III Harm

A closer look at classification of recommendations and level of evidence

CLASS IBenefit >>>RiskProcedure/TreatmentSHOULD be performed/administered

LEVEL AMultiple populations evaluated

Data derived from MULTIPLE randomized clinical trials or META-ANALYSES

Recommendation that procedure or treatment is useful/effective Evidence from multiple randomized trials or meta-analyses

LEVEL BLimited populations evaluated

Data derived from a SINGLE randomized trial or NONRANDOMIZED studies

Recommendation that procedure or treatment is useful/effective Evidence from single randomized trial or nonrandomized studies

LEVEL CVery limited populations evaluated

Only consensus opinion of experts, case studies, or standard or care

Recommendation that procedure or treatment is useful/effective Only expert opinion, case studies, or standard of care

Recommendation that procedure or treatment is useful/effective

Only expert opinion, case studies, or

standard of care

Recommendation that procedure or treatment is useful/effective

Evidence from single randomized trial

or nonrandomized studies

Recommendation that procedure or treatment is useful/effective

Evidence from multiple randomized trials or meta-analyses

A closer look at classification of recommendations and level of evidence

CLASS IIaBenefit >> RiskAdditional studies with focused objectives needed It is REASONABLE to perform procedure/administer treatment

LEVEL AMultiple populations evaluated

Data derived from MULTIPLE randomized clinical trials or META-ANALYSES

Recommendation in favor of treatment or procedure being useful/effectiveSome conflicting evidence from multiple randomized trials or meta-analyses

LEVEL BLimited populations evaluated

Data derived from a SINGLE randomized trial or NONRANDOMIZED studies

Recommendation in favor of treatment or procedure being useful/effective Some conflicting evidence from a single randomized trial or nonrandomized studies

LEVEL CVery limited populations evaluated

Only consensus opinion of experts, case studies, or standard or care

Recommendation in favor of treatment or procedure being useful/effective Only diverging expert opinion, case studies, or standard of care

Class IIa Suggested Phrases

• Is reasonable• Can be useful/effective/beneficial• Is probably recommended or

indicated

Recommendation in favor of treatment or procedure being useful/effective

Some conflicting evidence from multiple randomized trials or meta-analyses

Recommendation in favor of treatment or procedure being useful/effective

Some conflicting evidence from a single randomized trial or

nonrandomized studies Recommendation in favor of treatment or procedure being

useful/effective Only diverging expert opinion, case studies, or standard of care

CLASS IIbBenefit ≥ risk Additional studies with broad objectives

needed; additional registry data would be helpful.

Procedure/TreatmentMAY BE CONSIDERED

LEVEL AMultiple populations evaluated

Data derived from MULTIPLE randomized clinical trials or META-ANALYSES

Recommendation’s usefulness/efficacy less well establishedGreater conflicting evidence from multiple randomized trials or meta-analyses

LEVEL BLimited populations evaluated

Data derived from a SINGLE randomized trial or NONRANDOMIZED studies

Recommendation’s usefulness/efficacy less well established Greater conflicting evidence from a single randomized trial or nonrandomized studies

LEVEL CVery limited populations evaluated

Only consensus opinion of experts, case studies, or standard or care

Recommendation’s usefulness/efficacy less well established

Only diverging expert opinion, case studies, or standard of care

A closer look at classification of recommendations and level of evidence

Class IIb Suggested Phrases

• May/might be considered• May/might be reasonable• Usefulness/effectiveness is unknown/unclear/ uncertain or not well established

Recommendation’s usefulness/efficacy less well established

Greater conflicting evidence from multiple randomized trials or meta-analyses

Recommendation’s usefulness/efficacy less well established

Greater conflicting evidence from a single randomized trial

or nonrandomized studies Recommendation’s usefulness/efficacy less well established

Only diverging expert opinion, case studies, or standard of care

A closer look at classification of recommendations and level of evidenceCLASS III No Benefit

Or CLASS III Harm

LEVEL AMultiple populations evaluated

Data derived from MULTIPLE randomized clinical trials or META-ANALYSES

Recommendation that procedure or treatment is not useful/effective and may be harmful Sufficient evidence from multiple randomized trials or meta-analyses

LEVEL BLimited populations evaluated

Data derived from a 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

LEVEL CVery limited populations evaluated

Only consensus opinion of experts, case studies, or standard or care

Recommendation that procedure or treatment is not useful/effective and may be harmful Only expert opinion, case studies, or standard of care

Class III: Harm Suggested Phrases

• Potentially harmful• Causes harm• Associated with excess

morbidity/mortality • Should not be done

Procedure/test

Treatment

COR III:No benefit

Not Helpful No Proven Benefit

CORIII:Harm

Excessive Costw/o Benefit or Harmful

Harmful to Patients

Class III: No Benefit Suggested Phrases

• Is not recommended• Is not indicated• Should not be done• Is not useful/beneficial/effective

Recommendation that procedure or treatment is not useful/effective and may be harmful

Sufficient evidence from multiple randomized trials or meta-analyses Recommendation that procedure or treatment is not useful/effective and may be harmful

Evidence from single randomized trial or nonrandomized

studies Recommendation that procedure or treatment is not useful/effective and may be harmful

Only expert opinion, case studies, or standard of care

All information in the charts from previous slides is taken from this chart.