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Table 2 Class (Strength) of Recommendation [4]

From: Representation of cardiovascular magnetic resonance in the AHA / ACC guidelines

Class of recommendation

Definition

Suggested phrases for writing recommendations

Class I (strong)

Benefit >> > Risk

• is recommended

• is indicated / useful / effective / beneficial

• should 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

Class IIa (Moderate)

Benefit > > Risk

• Is reasonable

• Can be useful / effective / beneficial

• Comparative-Effectiveness phrases

 − Treatment / strategy A is probably recommended / indicated in preference to treatment B

 − It is reasonable to choose treatment A over treatment B

Class IIb (Weak)

Benefit ≥ Risk

• May / might be reasonable

• May / might be considered

• Usefulness / effectiveness is unknown / unclear / uncertain or not well established

Class III: No benefit (Moderate)

Benefit = Risk

• Is not recommended

• Is not indicated / useful / effective / beneficial

• Should not be performed / administered / other

Class III: Harm (Strong)

Risk > Benefit

• Potentially harmful

• Causes harm

• Associated with excess morbidity / mortality

• Should not be performed / administered / other