Heart Failure Table 4

Table 4. Size of treatment effect
	Class I Benefit >>> Risk	Class IIa Benefit >> Risk Additional studies with focused objectives needed	Class IIb Benefit ≥ Risk Additional studies with broad objectives needed; additional registry data would be helpful	Class III Benefit ≥ Risk No additional studies needed
	Procedure/treatment should be performed/administered	It is reasonable to perform/administer treatment	Procedure/treatment may be considered	Procedure/treatment should not be performed/administered since it is not helpful and may be harmful
Level A Multiple (3-5) population risk strata evaluated	Recommendation that procedure or treatment is useful/effective Sufficient evidence from multiple randomized trials or non-randomized trials	Recommendation in favor of treatment or procedure being useful/effective Some conflicting evidence from multiple randomized trials or meta-analyses	Recommendation’s usefulness/efficacy less well established Greater conflicting evidence from multiple randomized trials or meta-analyses	Recommendation that procedure or treatment not useful/effective and may be harmful Sufficient evidence from multiple randomized trials or meta-analyses
Level B Limited (2-3) population risk strata evaluated	Recommendation that procedure or treatment is useful/effective Limited evidence from single randomized trial or non-randomized studies	Recommendation in favor of treatment or procedure being useful/effective Some conflicting evidence from single randomized trial or non-randomized studies	Recommendation’s usefulness/efficacy less well established Greater conflicting evidence from single randomized trial or non-randomized studies	Recommendation that procedure or treatment not useful/effective and may be harmful Limited evidence from single randomized trial or non-randomized studies
Level C Very limited (1-2) population risk strata evaluated	Recommendation that procedure or treatment is useful/effective Only experts opinion, case studies, or standard-of-care	Recommendation in favor of treatment or procedure being useful/effective Only diverging expert opinion case studies, or standard-of-care	Recommendation’s usefulness/efficacy less well established Only diverging expert opinion case studies, or standard-of-care	Recommendation that procedure or treatment not useful/effective and may be harmful Only expert opinion case studies, or standard-of-care