Skip to main content

Table 1 Class of recommendation and level of evidence

From: Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the use of cardiovascular magnetic resonance in pediatric congenital and acquired heart disease

Class (strength) of recommendation (COR)

Level of evidence (LOE)

Class I (strong) Benefit >  >  > Risk

The procedure should be performed

Suggested phrases for recommendations:

• Is recommended

• Is indicated/useful/effective/beneficial

• Should be performed

Level A

• High quality evidence from multiple randomized clinical trials or meta-analyses

• One or more randomized clinical trials corroborated by high quality registry studies

Class IIa (moderate) Benefit >  > Risk

It is reasonable to perform the procedure. Additional studies with focused objectives needed

Suggested phrases for recommendations:

• Is resonable

• Can be useful/effective/beneficial

• Is probably recommended or indicated

Level B

• Moderate quality evidence from multiple randomized clinical trials or meta-analyses

• Moderate quality evidence from 1 or more well-designed, well-executed nonrandomized studies, observational studied or registry studies or meta-analysis of such studies

Class IIb (weak) Benefit > Risk

The procedure may be considered. Additional studies with broad objectives needed. Additional registry data would be helpful

Suggested phrases for recommendations:

• May/might be considered

• May/might be reasonable

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

Level C

• Randomized or nonrandomized observational or registry studies with limitations of design or execution or meta-analysis of such studies

• Physiologic or mechanistic studies in humans

• Consensus of expert opinion based on clinical experience

Class III No Benefit

The procedure is not helpful and of no proven benefit

Suggested phrases for recommendations:

• Is not recommended

• Is not indicated

• Should not be performed/administered

• Is not useful/beneficial/effective

Notes

COR and LOE are determined independently (any COR may be paired with any LOE)

Class III Harm

The procedure incurs excess cost without benefit or is harmful to patients

Suggested phrases for recommendations:

• Is potentially harmful

• Causes harm

• Associated with excess morbidity/mortality

• Should not be performed/administered

A recommendation with LOE B or C does not imply the recommendation is weak. May important clinical questions addressed in guidelines do not lend themselves to clinical trials. Although randomized clinical trials are unavailable, there may be very clear clinical consensus that a particular test is useful or effective

  1. COR, class of recommendation; LOE level of evidence