Table 2

NHLBI Grading of the Strength of Recommendations

GradeStrength of Recommendation
AStrong recommendation
There is high certainty based on evidence that the net benefit is substantial.
BModerate recommendation
There is moderate certainty based on evidence that the net benefit is moderate to substantial, or there is high certainty that the net benefit is moderate.
CWeak recommendation
There is at least moderate certainty based on evidence that there is a small net benefit.
DRecommendation against
There is at least moderate certainty based on evidence that there is no net benefit or that risks/harms outweigh benefits.
EExpert opinion (“There is insufficient evidence or evidence is unclear or conflicting, but this is what the Work Group recommends.”)
Net benefit is unclear. Balance of benefits and harms cannot be determined because of no evidence, insufficient evidence, unclear evidence, or conflicting evidence, but the Work Group thought it was important to provide clinical guidance and make a recommendation. Further research is recommended in this area.
NNo recommendation for or against (“There is insufficient evidence or evidence is unclear or conflicting.”)
Net benefit is unclear. Balance of benefits and harms cannot be determined because of no evidence, insufficient evidence, unclear evidence, or conflicting evidence, and the Work Group thought no recommendation should be made. Further research is recommended in this area.

ECG indicates electrocardiogram; MI, myocardial infarction; and NHLBI, National Heart, Lung, and Blood Institute.

  • In most cases, the strength of the recommendation should be closely aligned with the quality of the evidence; however, under some circumstances, there may be valid reasons for making recommendations that are not closely aligned with the quality of the evidence (e.g., strong recommendation when the evidence quality is moderate, such as smoking cessation to reduce cardiovascular disease risk or ordering an ECG as part of the initial diagnostic work-up for a patient presenting with possible MI). Those situations should be limited and the rationale explained clearly by the Work Group.

  • Net benefit is defined as benefits minus risks/harms of the service/intervention.