JNC guidelines classification scheme

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rim Halaby, M.D. [2]

Evidence Quality Rating

Quality Rating	Type of Evidence
High	Well-designed, well-executed randomized clinical trials (RCT) that adequately represent populations to which the results are applied and directly assess effects on health outcomes Well-conducted meta-analyses of such studies Highly certain about the estimate of effect; further research is unlikely to change our confidence in the estimate of effect
Moderate	RCTs with minor limitations affecting confidence in, or applicability of, the results Well-designed, well-executed non–randomized controlled studies and well-designed, well-executed observational studies Well-conducted meta-analyses of such studies Moderately certain about the estimate of effect; further research may have an impact on our confidence in the estimate of effect and may change the estimate
Low	RCTs with major limitations Non–randomized controlled studies and observational studies with major limitations affecting confidence in, or applicability of, the results Uncontrolled clinical observations without an appropriate comparison group (eg, case series, case reports) Physiological studies in humans Meta-analyses of such studies Low certainty about the estimate of effect; further research is likely to have an impact on our confidence in the estimate of effect and is likely to change the estimate.

Strength of Recommendation

Grade	Strength of Recommendation	Explanation
A	Strong recommendation	There is high certainty based on evidence that the net benefit is substantial.
B	Moderate 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.
C	Weak recommendation	There is at least moderate certainty based on evidence that there is a small net benefit.
D	Recommendation against	There is at least moderate certainty based on evidence that it has no net benefit or that risks/harms outweigh benefits.
E	Expert opinion	"There is insufficient evidence or evidence is unclear or conflicting, but this is what the committee 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 committee thought it was important to provide clinical guidance and make a recommendation. Further research is recommended in this area.
N	No 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 committee thought no recommendation should be made. Further research is recommended in this area.

• The strength of recommendation grading system used in this guideline was developed by the National Heart, Lung, and Blood Institute’s (NHLBI’s) Evidence-Based Methodology Lead (with input from NHLBI staff, external methodology team, and guideline panels and work groups) for use by all the NHLBI CVD guideline panels and work groups during this project.

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