Table 1.

Grades of recommendations and levels of evidence from the Canadian Task Force on Preventive Health Care

GRADE OR LEVEL	RECOMMENDATION OR EVIDENCE
A	There is good evidence to recommend the clinical preventive action
B	There is fair evidence to recommend the clinical preventive action
C	The existing evidence is conflicting and does not allow a recommendation for or against the use of the clinical preventive action; however, other factors might influence decision making
D	There is fair evidence to recommend against the clinical preventive action
E	There is good evidence to recommend against the clinical preventive action
F	There is insufficient evidence (in quantity or quality) to make a recommendation; however, other factors might influence decision making
I	At least 1 properly conducted randomized controlled trial, systematic review, or meta-analysis
II	Other comparison trials, non-randomized studies, cohort studies, case-control studies, or epidemiologic studies, and preferably more than 1 study
III	Expert opinion or consensus statements

Adapted from the Canadian Task Force on Preventive Health Care.¹