Appendix 1: Definitions of levels of evidence and classes of recommendation used
Level of evidence	Definition
I	Evidence from at least 1 randomized controlled trial
II-1	Evidence from well-designed cohort or caseBcontrol studies, usually from more than 1 centre or research group
II-2	Evidence from well-designed controlled trials but without randomization
II-3	Dramatic results from uncontrolled experiments
III	Opinions of experts, findings from descriptive studies, or reports of expert committees
Class of recommendation	Definition
A	Good evidence to support procedure or treatment
B	Fair evidence to support procedure or treatment
C	Poor evidence to support procedure or treatment
D	Fair evidence that procedure or treatment should not be used
E	Good evidence that procedure or treatment should not be used.

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