Table 1.

Grading statements and recommendations [10]

Recommended grade	Evidence
A	Directly based on category I evidence
B	Directly based on: • Category II evidence, or • Extrapolated recommendation from category I evidence
C	Directly based on: • Category III evidence, or • Extrapolated recommendation from category I or II evidence
D	Directly based on: • Category IV evidence, or • Extrapolated recommendation from category I, II or III evidence
Good practice point	The view of the Guideline Development Group
NICE 2002	Recommendation taken from the NICE technology appraisal
Evidence category	Source
Ia	Systematic review and meta-analysis of randomised controlled trials
Ib	At least one randomised controlled trial
IIa	At least one well-designed controlled study without randomisation
IIb	At least one other type of well-designed quasi-experimental study
III	Well-designed non-experimental descriptive studies, such as comparative studies, correlation studies or case studies
IV	Expert committee reports or opinions and/or clinical experience of respected authorities

Adapted from Eccles M, Mason J (2001) How to develop cost-conscious guidelines. Health Technology Assessment 5 (16)