Level | Evidence |
---|---|
Ia | Evidence obtained from meta-analysis of RCTs |
Ib | Evidence obtained from at least one RCT |
IIa | Evidence obtained from at least one well designed controlled study without randomisation |
IIb | Evidence obtained from at least one other type of well designed quasi-experimental study |
III | Evidence obtained from well designed non-experimental descriptive studies such as comparative studies, correlation studies and caseācontrolled studies |
IV | Evidence obtained from expert committee reports of opinions and/or clinical experiences of respected authorities |
Grade | Type of recommendation |
A (Ia, Ib) | Requires at least one RCT as part of a body of literature of overall good quality and consistency addressing the specific recommendation |
B (IIa, IIb, III) | Requires availability of well conducted clinical studies but no RCTs on the topic of recommendation |
C (IV) | Requires evidence from expert committee reports or opinions and/or clinical experience of respected authorities. Indicates absence of directly applicable studies of good quality |
RCT, randomised controlled trial.