Guideline 36: Key to evidence statements and grades of recommendations

Antithrombotic Therapy
Key to evidence statements and grades of recommendations

The definitions of the types of evidence and the grading of recommendations used in this guideline originate from the US Agency for Health Care Policy and Research¹ and are set out in the following tables.

Statements of evidence

Ia	Evidence obtained from meta-analysis of randomised controlled trials.

Ib	Evidence obtained from at least one randomised controlled trial.

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 case studies.

IV	Evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities.

Grades of Recommendations

Requires at least one randomised controlled trial as part of a body of literature of overall good quality and consistency addressing the specific recommendation. (Evidence levels Ia, Ib)

Requires the availability of well conducted clinical studies but no randomised clinical trials on the topic of recommendation. (Evidence levels IIa, IIb, III)

Requires evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities. Indicates an absence of directly applicable clinical studies of good quality. (Evidence level IV)

Good Practice Points

Recommended best practice based on the clinical experience of the guideline development group

[Sign Methodology]

Antithrombotic Therapy Key to evidence statements and grades of recommendations

Antithrombotic Therapy
Key to evidence statements and grades of recommendations