At least one meta-analysis, systematic review or RCT rated as 1++ and directly applicable to the target population or

A systematic review of RCTs or a body of evidence consisting principally of studies rated as 1+ directly applicable to the target population and demonstrating overall consistency of results

A body of evidence including studies rated as 2++ directly applicable to the target population and demonstrating overall consistency of results or

Extrapolated evidence from studies rated as 1++ or 1+

A body of evidence including studies rated as 2+ directly applicable to the target population and demonstrating overall consistency of results or

Extrapolated evidence from studies rated as 2++

Evidence level 3 or 4 or

Extrapolated evidence from studies rated as 2+

Important practical points for which there is no research evidence nor is there likely to be any research evidence. The Guideline Committee wishes to emphasise these as Good Practice Points.