Categorisation of evidence
| Category | Description of category |
|---|---|
| Evidence from research and other professional literature | |
| A1 | Systematic reviews which include at least one randomised controlled trial |
| A2 | Other systematic and high quality reviews |
| B1 | Individual randomised controlled trials |
| B2 | Non-randomised, experimental studies |
| B3 | Well designed, non-experimental studies, controlled statistically if appropriate; includes well designed qualitative studies |
| C1 | Descriptive and other research (for example, convenience samples) not in B |
| C2 | Case studies and examples of good practice |
| D | Summary articles and discussions of relevant literature (not in A) |
| Evidence from expert opinion | |
| P | Professional opinion based on clinical experience or reports of committees |
| U | User opinion from Older People’s Reference Group or similar |
| C | Carer opinion from Carers’ Focus Group or similar |