Table 1.
Evidence level of systematic reviews
| Score | Source of evidence |
|---|---|
| 1++ |
High quality meta analyses or systematic reviews of RCT’s |
| 1+ |
Well conducted meta analyses or systematic reviews of RCT’s |
| 1- |
Meta analyses or systematic reviews of RCT’s |
| 2++ |
High quality systematic reviews of case control or cohort studies |
| 2+ |
Well conducted case control or cohort studies with low risk of bias |
| 2- |
Case control or cohort studies with high risk of bias |
| 3 |
Case reports or case series |
| 4 | Expert opinion or formal consensus |
From Scottish Intercollegiate Guidelines Network [13].