Table 1 Recommendation grading
Level of scientific proof provided by the literature (for clinical studies) | Recommendation grading |
|---|---|
Level 1 High-power randomised comparative studies Meta-analysis of randomised comparative studies Decision analysis based on well-conducted studies | A Scientific proof established |
Level 2 Low-power randomised comparative studies Well-conducted non-randomised comparative studies Cohort studies | B Scientific proof presumed |
Level 3 Case–control studies | C Low level of proof |
Level 4 Comparative studies with major bias Retrospective studies Case series Descriptive epidemiological studies (cross-sectional, longitudinal) |