Table 1 Revised grading system for recommendations in evidence-based guidelines [[10]]
| Â | Levels of evidence |
|---|---|
1++ | High-quality meta-analyses, systematic reviews of RCTs, or RCTs with a very low risk of bias |
1+ | Well-conducted meta-analyses, systematic reviews of RCTs, or RCTs with a low risk of bias |
1− | Meta-analyses, systematic reviews or RCTs, or RCTs with a high risk of bias |
2++ | High-quality systematic reviews of case-control or cohort studies or high-quality case-control or cohort studies with a very low risk of confounding, bias, or chance and a high probability that the relationship is causal |
2+ | Well-conducted case-control or cohort studies with a low risk of confounding, bias, or chance and a moderate probability that the relationship is causal |
2− | Case-control or cohort studies with a high risk of confounding, bias, or chance and a significant risk that the relationship is not causal |
3 | Non-analytic studies, e.g., case reports, case series |
4 | Expert opinion |