Table 1

Revised grading system for recommendations in evidence based guidelines

GradeEvidence
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
3Non-analytic studies, for example, case reports, case series
4Expert opinion

  • RCT, randomised controlled trial.