Table 1 SIGN grading system 1999–2012
From: The complete European guidelines on phenylketonuria: diagnosis and treatment
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, or RCTs with a low risk of bias |
1- | Meta-analyses, systematic reviews, or RCTs with a high risk of bias |
2++ | High quality systematic reviews of case control or cohort or studies High quality case control or cohort studies with a very low risk of confounding or bias and a high probability that the relationship is causal |
2+ | Well-conducted case control or cohort studies with a low risk of confounding or bias and a moderate probability that the relationship is causal |
2- | Case control or cohort studies with a high risk of confounding or bias and a significant risk that the relationship is not causal |
3 | Non-analytic studies, e.g. case reports, case series |
4 | Expert opinion |
Grades of recommendations | |
| At least one meta-analysis, systematic review, or RCT rated as 1++, and directly applicable to the target population; or A body of evidence consisting principally of studies rated as 1+, directly applicable to the target population, and demonstrating overall consistency of results |
| A body of evidence including studies rated as 2++, directly applicable to the target population, and demonstrating overall consistency of results; or Extrapolated evidence from studies rated as 1++ or 1+ |
| A body of evidence including studies rated as 2+, directly applicable to the target population and demonstrating overall consistency of results; or Extrapolated evidence from studies rated as 2++ |
| Evidence level 3 or 4; or Extrapolated evidence from studies rated as 2+ |
Good practice points | |
| Recommended best practice based on the clinical experience of the guideline development group |
