Hepatitis C

Evidence levels and recommendation gradings

Key to levels of evidence

High quality meta-analyses, systematic reviews of randomised controlled trials (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 of RCTs, or RCTs with a high risk of bias. 1-

High quality systematic reviews of case control or cohort 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 casual. 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. 2-

Non-analytic studies, eg case reports, case series. 3

Expert opinion. 4

Key to recommendation gradings

Note: The grade of recommendation relates to the strength of the evidence on which the recommendation is based. It does not reflect the clinical importance of the recommendation.

Grade A

At least one meta-analysis, systematic review of RCTs, 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.

Grade A
At least one meta-analysis, systematic review of RCTs, 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
See all recommendation gradingsGrade A

Grade B

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+.

Grade B
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+
See all recommendation gradingsGrade B

Grade C

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++.

Grade C
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++
See all recommendation gradingsGrade C

Grade D

Evidence level 3 or 4; or
Extrapolated evidence from studies rated as 2+.

Grade D
Evidence level 3 or 4; or
Extrapolated evidence from studies rated as 2+
See all recommendation gradingsGrade D

Good practice points

• The sign guidelines
  • About the guideline
    • Background to HCV
    • Development of the guideline
    • Definitions
    • Abbreviations
    • Evidence levels and recommendation gradings
    • References
    • Implementation, resource implications and audit
  • Testing & Diagnosis
  • Referral
  • Management
  • Treatment
• Research & resources
• Action Plan
• Patients and carers
• Useful contacts
• Information leaflets