Table 2

GRADE system for grading recommendations

Strength of the recommendationQuality of the evidence
1=strongly recommended
2=weakly recommended
A=high quality: RCT(s)
B=moderate quality: downgraded RCT(s) or upgraded observational study(s)
C=low quality: observational study(s)
D=very low quality: downgraded observational study(s)
Factors determining the strength of recommendations:
  • Balance between desirable and undesirable effects

  • Quality of evidence

  • Values and preferences

  • Costs of the intervention

Factors that may decrease QoE:
  • Study limitations

  • Inconsistency of results

  • Indirectness of evidence

  • Imprecision

  • Publication bias

Factors that may increase QoE:
  • Large magnitude of effect

  • Plausible confounding factors would reduce any demonstrated effect

  • Dose–response gradient

  • GRADE, Grading of Recommendations, Assessment, Development and Evaluations; QoE, quality of the evidence; RCT, randomised controlled trial.