Table 1

Grades of recommendation and evidence levels in support of the recommendations formulated in the Maastricht IV / Florence Consensus Report

Grade of recommendation* Evidence level Type of studies
A11aSystematic review of randomised controlled trial (RCT) of good methodological quality and with homogeneity
1bIndividual RCT with narrow CI
1cIndividual RCT with risk of bias
B22aSystematic review of cohort studies (with homogeneity)
2bIndividual cohort study (including low quality RCT, eg <80% follow-up)
2cNon-controlled cohort studies/ecological studies
33aSystematic review of case–control studies (with homogeneity)
3bIndividual case–control study
C4Case series/poor quality cohort or case–control studies
D5Expert opinion without explicit critical appraisal or based on physiology, bench research or ‘first principles’
  • * The highest grade of recommendation does not always correspond to the highest evidence level.