Table 1

Quality of evidence summarised for each of the statements will be graded according to the classification below

Level of evidence
IEvidence obtained from at least one randomised controlled trial (RCT)
II-1Evidence obtained from well-designed controlled trials without randomisation
II-2Evidence obtained from well-designed cohort or case-control study
II-3Evidence obtained from comparison between time or places with or without intervention
IIIOpinion of respected authorities, based on clinical experience and expert committees