Table 2 Grades of recommendation in the IUA guidelines [13]

A

• Level 1 evidence from randomised controlled trials with consistent results, which are directly applicable to the target population.

B

• Level 1 evidence from a single high-quality randomised controlled trial, which is directly applicable to the target population.

• Level 1 evidence from randomised controlled trials with less consistent results, limited power or other methodological problems, which are directly applicable to the target population.

• Level 1 evidence from randomised controlled trials extrapolated from a different group of patients to the target population.

C

• Level 2 evidence from well-conducted observational studies with consistent results, which are directly applicable to the target population.