Table 1.

Levels of evidence and grades of the recommendation in EAU Guideline

Level	Type of evidence
1a	Evidence obtained from meta-analysis of randomized trials
1b	Evidence obtained from at least one randomized trial
2a	Evidence obtained from one well-designed controlled study without randomization
2b	Evidence obtained from at least one other type of well-designed quasi-experimental study
3	Evidence obtained from well-designed non-experimental studies, such as comparative studies, correlation studies and case reports
4	Evidence obtained from expert committee reports or opinions or clinical experience of respected authorities

Grade	Nature of recommendation
Strong recommendation (for/against)	The advantages of interventions obviously outweigh the disadvantages or the disadvantages obviously outweigh the advantages
Weak recommendation (for/against)	The advantages and disadvantages of interventions are uncertain or the evidence regardless of its quality shows that the advantages and disadvantages are equal

EAU European Association of Urology