Table 1.

Evidence grades

A. Randomized, double-blind clinical trial of high quality (for example, sample size calculation, flow chart of patient inclusion, intention-to-treat (ITT) analysis, sufficient sample size)

B. Randomized clinical trial of lesser quality (for example, only single-blind, limited sample size: at least 15 patients per study arm)

C. Comparative trial with severe methodological limitations (for example, not blinded, very small sample size, no randomization) or large retrospective observational study, large open-label-study, registry data

D. Adapted from existing consensus document or statement based on expert opinion voting during consensus conference, evidence non A-C