Figure 2.

Algorithm for assigning evidence grades to therapy recommendations (step 1). (a) Randomized, controlled trial (RCT) with blinded assessment of outcomes, intention-to-treat analysis, adequate follow-up (ie, at least 90%, or losses to follow-up are too few to materially affect the results) and sufficient sample size to detect a clinically important difference with power greater than 80%. (b) Subgroup analysis was a priori, done within an adequate RCT, one of only a few tested, and there was sufficient sample size within the examined subgroup to detect a clinically important difference with power greater than 80%. (c) Systematic review (SR, also known as meta-analysis) in which the comparison arms were derived from head-to-head comparisons within the same RCT. (d) SR in which the comparison arms were derived from different placebo-controlled RCTs, then extrapolations were made across RCTs