LOE 1: | Randomized Controlled Trials (or meta-analyses of RCTs) |
LOE 2: | Studies using concurrent controls without true randomization (e.g. “pseudo”-randomized) |
LOE 3: | Studies using retrospective controls |
LOE 4: | Studies without a control group (e.g. case series) |
LOE 5: | Studies not directly related to the specific patient/population (e.g. Different patient/population, animal models, mechanical models etc.) |