The Level of Evidence for a Randomized Controlled Study

The level of evidence provides guidance to the study quality. Level 2 therapeutic studies consist of well-designed prospective cohort studies, poor quality randomized controlled trials with a follow-up of less than 80% and systematic review of Level 2 studies or non-homogeneous Level 1 studies. When determining the level of evidence, readers must critically appraise the study question, treatment, intervention, and outcomes of the study.