Evidence-based medicine relies on publication of studies that form the basis of the evidence. The studies vary by design including case reports and case series that propose clinical associations, cross-sectional or longitudinal observational studies with larger sample sizes that demonstrate statistical associations, and randomized control trials (RCTs) that compare interventions in matched groups to provide gold standard experimental evidence and meta-analyses, which distill findings of multiple studies. The concept of level of evidence is often applied to generate a hierarchy of study types based on the type of question being asked, with not all study types being applicable to all study questions, both due to the nature of the question (e.g., an RCT is not the best study for a question of prevalence or incidence) and/or feasibility (e.g., RCT may not be practical for study of a rare, slowly progressing disease). The Oxford Center for Evidence-Based Medicine offers excellent resources on this topic (1-3). There has been increasing recognition of the importance of study design and quality of reporting including development of consensus guidelines for reporting of certain study types (e.g., STROBE and CONSORT). Critical reading of the literature has become a focus at all levels of medical education
