Understanding observational studies.
The development of evidence-based medicine has encouraged clinicians to consider the best available evidence when making clinical decisions, individualised for the patient.(1,2) A hierarchy of levels of evidence about therapy is described, with the highest being meta-analyses and large, well-designed randomised controlled trials.(3-5) Lower down the hierarchy are observational studies, a group that includes cohort, case-control and cross-sectional studies. Here we describe the benefits and limitations of observational studies, and how to assess their quality.
D019317:Evidence-Based Medicine / Q000379:methods* / Q000592:standards*; D006801:Humans; D064887:Observational Studies as Topic / Q000592:standards*