Evidence Based Medicine

The National Library of Medicine's hierarchical thesaurus, which gives structure and power to the bibliographic data in PubMed and OvidMedline, can be deployed to retrieve articles with evidence. AND the following MeSH with your search results to retrieve studies with evidence, especially for prognosis and etiology/harm questions. PubMed and OvidMedline do not have publication-type limits for these studies.

Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.  Its explosion includes Retrospective Studies.

Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics. Its explosion includes:

• Follow-Up Studies
• Longitudinal Studies
• Prospective Studies
• Retrospective Studies

Studies which observe a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group. 

Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons. 

This overarching MeSH covers studies designed to examine associations, commonly, hypothesized causal relations. They are usually concerned with identifying or measuring the effects of risk factors or exposures.  Its explodable tree includes all the study types on this page plus such MeSH as:

• Cross-sectional Studies
• Randomized Controlled Trials as Topic (an explodable MeSH that retrieves much less than the publication type)