title: Causal relationships in medicine.
abstract: The determination of causality is crucial in medicine: for example, a doctor who prescribes a therapeutic regimen believes that it will cure the disease. Causality in medicine is complex, since it can be difficult to establish a cause-effect relationship: arterial hypertension is a known risk factor for stroke, but most people with hypertension will not have a stroke, and most people who have strokes are normotensive. In this article we will define causality, then show how to determine a cause-effect relationship, and finally we will present the type of studies that can provide the strongest evidence on causality.
authors.affiliation: Centro de Estudos de Medicina Baseada na Evidência Faculdade de Medicina de Lisboa, Lisboa, Portugal. avc@fm.ul.pt
authors.forename: António Vaz
authors.initials: AV
authors.lastname: Carneiro
mesh_terms: D015984:Causality; D015331:Cohort Studies; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012189:Retrospective Studies