Epidemiologic note: ODDS ratio (OR)

Nota epidemiológica: razón de ODDS (OR)

Introduction: The odds ratio (OR) is a measure of effect, which has many Spanish equivalents. The term Razón de Odds will be used in this document to designate OR. Throughout history OR has contributed to establish associations in public health. Objective: to conduct an epidemiologic note presenting the main theoretical and practical aspects of odds ratio. Methodology: a search was conducted in the Pubmed, Cochrane Library and LILACS biomedical databases, Google meta-searchers and through the snowball key references strategy. This methodologic note includes an introduction, clinical scenario, concept development, examples, discussion and conclusions. Results: an odds is the quotient between the probability of occurrence of an event (p) over the probability of absence of said event (1-p), OR (odds ratio), is the quotient between two odds. It is a measure of effect which allows researchers to identify how strongly an exposure is associated with an outcome. Conclusions: OR may be determined using different types of study designs and by means of a stratified analysis (Mantel-Haenszel method) and the multivariate method by logistic regression and control for confounding variables.

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