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A dictionary of epidemiology
  1. José Leopoldo Ferreira Antunes
  1. University of São Paulo, School of Dentistry, 2227 Av. Prof. Lineu Prestes, 05508–900 São Paulo, SP, Brazil; leopoldo{at}

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When the first edition of A Dictionary of Epidemiology was launched in 1983,1 its principal aim was to facilitate communication among health professionals. The field was relatively young and comprised complex interdisciplinary relations ranging from the biomedical sciences to statistics and the social sciences. The International Epidemiological Association (IEA) co-sponsored the project with the aim of developing certain standards for teaching, research reports and communication of epidemiological findings to the public. This is a well-known history: John M Last, the emeritus professor of epidemiology and community medicine from the University of Ottawa, Canada, was appointed as the editor of A Dictionary…, and kept ahead of the task during the subsequent decades. The original slim pocket book grew substantially with each re-edit,24 keeping pace with the remarkable developments in the discipline.

When the fourth edition was launched in 2001, John Last told me with a smile that he would die soon, supposedly to increase the value of the signature he had just handwritten in my book. Fortunately, he did not, and his love for dictionary-making allowed him to produce his A Dictionary of Public Health,5 and to collaborate in the recently launched fifth edition of A Dictionary…,6 now edited by Miquel Porta, professor of preventive medicine and public health from the Universitat Autònoma de Barcelona, senior scientist of the Institut Municipal d’Investigació Mèdica in Barcelona, Spain, and collaborator in the previous editions.

If he had to limit his professional bookcase to a single volume, Professor Charles du V Florey, the former president of the IEA, would choose to keep A Dictionary…. I argue that anybody among us—epidemiologists and would-be epidemiologists (hopefully with a larger shelf)—should also have a copy of this book at hand for frequent consultation.

The collective effort gathered in its making is impressive. Miquel Porta has built over the previously crafted editions, and has relied on the support of a wide network of professionals to update each entry and to expand the selection of subjects. The Journal of Epidemiology and Community Health joined the initiative by publishing a call for submissions.7 Items already selected from the previous edition have been revised and updated; several new items have been added. As a result, the fifth edition of A Dictionary… performs normative and informative functions: you will be informed on important matters and instructed on how to proceed in the epidemiological field. Readers with different needs and anxieties with knowledge will find straightforward writing, authoritative definitions and pertinent bibliographical references.

How to differentiate a rate from a ratio, incidence from prevalence, confounding from intervening variables, type I from type II error? How to appraise emerging themes in the epidemiological literature such as genetic polymorphisms and Bayesian statistics? Key methodological issues such as meta-analysis, multilevel analysis and regression models: the list solely enrols a small sample of possible searches. The selection of issues was broad in scope; intelligent and synthetic writing contemplated from the easier to the more intricate subjects.

You may want to update conceptual and methodological issues relevant to your teaching and research activities, to resolve doubts or to confirm an impression. You may want to check on terminology, fulfil curiosities or learn about topics unrelated to your preferential themes. You may be a professional applied to other health specialities, an undergraduate or a high school student. Several users will meet their needs by consulting A Dictionary…; even those who aimlessly scan the text may find some valuable insight. While it will not resolve all your needs in the epidemiological field, it surely provides enough substance to build on—a very good start or ammunition for more comprehensive searches.

Miquel Porta dealt with the challenge of preparing reader-friendly texts on a wide range of subjects, which will satisfy both a beginner and an experienced epidemiologist. He seems to have transposed Occam’s razor (see the correspondent entry: “the philosophical principle of parsimony… assumptions to explain a phenomenon must not be multiplied beyond necessity…”)6 to the writing of the book. If I may indulge in self-testimony, I found my teenage daughter consulting the book and it motivated a conversation on subjects so dear to me…. Arousing the interest of the young for a speciality admittedly perceived as difficult by adolescents; as goes the popular saying, this is priceless!

“Epidemiology is the study of the occurrence and distribution of health-related states or events in specified populations, including the study of the determinants influencing such states, and the application of this knowledge to control the health problems”.6 The definition has matured over the years and presents slight modifications from its previous formulation in the fourth edition. The entry for “Epidemiology” expands the conceptualisation of terms comprised in the definition and includes historical aspects. In subsequent years, this definition will be the benchmark of the discipline, until Miquel Porta and his collaborators eventually prepare a further edition to meet the new needs that the future may bring forth. I dare to guess that the prospective sixth edition of A Dictionary… will have an online dynamic interface interacting with the hard copy. I also dare to guess that it will include a new entry for A Dictionary of Epidemiology, whose importance to the professional field will surely have earned it.


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  • Competing interests: None.

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