Views And Reviews

Basic Epidemiology

BMJ 1994; 308 doi: https://doi.org/10.1136/bmj.308.6926.483 (Published 12 February 1994) Cite this as: BMJ 1994;308:483
  1. G D Smith

    Epidemiological studies have a high profile in the popular media as well as in serious medical journals. Media attention often accompanies studies that seem to contribute to the major goal of epidemiology identified in this book: “Discovering the causes of disease.” That a certain weariness is setting in, however, is illustrated by a recent report in the Guardian. Under the headline “Doctors add tea to a bewildering list of what is good for you” it is reported that “Doctors in Holland have found that a cup of tea seems to reduce the risk of heart attack.” The sceptics are reminded that people “have been told consistently to reduce alcohol intake, and then that red wine could be good for the heart.” Studies that bewilder the health conscious have led commentators to write articles with titles like “The poverty of epidemiology” and “Epidemiology contributes to iatrogenesis.”

    It can be argued that this situation is more a product of a superficial approach to, or ignorance of, epidemiology than of epidemiology itself. Epidemiological methods, when applied carefully and self critically, offer a way of assessing a population's health, developing beneficial public health schemes, and evaluating health technology and health services.

    Covering the scope of theoretical and applied epidemiology in a brief book is a daunting task, which this World Health Organisation manual manages commendably. Assuming little or no knowledge of the subject, it sketches the history and development of epidemiology; discusses the issues that arise in measuring health and disease; describes the design of epidemiological studies; outlines basic statistical methods; and then moves through the sequence of identifying causes of disease at the population and individual level, determining the effectiveness and efficiency of preventive strategies, and applying epidemiological principles in health services planning and health policy. Separate chapters are devoted to environmental and occupational epidemiology, communicable disease epidemiology, clinical epidemiology, and continuing education in epidemiology.

    Inevitably, to cover these topics in only 170 pages necessitates a basic approach - as the book's title implies. In places this is unsatisfactory. Thus the introduction to statistics emphasises significance testing at the expense of effect size and estimating confidence intervals. The section on “the control of confounding” presents an overoptimistic view of the possibility of this and fails to underline the need to consider the problem early in the design of the study. Finally, the discussion of the development of healthy public policy is Panglossian in its failure to acknowledge the degree to which such efforts can be hijacked and absorbed by commercial and political interests.

    Exactly who will find this book useful is unclear. Though it offers an outline of the various strands included under the term “epidemiology,” for medical and paramedical students even 170 pages of these principles are likely to be too much. In this case teachers probably do better to resist the temptation to cover the whole domain of occupational epidemiology and provide instead a detailed and interesting example of the epidemiological aspects of a particular occupational health problem. The same considerations apply to many of the other topics dealt with in the book. For students more directly concerned with public health, on the other hand, going straight to a more detailed coverage of epidemiology would probably be advantageous.

    Finally, the most immediate aspect of the book must be mentioned: the unpleasant chemical odour emitting from its pages. I checked other copies, including some in another country, and found that all of them shared this feature. Other readers remarked on the smell and agreed that it was grim. Epidemiology has enough of an image problem without punishing those seeking an introduction to the subject.

    Figure1

    Isotope scanning is valuable in several types of metabolic bone disease. The Picture shows ectopic calcification in the lungs in a patient with renal osteodystrophy; a transplanted kidney is apparent in the left pelvis. From Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism (2nd edn, Raven, $40.50, ISBN 0-7817-0083-3), an official publication of the American Society for Bone and Mineral Research

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