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Book Reviews
Asthma Epidemiology: Principles and Methods By Neil Pearce, Richard Beasley, Carl Burgess and Julian Crane New York: Oxford University Press, 1998; ISBN 0-19-508016-5; $73.95 (CAN) Overall, this is a very good textbook on the epidemiology of asthma, with only a few omissions of content. The authors come from the Wellington Asthma Research Group of Wellington, New Zealand. Readers familiar with the historical epidemiology of asthma will recall the many published studies of the sharp rises in asthma mortality in New Zealand-first in the 1960s, then the 1980s-and the epidemiologic identification of the most likely causes (more about that below). The authors themselves are well published in the field, and they are cited in this textbook along with many other well-known authors of epidemiologic studies of asthma in the Western world. The book is not too long to tackle: only 260 pages, including references. Although this reviewer read it from beginning to end, the book can be used as a reference because most of the chapters can be read independently as needed. Consisting of seven chapters (excluding the Introduction), the book is organized into three parts: "Basic Principles of Asthma Epidemiology," "Asthma Morbidity" and "Asthma Mortality." Intertwined in the book are the two basic themes of asthma epidemiology. The first is the epidemiologic evidence that answers questions like the following: Is asthma prevalence still rising? What were the causes of the dramatic increases in mortality in the previous two decades? What is the evidence about the risk factors for asthma, including genetic and early life exposures, in causing the disorder? The second theme is that of epidemiologic methods: the strengths and weaknesses of various study designs, definitions of terms, measurement issues, control of bias and confounding, and so on. These issues are, of course, generic to all epidemiologic research, but the authors here provide many examples pertinent to the study of asthma. The book starts with a short but interesting history of the recognition of the asthmatic condition in ancient times. The word asthma came from the Greek word for "panting." The Introduction summarizes some international definitions of asthma, but provides only a brief description of the pathophysiology, clinical features and management of the disease. In subsequent chapters, the pathophysiologic and clinical aspects of asthma (including treatment) are discussed only in the context of epidemiologic studies. The reader who is not already familiar with the pathophysiology and clinical features may have a little more difficulty understanding the significance of the studies, aside from methodological issues. Even a few illustrations (of the lungs and bronchi, of inflammatory cells, etc.) could make the book more accessible to the novice reader of asthma epidemiology. One would not expect colourful Frank Netter-like creations, but some small illustrations of spirometers, peak flow meters and inhaler medications might facilitate the understanding of the many epidemiologic studies concerning diagnostic and treatment issues for asthma. However, the authors provide excellent discussions of epidemiologic study design and measurement issues in chapters 2 and 3. Measures of incidence and prevalence, selection of cases and controls, issues of precision, validity, confounding, bias and effect modification ... these are all covered comprehensively but succinctly. Epidemiologic methods are also covered well in Chapter 4, "Measuring Asthma Prevalence." The authors "get specific" when discussing asthma symptom questionnaires, such as the large-scale European Community Respiratory Health Survey (ECRHS) and the International Study of Asthma and Allergies in Childhood (ISAAC). The pros and cons of using physiologic measures such as bronchial hyperresponsiveness are also addressed. Another minor "deficiency" in this book is the relative brevity concerning the evidence about the recent international trends in asthma prevalence and incidence. While the evidence for asthma mortality trends merits the two full (and very good) chapters at the end of the book, the evidence for asthma prevalence trends are only briefly discussed in the Introduction, in Chapter 4 (pp 77-79) and on page 213 (in the context of whether increased prevalence or incidence was behind the increased mortality rates-short answer: not significantly). Chapter 6 thoroughly examines both epidemiologic evidence and methods regarding the risk factors for asthma. Risk factors are broadly defined to include everything from genetics and demographics to atopy, allergens, air pollution, occupational exposures (sometimes omitted in asthma epidemiology literature) and even diet. The authors provide many good examples from the published literature. They not only mention study results, but also venture reasoned opinions on the overall strength of the evidence concerning certain risk factors. As already mentioned, the last two chapters (7 and 8) review the issues of asthma mortality, both the evidence about recent international trends and the methods behind the different kinds of epidemiologic studies. Chapter 7, in particular, reads like a good "mini-detective story" about determining the causes of the epidemics of asthma mortality-first in the 1960s, then the late 1970s to the 1980s-in countries such as New Zealand, Australia, Great Britain, the United States and Canada (e.g. the studies in Saskatchewan by Spitzer et al.). The main culprit (for those of you who still don't know) was the introduction (and presumed overuse) of inhaled beta-2 agonists such as isoproterenol (the "Forte" preparation) and fenoterol. Another bonus of this book is that each chapter closes with a good one-paragraph summary. Somewhat unfortunately, however, the book ends abruptly with the summary of the last chapter. A "closing" chapter for the book, perhaps about future epidemiologic research needs for asthma, would have been desirable. It would also have been useful to have a chapter summarizing the state of public health surveillance of asthma, including the kinds and sources of mortality and morbidity data available in several major countries as examples. I think that this is part of asthma epidemiology. But these are relatively minor quibbles about a fine textbook overall. The most suitable audiences, according to the authors, would be "not only epidemiologists, but also respiratory physicians, allergists and pediatricians involved in asthma epidemiology." I would expand this to include graduate-level students and other clinical practitioners who wanted a good review of asthma epidemiology.
Edited by Ross C Brownson and Diana B Petitti New York: Oxford University Press, 1998; ISBN 0-19-511190-7; $73.50 (CAN) The last several years have seen the publication of a number of important epidemiology textbooks, such as the new edition of Modern Epidemiology.1 As a result, it was not clear to me that there was any need for a further basic epidemiology text. However, Applied Epidemiology is not a traditional epidemiology text. After a few brief introductory chapters on epidemiologic principles and methods, the book instead deals with the role of epidemiology in the practice of public health. This book should help fill a void in the training of many epidemiologists who receive rigorous training in epidemiologic methods but little or no training in public health, and it will be most useful to epidemiologists working in public health departments. The principle limitation of the book stems from its American perspective and the country-specific nature of public health practice. For example, differences in how health care is delivered in the United States versus Canada lessen the usefulness of the chapter on screening in the community to Canadian readers. The heterogeneous nature of US health care funding has meant that some sectors have embraced controversial screening strategies, such as mammography for women under age 50 and PSA screening for men, in contrast to the more conservative approach taken by the publicly funded health care system in Canada. The book should have discussed problems that result from situations in which those most likely to be screened may be those who least need to be screened, as well as the advantages of systematic screening versus ad hoc screening. The chapter on outbreak and cluster investigations could be stronger. Although Brownson (chapter author) acknowledges that the scientific value of community cluster investigation may be limited, he fails to fully explore the problems associated with these studies, such as those of post hoc reasoning, or to capture the skepticism that many feel for cluster investigations. The book also deals with a number of currently "hot" topics, such as outcomes research, measuring the quality of health care and cost-benefit analysis. Although written from a US regulatory point of view, the chapter on risk assessment is particularly interesting. Reference 1. Rothman KJ, Greenland S, eds. Modern epidemiology. 2nd ed. Philadelphia: Lippincott-Raven, 1998.
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Last Updated: 2002-10-22 |  |
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