Epidemiology, Biostatistics, and Preventive Medicine Review By ...

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792 Book Reviews on needs assessment, service planning, and evaluation, including economics. Part 2 comprises 12 chapters on selected diseases classified ...
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Book Reviews

on needs assessment, service planning, and evaluation, including economics. Part 2 comprises 12 chapters on selected diseases classified by method of transmission, an important though not necessarily critical determinant of method of control. Some diseases are most effectively controlled, for example, by methods that focus on targeting the reservoir of the agent or on enhancing host resistance. The author's stated logic for his selection of specific diseases to cover is their importance or illustrative value. This results in some curious inclusions and exclusions: for example, the inclusion of the common cold, which is common but relatively unimportant, and the exclusion of Legionella and Mycoplasma pneumonias, which are less common but more important; and the inclusion of smallpox, long since eradicated, but the exclusion of Creutzfeldt-Jakob disease, a rare but critically important emerging infection. The detail in which specific infections are covered varies greatly, and in some cases with little obvious justification. Why, for example, is leprosy, an important but declining disease, accorded a whole chapter, while tuberculosis, arguably still the "captain of the men of death" in developing countries, is actually given less space? Similarly, the various hepatitis viruses are all dealt with in two pages, while there are eight pages devoted to plague. A particularly disappointing feature of this part of the book is the fact that, notwithstanding the intention expressed in the introduction, considerable space is given to the diagnosis

and treatment of individual infections (though often too little to be adequate for clinical management purposes), while there is little attempt to derive integrated control policies for the groups of epidemiologically related infections. A section at the end of each chapter that attempted to draw out common control themes would be useful. The above criticisms, while significant, should not detract from the fact that this book provides excellent descriptions of many of the world's most important communicable diseases (the clear and informative illustrations are a particularly valuable feature) and vital information on the principles and practice of control. In future editions, however—bearing in mind the goal he set for himself, which gives the book its unique attraction—the author may wish to reconsider the balance and, to some extent, the orientation of his material. This said, the book as it stands will be welcomed as an informative and practical guide by doctors and other health workers in warm climates and impoverished countries where communicable diseases remain rampant. David Miller Division of Public Health Sciences United Medical and Dental Schools of Guy's and St. Thomas's Hospitals University of London Lambeth Palace Road London SE1 7EH, England

Epidemiology, Biostatistics, and Preventive Medicine Review By David L. Katz ISBN 0-7216-4084-2. W.B. Saunders Company, Philadelphia, Pennsylvania (Telephone: 800-545-2522, FAX: 215238-7883), 1997, 241 pp., $19.95

Clinical Epidemiology: The Study of the Outcome of Illness. Second Edition By Noel S. Weiss ISBN 0-19-511026-9. Oxford University Press, New York, New York (Telephone: 212-726-6000, FAX: 212-7252972), 1996, 163 pp., $29.50

These two primers in epidemiology are similar in function, though each fills a very different niche. Epidemiology, Biostatistics, and Preventive Medicine Review, by David Katz, attempts to address a broad range of topics. Covering a large breadth of material with adequate depth is the bane of any review book; accomplishing both of these tasks well is akin to writing a new textbook. An effective review book should stimulate comprehensive recall of previously mastered

concepts while providing the user with an intuitive framework with which to organize and systematize the information. No review book is meant to stand alone, apart from a comprehensive textbook. This book is no exception; its companion text (1) is noted in the preface. The book's stated audience is anyone preparing for the United States Medical Licensing Examination. The health practitioner who desires to refresh his or her Am J Epidemiol

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knowledge of basic concepts in epidemiology, biostatistics, and preventive medicine will also find this book useful. Katz states in the preface that preparing study material on biostatistics, epidemiology, and preventive medicine for persons taking a standardized test is "tedious at best, and at worst oppressive." He thus attempts to make the endeavor more interesting, if not downright fun. He uses several techniques rather successfully to accomplish this end. Loss of some finer points and of appreciation for a subject's richness is the price paid in some cases. Overall, Katz's book should make test preparation less arduous for the average medical student. Katz divides the book into four principal sections. Section I, "Epidemiology," discusses epidemiologic approaches, data sources, surveillance, outbreak investigation, and research methods. Section n, "Biostatistics," describes variation in data, improving clinical decision-making, statistical inference, and various analytical techniques. Section HI, "Preventive Medicine and Public Health," discusses primary, secondary, and tertiary prevention and basic public health concepts, and touches on some broader sociopolitical issues. The section ends with a brief outline of medical care policy and financing. Section IV consists of a practice examination, a glossary, and various appendices. Each section contains approximately 6 - 8 chapters. Each chapter addresses several concepts grouped together by a common theme. For example, the chapter on epidemiologic surveillance and outbreak investigation includes discussions on types of surveillance, seasonal variation, the term "epidemic" versus "endemic," investigation procedures, and laboratory use. Each chapter ends with several review questions that help to reinforce retention of the material presented. Comprehensive answers are provided. Katz did an excellent job of making these questions fun and interesting to read; many of them contain zany scenarios that only superficially resemble reality. A few major issues receive curiously minimal discussion. Herd immunity is described as resulting "when a vaccine not only prevents the vaccinated from contracting the disease but also prevents him or her from spreading the disease" (page 3). While this is a component concept of herd immunity, routine vaccination independent of herd immunity may prevent a vaccinated individual from spreading the disease agent. For a thorough review of important topics such as herd immunity, reference to one or more major textbooks is essential. One topic that is problematic for many students and is often found on standardized examinations is rate standardization. Katz presents both direct and indirect standardization techniques clearly and thoroughly. Am J Epidemiol

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Most readers will find similarly adequate presentations of other topics commonly found on standardized examinations as well. This is one of the best review books available for the medical student who is preparing to take the United States Medical Licensing Examination or another standardized examination. However, several significant topics are covered superficially. For that reason, the Master of Public Health student or public health professional will most likely find the book of limited utility. The second edition of Clinical Epidemiology: The Study of the Outcome of Illness is also a primer in epidemiology. The author, Noel Weiss, wrote this book for the practicing clinician. Unlike the Katz book, which is intended for students, this book attempts to prepare the clinician for either conducting or understanding epidemiologic research. This is a much taller order, and a basic understanding of epidemiology and biostatistics on the part of the reader is assumed. The book grapples with the issue of how well the practicing clinician is prepared for understanding population-based medicine. Although epidemiology is now taught in virtually all medical schools, it does not form the basis of the curriculum. Medical school education is based on the patient-problem paradigm, as perhaps it should be. The trouble occurs when a well-trained clinician attempts to delve into population-based concepts in medical practice, either by applying them to the treatment of a patient or by conducting clinically based research. A single textbook, no matter how well written, will probably never solve this dilemma. Ultimately, the medical student needs to be familiarized early in his or her education with population-based medicine. For the clinician who is already trained and practicing, this book, along with several others available, may help to bridge the gap. The second edition contains updated material, and a few new topics, such as decision analysis, have been added. The book contains seven chapters, an appendix, and a brief index. The opening chapter introduces the concept of clinical epidemiology, covering its definition, uses, and theory, and gives examples of how it relates to the daily practice of medicine. The next two chapters thoroughly discuss the use of diagnostic and screening tests. The ability of a screening test to predict adverse outcomes of illness is addressed first. Concepts such as sensitivity, specificity, and predictive value are introduced. The presentation of these concepts is complete but brief. For those needing more of a review of these topics, a book such as the one by Katz might help to refresh memory. The discussion of screening tests then turns from predicting disease out-

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come to improving disease outcome. Basic study designs are introduced. The remainder of the book takes the reader through very detailed discussions of therapeutic efficacy as it relates to randomized and nonrandomized studies, and therapeutic safety. The final chapter discusses the natural history of disease, and covers topics such as causal relations and study selection. Each chapter ends with a few pertinent review questions and a very complete reference list. The appendix provides conceptual tools for conducting research, such as methods for estimating the number of subjects needed in a study. Unfortunately, while this book is an extremely thorough, comprehensive work on the subject of clinical epidemiology, parts of it are ponderous and almost unreadable. Chapter 3 begins with an 88-word sentence: Ordering or performing a diagnostic or screening test can reduce the frequency of disease occurrence (or progression, or complications) only if the test can (a) detect the condition or abnormality before it or its consequences would otherwise be evident, and (b) lead to treatment that is more effective when administered soon after the time of testing than if it were to be administered either later in the natural history of the condition, when the condition or abnormality would become evident in the absence of testing, or not administered at all. This verbose writing style is representative of the remaining text. Though the book targets a clinician audience, it is not clinician-friendly. Many clinicians may not have time to read such a wordy book in one sitting. A clinician-friendly book should lend itself well to the "bolus" reading, as well as to the "continuous infusion" technique. Short, concise sentences that each convey a specific point would help to achieve this end. While the logical flow of the book is certainly not flawed, a more intuitive organization of the material would greatly assist the reader.

A few changes would most likely make this book an unbeatable resource. Clinicians think about one patient at a time, from presentation to diagnosis to treatment options and outcomes. An easy-to-understand book tells a story. Perhaps the book should begin by discussing the natural history of disease and how epidemiologic methods help researchers to sort out these various issues. It could next cover the relation between epidemiology and diagnosis. The topic of interventions could then be introduced. How does a drug or treatment move from the hypothesis stage to being the standard of care? How would one carry out a study to get a drug or procedure approved? Clinicians are adult learners. The material should be organized and presented so that there is an existing framework in which to integrate the new information. The first and second editions of the book are noticeably different. The first edition was easier to read, and sentences were kept to a manageable length. The second edition clearly needs additional editing. If an intuitive presentation and good copy writing were combined with the author's expertise and wisdom, this book could be considerably more valuable.

REFERENCE 1. Jekel JF, Elmore JG, Katz DL. Epidemiology, biostatistics, and preventive medicine. Philadelphia, PA: WB Saunders Company, 1996. E. Ronald Hale

Department of Health Policy and Management School of Hygiene and Public Health The Johns Hopkins University Baltimore, MD 21205

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