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Blackwell Science, LtdOxford, UKPPEPaediatric and Perinatal Epidemiology1365-3016Blackwell Publishing Ltd, 200317

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Book Review

Book reviewsBook reviews

Book reviews

Eating Disorders and Obesity: a Comprehensive Handbook. 2nd edn.

Edited by C. Fairburn and K. D. Brownell.

New York: Guilford Press, 2002, pp. 623, $65.00. ISBN: 1-57230-688-2

This handbook is written mainly for an audience ofclinicians and researchers working in the field of eatingdisorders and obesity. However, it can be appealingalso to clinicians working in the field of endocrinology,nutrition and childhood disorders.

This second edition of the book considers both topicsfrom a cross-discipline perspective, spanning frommolecular genetics to subjects such as physiology,pharmacology and epidemiology. It tries to provide acomprehensive account of all eating disorders acrossthe lifespan and of obesity, bridging the gap betweenthe two fields. It also includes topics that are relevantto both ends of the spectrum of weight disorders.

The book is divided into three sections: the founda-tion, eating disorders and obesity. It consists of 112chapters written by well-known international expertsin the field. Each chapter aims to provide a succinctbut comprehensive review of the literature on a partic-ular topic. The chapters are somewhat short, andalthough probably fulfilling their aim, I found it quitefrustrating when, at times, having become very inter-ested in a topic and wanting to know more about it, Ihad already reached the end of the chapter. The lackof in-text references makes it even more difficult to goback to an original article to pursue more information.There is, however, a list of suggested reading at the endof each chapter to supplement this. The book thereforeprobably suits more a reader who wants brief andrelevant information on a very specific topic in thefield.

The first part of the book focuses on the biology andphysiology, psychological and social aspects of dieting,body weight and energy balance. It has a developmen-tal, but also an ontogenetic approach and gives anaccount of all the latest developments in animal andhuman research on the physiology and biology of

weight regulation and food intake. The section onsocial and psychological aspects of dieting is very wellintegrated with the biological aspects discussed in thefirst 12 chapters and includes very relevant topics suchas the acquisition of eating patterns in childhood, andthe stigma and discrimination associated with obesity.Altogether this part of the book is probably more rel-evant to researchers. However, the chapters on foodpreferences and eating patterns in children and on theprevalence of dieting across the lifespan provide usefulinformation for paediatricians and for anyone with aninterest in epidemiology.

The following section covers very thoroughly all eat-ing disorders, aspects relating to aetiology and treat-ment. Again several facets of eating disorders areexplored, including genetics, neurophysiology, psy-chology and social aspects of these disorders. Two veryinteresting chapters in this section are devoted to theoften-neglected issues of families of eating disorderpatients and child-rearing practices of parents with aneating disorder.

There are also four chapters on the medical andphysical complications of eating disorders, which area good overview for general practitioners, paediatri-cians and physicians who may have contact with eat-ing disorder patients.

The third and largest part focuses on obesity. Thispart is well structured and examines several medical,psychological and social aspects of this 20th centuryepidemic. It is divided into three sections, coveringclinical features, epidemiology, medical complications,and treatment and prevention strategies. It has a goodsection on the epidemiology of obesity, including achapter on the international and global view of obesityand on minority populations.

The section on treatment and prevention is verygood, detailing different treatment options. Four orfive chapters are devoted to diets and commercialweight-loss programmes; these also include recom-mendations for clinicians and a detailed evaluation ofdifferent existing treatments for obesity. Psychological

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as well as pharmacological and surgical options arereviewed, and new options for the future arediscussed.

Several chapters focus on childhood, in all the dif-ferent sections, which can be of relevance for paedia-tricians, nutritionists, nurses and anyone working inthe field of obesity.

This book on the whole achieves its aim of compre-hensively reviewing several aspects of eating disordersand obesity research and practice. The way in which itdoes so, however, may suit some readers more thanothers. Clinicians and researchers who want a specificanswer to a specific question on eating disorders orobesity will certainly find this book useful. It is a goodreference book for general practitioners and commu-nity paediatricians or anyone who works at the inter-face between child health and more specialisedsettings in the fields of eating disorders or obesity.Epidemiologists, however, are likely to want moredetailed evidence for the statements made.

NADIA MICALI

Medical Statistics Made Clear – An Introduction to Basic Concepts.

By Ashis Bannerjee.

London: The Royal Society of Medicine Press, 2003, pp. 137, £19.95. ISBN 1-85315-544-6

At first glance, this looks like a book to fill a void inthe literature. I find Brian Everitt’s

Dictionary of Statis-tics

and John Last’s

A Dictionary of Epidemiology

veryhelpful but I haven’t found a book that covers all thebrief descriptions and definitions of the variety of top-ics that come under the umbrella of ‘medical statistics’,despite there being a number of excellent textbooks onthe subject. Indeed it is an ambitious project to writesuch a book. Firstly, the scope of statistical techniqueshas expanded rapidly over recent years, facilitated bythe increase in computing power (Bayesian

MCMC

methods, for example, are being used to solve prob-lems formerly considered to be intractable) and, sec-ondly, a book on ‘medical’ statistics should includesuch clinical applications as medical diagnosis, clinicaltrials and epidemiology.

I started reading this book with eager anticipationbut realised very quickly that there were problemswith it. The introduction indicated that mathematicaldetail was going to be kept to a minimum. Whilst Iapplaud this aim, it is difficult to accomplish this with-

out making the text example-based. Without examples,a text must be accurate, clear and concise, and followa series of consistent logical progressions. The bookunfortunately fails in all these areas, with content rang-ing from being vague, imprecise or contentious tobeing downright inaccurate, and with a logical flowthat can be discontinuous and difficult to follow.

Of major concern were the inaccuracies. These werebeyond simple errors of proof reading and were soprolific in the topics that were familiar to me that I laterbecame mistrustful of topics that were unfamiliar. Onthe second line of the very first page, for example, weare told that the

ANOVA

is used for ‘assessing the con-tribution of more than two independent categoricalvariables’. An immediate counterexample to this, ofcourse, would be a one-way

ANOVA

. On the same pagewe are told a ‘binary variable’ is ‘two mutually exclu-sive variables’. Such errors abound but more seriousones follow later. In order to compare two groups(page 54) we are told to use a

t

-test with (n-1) degreesof freedom. Later we are told that the magnitude of

t

depends on the significance level (top of page 60).Later still (page 88) we are told that a

P

-value is ‘thesmallest level of significance at which the null hypoth-esis can be rejected’.

The logical flow of the text I find perplexing. Onpage 30, for example, we are given ‘requisites for a

Z

-test’, without being told what a

Z

-test is. In a list ofnon-parametric tests to compare two independentsamples (page 53) we find ‘Wilcoxon rank sum test:paired samples’. Immediately after sections on ‘oddsratios’ and ‘relative risks’ (pages 74 and 75) we find asection on likelihood ratios as used to evaluate screen-ing tests, although a formal description of screeningtests does not appear until page 82 (as Box 30). Adescription of Venn diagrams (‘to provide pictorialrepresentation of the extent to which two or moreevents are mutually inclusive or exclusive’) is given inthe middle of a section on the Multiplication Probabil-ity Rule (page 93). There is confusion between likeli-hood and likelihood ratio (page 95). Moving ontoconfidence intervals, the text correctly states these canbe constructed for most common statistical estimators(page 89) but only the method for a simple mean isshown (Box 34) and this is not made clear. Similarly,for the general description of Analysis of Variance (Box100 on page 100) the very specific one-way

ANOVA

with equal group sizes is shown. On the next page(page 101) multifactor

ANOVA

and multivariate

ANOVA

(

MANOVA

) have been confused. The

CUSUM

statistic

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was defined originally for process control of continu-ous variable and I find the definition on page 116(given for a binary variable) perplexing; the importantfeature of a

CUSUM

chart is that a small change in levelin the variable is signalled by a change in slope of the

CUSUM

.The series of numbered ‘Boxes’ are used throughout

to give

ad hoc

illustrations and equations but these arenot referenced from the text. The equations given inthe boxes are often not fully explained and some areinaccurate.

Bullet points are also used extensively in the text,but not to good effect; I have found lists that are repet-itive or contain contradictory, irrelevant or incompleteinformation. Many statements are unhelpfully vague;the description of an ‘enriched enrolment design’(page 76), for example, left me unclear as to how onemight utilise one.

There are other assertions made which, although nottechnically incorrect, could still be contentious. It maybe argued that one should not use visual display ofdata ‘to suggest the appropriate statistical analysis’(page 11) but rather one should decide on the methodof analysis beforehand. Defining outliers to be values‘beyond the whisker <of a Box plot> but less than threeinterquartile ranges from the box edges’ (page 15) is acriterion used by some statistical software but not oth-ers. One could argue that stratification should be afeature of a trial study design rather than just in itsanalysis (page 79). Some contend that the term‘multivariate’ should only be reserved for the casewhere there are several outcomes or target values, pre-ferring the term ‘multivariable’ for multiple regressionand logistic regression in which there is only one (page107).

I have highlighted only a fraction of the problemswith this book. In summary,

Medical Statistics MadeClear

is anything but ‘clear’. I would not recommendto any of my medical colleagues and, in particular,would not recommend it to students who would justbe misled by it.

LINDA HUNT

Establishing a Dialogue on Risks From Electromagnetic Fields.

By the World Health Organization.

Geneva: WHO, 2002, pp. 66, £13, US$18. ISBN 92-4-1545712.

This is a small booklet with a long gestation of 5 or6 years and an impressive list of parents and guard-

ians. On the electromagnetic field topic it has threesections – the present evidence on public health, pub-lic perception, and the present situation on guidelinesand policies. It appears to be intended not for the sci-entist but, as stated, for ‘decision makers’ and ‘publicofficials, private groups and non-governmental orga-nisations’. Nevertheless, the subject of electromag-netic fields is an example of a scare story that hasevolved over the years and been fuelled by theadvent of widespread uncontrolled development andimplementation of new technologies, currently in theshape of mobile phones and associated cell phonemasts.

A short while ago it was only the magnetic field thatraised public ire. The anxieties have polarised onto thetwo modalities of power frequencies, particularlyfrom high voltage power lines, and onto the micro-waves associated with mobile phones. Biologicallythese are so different as to present real problems ofincluding them under one title. However, they dohave one thing in common and that is the perceivedeffects on children in the form of leukaemia associatedwith power lines (magnetic fields) and, with less evi-dence, the association with radio masts. Fashionschange. For example, the previous public anxietyabout microwave cookers that jammed the NationalRadiological Protection Board switchboard in the UKis no longer an issue except with the extremist. Suchdevices are accepted as safe and an indispensable partof life with no action needed by government or indus-try. It is possible that the recent acknowledgement ofmagnetic fields as ‘possibly carcinogenic to humans’(IARC classification 2B) has actually reduced the pub-lic risk perception about power lines, particularlysince the risk is now in the same class as coffee. Thisis addressed in this book.

The difficulty with addressing the public on theissues of power lines or mobile phones is that there arevisible (e.g. pylons, masts, phones) elements and invis-ible (magnetic and electric fields) elements associatedwith those who derive benefit in contrast with thosewho do not perceive benefit. This booklet handles thiswell in explaining familiar and unfamiliar technology,voluntary vs. involuntary exposure, the dreaded ornot-dreaded outcomes, direct and indirect benefits,and fair vs. unfair exposure. The reader using this bookas a guideline to communicating risk perception is leftin no doubt about the pitfalls of this task.

The booklet’s advice on managing the process ofcommunication suggests an ideal scenario not, in my

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experience, adhered to by industry wanting to imple-ment something they suspect the public might not like!Communication, information and dialogue before set-ting policies, for example for a new power line or cellphone mast, is the ideal but, in practice, likely to leadto a ‘crisis wave’ which can be difficult to handle. Thisprocess is well explained. The general public, itacknowledges, is better informed and better educatedand fairly fuelled by the media to take part in decisionmaking. Ironically, the media can be used to goodeffect to increase public awareness of both sides ofthe risk communication arguments. Unfortunately thisrelies on the scruples of journalists who tend to claimit is the editor who designs the headlines, howeverobjective the story.

‘What’ and ‘how’ to communicate on the electro-magnetic field issue is excellently handled withgood advice on neither over-complicating or over-simplifying the issues and the evidence. Whilst

acknowledging that distorted science can be put for-ward by what it coyly calls ‘so-called experts’ (i.e.cranks who may have professorial status), it has nosuggestions about countering this other than by rollingout opinions of panels of independent experts. This isa difficult area and fraught with the need to keep suchpanels independent of both politicians (least trusted)and industry (profit motive).

Value for money? Infinite, since the whole bookletcan be downloaded free (from http://www.who.int/peh-emf/publications/EMF_Risk_ALL.pdf), but thedefinition is not as good as the real thing with its highquality paper, very attractive and artistic graphics andcolour-coded sections that my printer could not repro-duce. A useful read and a good model for handlinghealth scares that industry cynically accuses scientistsof turning into air tickets to conferences.

ALAN PREECE