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926 words

When health becomes a risky business

7 August 2017

Books | Epidemiologist Geoffrey Kabat helps steer us through the claims and counter claims


Meriel Jane Waissman/iStockphoto

Meriel Jane Waissman/iStockphoto

Getting Risk Right: Understanding the Science of Elusive Health Risks
By Geoffrey C. Kabat | Columbia University Press | $66 | 272 pp

Almost all the choices made by doctors and patients involve judging risks – the risks of particular treatments versus the benefits, and those risks or benefits against the likely impact of alternative options. Geoffrey Kabat makes the bold claim that this book will help us to get these risks “right.” He assesses a series of health risks and also gives some insight into wider issues of riskiness.

In a sense, we learn to assess risk at an early age. We grow to understand what is “too risky,” what is not. Decision-makers, whether they’re in government or industry, balance risk and reward. Most corporations – both for profit and not-for-profit – now have board committees with the word “risk” in their name, which have the role of assessing risk and determining appropriate ways of responding.

Yet, despite the ubiquitous nature of risk, and its importance, most of us are woefully underprepared to assess it. We haven’t absorbed risk concepts well and are easily misled by the way risks are presented to us.

A day rarely goes by, for instance, without a politician talking up the risks of terrorism, and promising that this or that favoured policy will reduce them. We’re then exposed to growing amounts of “blue tape” – measures designed to reduce the risk of terrorism incidents or their consequences. Rarely have these been subjected to any form of evaluation other than political calculus. Other forms of risk – from environmental pollutants, traffic crashes, ice, alcohol and so on – are evaluated quite differently by politicians and the public.

Perhaps journalists ought to have three standard questions about policy announcements purporting to be about risk: what is the current level of risk you are trying to prevent or reduce, in terms of potential lives lost per annum? What will be the rate once these measures are implemented? And what will be the total annual cost of these measures, including the cost of inconvenience to the public? These are the critical risk questions, but are unfortunately not clearly highlighted in Getting Risk Right.

Kabat uses his expertise as a New York-based cancer epidemiologist to discuss risk in a relatively non-technical way. His book consists of two loosely connected sections: the first few chapters are a primer on risk; the remaining chapters recount how some hazards or causes of disease were uncovered and examine a series of controversies about health risks and their treatment.

The early chapters are designed to make us better consumers of risk information. They teach us (gently) about the epidemiological methods used to identify and measure risk, introducing us to case-control studies, which yield the odds ratios revealed by differences in exposure to hazards, and cohort studies, which yield the relative risk of consequences for those exposed and those not.

Kabat goes on to highlight the complexity of measuring risk in the real world. The controlled conditions of the laboratory – where there is usually only a single exposure under study – are a long way from the world of multiple exposures and multiple outcomes, with any one exposure potentially leading to multiple outcomes.

A new environmental hazard emerges seemingly every day, but many of these may be less about alerting the public to a meaningful risk than about getting a new paper published to increase the likelihood of getting a grant. Kabat does a valuable service here by citing real-world examples in a provocatively named section, “Why most research results are false.”

The primer part of the book also highlights some of the media- and quackery-induced scares of recent decades and provides a useful list of the key factors to be borne in mind in interpreting the “studies” that lead to those scares: misunderstandings about the difference between association and causation, the possiblity of false positives, and publication bias. Quack scientists can quickly accumulate citations and gain media exposure, at the public’s cost, to benefit their careers. The presentation of risks can easily mislead: an increase from one in a billion to two in a billion is indeed “a doubling” in risk, but putting it that way can be highly misleading.

With this background, the remainder of Getting Risk Right is a set of case studies, including an examination of the controversy over mobile phones and brain cancer and the science of a herb that was found to increase the risk of cancer. These read like detective stories, looking at the epidemiological and laboratory studies involved in testing the risks. Again, these chapters are well-written and interesting. The book also includes a helpful glossary.

Despite its manifold strengths – including clear writing and being on the side of the angels in aiming to help the reader to be a sceptical consumer of the latest gee-whiz epidemiological or clinical study – the book left me somewhat dissatisfied. Kabat only lightly traverses some of the key policy issues involved in risk in healthcare. The most contested of these, the controversy over screening for breast and prostate cancer, are barely mentioned. Nor does he explore society’s – or, more accurately, policy-makers’ – different levels of risk tolerance in different circumstances, even within the health sector.

Understanding risk measurement and its presentation, and the factors which influence the way risk is presented, are important. Kabat’s book makes a useful initial contribution, and the early chapters, in particular, should be essential reading for journalists and others who report so breathlessly about risk information arising from new research findings. For the rest of us, it is a tantalising start to “understanding the science of elusive health risks” that fails to deliver fully on that promise. •

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