Smart Health Choices E-Book

Les Irwig

• Herausgeber: Hammersmith Health Books
• Kategorie: Ratgeber
• Sprache: Englisch
• Veröffentlichungsjahr: 2013

Beschreibung

Smart Health Choices provides the tools for assessing health advice, whether it comes from a specialist, a general practitioner, a naturopath, the media, the internet of a friend. It shows you how to take an active role in your own healthcare, and how to make the best decisions for you and your loved ones, based on your personal preferences and the best available evidence.

Leseprobe

Smart Health Choices

Making sense of health advice

Professor Les Irwig Judy Irwig Dr Lyndal Trevena Melissa Sweet

Cartoons by Ron Tandberg

Copyright

First published as a print book in 2008 by Hammersmith Press Limited First published as a digital book in 2014 by Hammersmith Health Books, an imprint of Hammersmith Books Ltd 14 Greville Street, London EC1N 8SBwww.hammersmithbooks.co.uk

Reprinted 2014

All rights reserved. No part of this publication may be reproduced, stored in any retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publishers and copyright holder or in the case of reprographic reproduction in accordance with the terms of licences issued by the appropriate Reprographic Rights Organisation.

Disclaimer Whilst the advice and information in this book are believed to be true and accurate at the date of going to press, neither the author nor the publisher can accept any legal responsibility or liability for any errors or omissions that may be made.

British Library Cataloguing in Publication Data: A CIP record of this book is available from the British Library.

Print ISBN 978–1–905140–17–6 Ebook ISBN 978–1–781610–53–4

Commissioning Editor: Georgina Bentliff Copy editing by Jane Sugarman Designed by Julie Bennett Production by Path Projects Ltd Typeset by Phoenix Photosetting, Chatham, Kent, UK Printed and bound by TJ International Ltd, Padstow, Cornwall, UK Cover image: © Photolibrary Group

In loving memory of Andre Joffe 1964–1999 He touched the lives of so many people In so many extraordinary ways

Contents

Title PageDedicationCopyrightAbout the authorsBefore you read this bookAcknowledgementsDisclaimerPart I: Health advice can be harmful1 This book could save your life2 Be sceptical3 Bad evidence4 Don’t always rely on the expertsPart II: Your body, your choice5 Smart health choice essentials6 Choosing a practitioner or a hospitalPart III: Stories and studies7 An education in shopping8 The weakness of one9 The power of manyPart IV: Evaluating the evidence10 Judging which tests and treatments really work11 What makes you sick?Part V: Improving your healthcare12 Finding the best evidence13 Doing your bit14 How to apply the evidence to you and your situationPart VI: Testing your skill15 Making sense of health advice16 Is this a useful diagnostic test?17 Decision thresholds18 Relative risk, relative and absolute risk reduction, number needed to treat and confidence intervalsUseful sources of health adviceGlossaryAfter you read this bookIndex

About the authors

Les Irwig MB BCH, PhD is an internationally renowned expert on evidence-based medicine. Professor of Epidemiology at the University of Sydney, he has published widely in international medical journals. He is frequently invited to review evidence for the development of clinical guidelines and to serve on committees developing health policies. Professor Irwig has developed programmes to teach medical students and medical practitioners how to assess research and make health decisions. For this work, he received an Excellence in Teaching Award at the University of Sydney. He has also run courses to help journalists and the public understand how to interpret and use health information.

Judy Irwig has devoted a large part of her career to writing and recording songs for children, conveying important messages about relationships, self-respect and respect for the environment. She brings to this partnership the perspective of a healthcare consumer. Her non-medical background allows her to explain ideas clearly without resorting to technical jargon or making assumptions that often come from years of professional training

Lyndal Trevena MB BS(HONS), PhD is a general practitioner and a Senior Lecturer in the School of Public Health at the University of Sydney. She is interested in making evidence-based practice more feasible for busy clinicians and their patients, and ensuring that good quality information is at hand for making decisions with individual patients. Information about her research and other publications can be found at www.medfac.usyd.edu.au/people/academics/ profiles/lyndalt.php. Information about her practice can be found at www.asylumseekerscentre.org.au/. Decision aids and resources can be found at www.health.usyd.edu.au/shdg.

Melissa Sweet is an Australian writer and journalist, who has been reporting on health and medical issues for more than 15 years.

Before you read this book

We have designed this book to cover a range of health interests. It is easiest to read at the start and becomes more complex as it progresses. Depending on your needs and level of knowledge, you may choose the appropriate parts or chapters without necessarily reading from cover to cover.

Part I: Health advice can be harmful gives an introduction to the reasons why health advice may be misleading. It discusses some of the common pitfalls for consumers and health professionals, how to identify meaningful health claims and research, and why it can be unwise to rely on the opinions of the experts.

Part II: Your body, your choice is for you if you feel you have an understanding of the pitfalls in health advice, but need to know how to make better decisions by asking the right questions. It discusses the five key questions (see next page) to help make the best possible health decisions and what to look for when choosing a practitioner.

Parts III–VI are for you if you’re satisfied with your decision-making skills but need help in assessing whether your sources of information are reliable.

Part III: Stories and studies introduces the concepts of what features combine to make a good study.

Part IV: Evaluating the evidence deals with which study designs best answer questions such as whether a treatment works or what causes a disease.

Part V: Improving your healthcare explains where and how to find reliable evidence and how to use it, and suggests ways in which consumers can get involved in improving their health and healthcare services.

Part VI: Testing your skill starts with an opportunity to practise your skills on a range of articles from the media, internet and papers in the medical literature. Later chapters are for you if you want a more advanced understanding of numerical concepts underlying health decisions.

There is a glossary at the end of the book.

There are five questions that we suggest you ask when making a smart health choice. They form the core of this book and are covered in detail in Chapter 5. They are:

Acknowledgements

The idea for this book was conceived more than 15 years ago when Judy Irwig began to realise how fortunate she was to have an epidemiologist for a husband. When so many other people that she knew were floundering in a sea of often conflicting and confusing health information, Judy was able to ask Les to help her evaluate health advice. Often, Judy was surprised to discover that health information that was being widely circulated, whether in the media or by friends or even health professionals, was not reliable.

As Judy’s skills in appraising health advice developed, she began to think that everyone should have access to the same sort of information that she did. And so she started work on the themes of this book. Judy and Les then invited Melissa Sweet, a journalist who had written widely about evidence-based healthcare and the importance of patients playing an active role in their health decisions, to contribute to the project. The result was Smart Health Choices: How to make informed health decisions, published in Australia in 1999 by Allen & Unwin.

When it came time to update the book for this more international edition, Dr Lyndal Trevena, a Sydney GP and academic at the University of Sydney, was the perfect person for the job. Her commitment to evidence-based practice and 20 years’ experience as a GP gave her a powerful clinical and academic perspective on the issues so important for smart health choices. ‘I try to communicate with my patients about evidence whenever I can,’ says Lyndal.

This new edition contains many extra examples and sections. But Les is delighted that the core elements remain the same. ‘This suggests that the principles we recommend as important for making smart health choices will be of enduring help,’ he says.

The authors are delighted that the Australian cartoonist, Ron Tandberg’s work also features in the second edition.

The authors would also like to thank the many people who have contributed to this book, directly and indirectly. For their thoughtful comments and their encouragement along the way we thank:

Joan Austoker, Hilda Bastian, Kathy Bell, Wayne Bell, Helen and Ray Berman, Maria-Ines Bruce, Sidney Buckland, Carol Chaitowitz, Iain Chalmers, Barbara and Jonathan Craig, Vikki Entwistle, Trish Greenhalgh, David Grieve, Sonia Irwig, Wendy Fine, Steven Fine, Paul and Nancy Glasziou, Kevin Irwig, Marcelle and Ken Israelstam, Sue Jackson, Andre Joffe, Danielle Joffe, Lyn March, Gill Muncke, Gerd Muncke, Andy Oxman, Sally Redman, David Sackett, Martin Stockler, Fiona Stanley, Martin Tattersall.

Les and Judy would particularly like to thank their wonderful family for their love and support, and for believing so wholeheartedly in this project.

Lyndal would like to thank Steve, Daniel, Emma, Ruth, Janice and Don for their endless love and support.

We also thank those authors and researchers from whose books and studies we have taken examples.

Disclaimer

The decision-making techniques and advice presented in this book represent the opinions of the authors based on their training and experience, and are not intended to replace appropriate consultation with health practitioners. Many of the examples and studies cited may be out of date by the time that you read the book. They are intended to illustrate various principles rather than to be used as a basis for health decisions.

The authors and publishers expressly disclaim any responsibility for any liability, loss or risk, personal or otherwise, that is incurred as a consequence, directly or indirectly, of the use or application of any comments in this book.

The characters in the hypothetical examples and the short story are purely fictitious.

I

Health advice can be harmful

1

This book could save your life

In the past, information was the real bottleneck, so any improvement in information would lead to an improvement in thinking and in the quality of decisions. Information access and handling (by computers) have widened that bottleneck. So we move on to the next bottleneck. This is ‘thinking’. What do we do with the information?

Edward de Bono1

Every day we make decisions about our health – some big and some small, some conscious and some subconscious. What we eat, how we live and even where we live can affect our health. We make decisions about where to source information about maintaining good health, as well as about whom to see for treatment when we are ill.

We are bombarded with information about health on a daily basis. ‘Good health’ is highly valued and some people will go to great lengths to achieve it. Sometimes we worry whether we are making the right decisions and we seek assurances that we are receiving the best possible care. We often want answers to questions about a specific health condition. We might wonder about the meaning of certain test results, whether there are other treatment options and, if so, how effective they are. More and more people are also beginning to question whether tests and treatments might have side effects or involve risks.

Public confidence in traditional sources of health care has been understandably shaken in recent years by a number of high-profile hospital scandals and claims of negligence. In the UK, a major enquiry found three heart surgeons guilty of professional misconduct when 29 babies died between 1988 and 1995, more than double the rate in the rest of England.2 An enquiry into 29 deaths in Campbelltown and Camden Hospitals in New South Wales in Australia also found mismanagement, poor communication and under-resourcing.

Despite the intense publicity that usually surrounds such cases of medical negligence, these account for a relatively small proportion of the problems with people’s health care. A much broader problem arises from the care provided by well-meaning professionals in a system that is so fragmented and complicated that it is all too easy for things to go wrong. It is estimated that as many as 30,000 people die in the UK each year as a result of medical errors3 and that tens of thousands of Australians die or are seriously injured as a result of their healthcare. Seventeen per cent of hospital admissions are associated with an adverse event caused by healthcare management.4 In the USA, it has been estimated that about 180,000 people die each year partly as a result of their healthcare – the equivalent of three jumbo jet crashes every 2 days. These figures suggest that there is a great deal of room to improve the healthcare that many people receive.

Some people assume that complementary or ‘natural’ therapies provide a safer alternative to conventional options. However, there are many examples of people suffering side effects or complications from such therapies, whether from herbal products, acupuncture or chiropractic. In Australia in 2003 hundreds of vitamin and other products had to be recalled after 19 people were hospitalised and 87 reported feeling ill after taking a ‘natural’ travel sickness pill. Some alternative therapies can also interact with other medicines. Prince Charles sparked debate in May 2006 when he advocated greater access to complementary therapies at the World Health Assembly in Geneva and through the Smallwood report, which was commissioned by him. Some of Britain’s leading doctors followed with a letter to NHS trusts urging them to fund only therapies that were based on scientific evidence. They were particularly concerned about NHS funds being used for homeopathic treatments, given that research has not shown them to be effective and patients were not being told this.5 Early in 2007, a £200,000 pilot project of complementary therapies in Northern Ireland general practice had doctors complaining that the limited government health funds could be better spent on breast cancer drugs that have been shown to be effective in scientific studies.

This book will help you to evaluate the potential benefits and harms of various therapies, whether they are part of western medicine or a traditional or complementary practice. When making smart health choices, you should bear in mind what we don’t know as well as what we do know about the pros and cons associated with use.

Although many cases of harm result from human and/or system errors, there are many other ways in which harm can be done. Sometimes, bad things simply happen by chance and are unavoidable. In other cases, they are caused by the well-meaning, but ill-informed, use of treatments and tests that do more harm than good. In addition to this, there are tens of thousands of people who, although not being harmed by their care, are not receiving the best possible treatment for their situation. Studies in many countries have shown that the way the same condition is treated can vary dramatically, depending on where the patient lives or on which type of doctor or health practitioner they see. Much remains unknown about how best to prevent or treat many common conditions; however, there is widespread evidence that the information that is already available is often not put to best use.6

This situation has come about for many reasons. Historically, the medical and health professions have not placed sufficient emphasis on the proper evaluation of health practices, although evidence-based practice has become much more common in recent times. Commercial interests, such as pharmaceutical and medical technology companies, often drive the introduction of new practices before their harms and benefits have been carefully investigated. (More about that through the rofecoxib arthritis drug story later.) The media often disseminate misleading and even dangerous health information. And consumers themselves often seek out and recommend the use of ineffective and even harmful remedies, perhaps encouraged by misleading advertising, websites or the advice of well-intentioned friends and family.

This book aims to help consumers and practitioners develop the skills to assess health advice – and hopefully to make decisions that will improve the quality of their care. For some people, making better-informed decisions could be life saving. We hope that it will be useful if you are struggling to come to terms with an illness or injury, and the best ways of managing it. Or you may simply want to lead a healthier life, and may be wondering how to make sense of the often conflicting flood of health information that deluges us every day, through the media, and from our friends and health practitioners.

Medicine has a long history of introducing new treatments and other interventions before they have been properly evaluated and proved beneficial. In the late 1950s, American surgeons began introducing a new treatment for people with stomach ulcers that involved freezing the stomach. The first few patients so treated showed a dramatic improvement in ulcer symptoms, and the technique was enthusiastically adopted and used on tens of thousands of ulcer patients. When a proper evaluation was finally conducted, it found that subsequent surgery for ulcers, bleeding from the stomach or hospitalisation for severe pain occurred in 51 per cent of the patients randomly allocated to stomach freezing – compared with 44 per cent of patients randomly allocated to a sham treatment (placebo). (The quality of research is increased by random allocation of patients – for example, by the flip of a coin – to either an active treatment or a placebo treatment, or a comparative treatment.) Needless to say, the stomach freezing procedure was rapidly abandoned, but only after tens of thousands of people with ulcers received the wrong treatment because of insufficient evidence.

Sometimes, the widespread introduction of unproven treatments has had disastrous consequences. In the 1980s, a new treatment for a heart disorder is estimated to have killed tens of thousands of people. This disaster, described by Thomas Moore in his book Deadly Medicine,7 might have been prevented if the drug, flecainide, had been properly evaluated before its widespread use to control irregular heartbeats after a heart attack. It might have been prevented if more practitioners and consumers had been prepared to ask ‘What is the evidence to support the use of this new drug?’ The drug was approved for marketing after its manufacturer showed that it stopped several kinds of irregular heartbeats. However, it was introduced before studies had investigated whether this meant that it would also prevent deaths. When this research was finally done, it showed that the treatment had the opposite effect to that expected: it caused deaths.8

Unfortunately there are more recent examples of widely used treatments proving to be harmful after more rigorous evaluation has been conducted. Two examples that we will consider in more detail later in this book are the withdrawal of rofecoxib, an anti-inflammatory medicine used for arthritis, which was found to increase the risk of heart attacks and strokes, and the change in use of hormone replacement therapy after the results of a large randomised trial called the Women’s Health Initiative (WHI).

This book is in no way intended as a do-it-yourself guide to becoming your own doctor. It is hoped, however, that it will help you to assess health advice better by showing you how to recognise useful evidence and reject that which is likely to be harmful. Its underlying argument – that we should remain cautious about any intervention that has not been thoroughly investigated and proved to do more good than harm – applies to all health advice, whether it comes from mainstream medicine or complementary/alternative practitioners.

The book is based on the philosophy that consumers have a right to develop a health partnership with their practitioner, so that all decisions take account of their personal preferences, as well as being based on accurate information about the beneficial and harmful effects of interventions. We hope that it will enlighten and empower those who may be feeling disgruntled with their healthcare, or who are confused by all the conflicting opinions and information that they are given, or who feel that their practitioners are not taking their viewpoints into account. The book will also be useful to readers making health decisions on their own, without consulting a practitioner.

We believe that the information in this book could have a profound impact on your health by offering simple tools to distinguish between good advice and potentially harmful advice. This knowledge could mean the difference between choosing the most effective treatment or choosing one that may be useless or even life threatening. Perhaps this book will save your life – or that of someone close to you.

References

1. de Bono E. Parallel Thinking. London: Penguin, 1994.

2. The Bristol Royal Infirmary Inquiry, 2001: http://webarchive.nationalarchives.gov.uk/ +/www.dh.gov.uk/en/Publicationsandstatistics/Publications/ PublicationsPolicyAndGuidance/DH_4005620

3. Weingart SN, Wilson RMcL, Gibberd RW, Harrison B. Epidemiology of medical error. BMJ 2000;320: 774–777.

4. Wilson R, Runciman W, Gibberd R, Harrison B, Newby L, Hamilton J. The quality in Australian Health Care Study. Med J Australia 1995;163:458–71.

5. BBC News. Doctors attack ‘bogus’ therapies, 23 May 2006: http://news.bbc.co.uk/2/hi/5007118.stm

6. Antman M, Lau J, Kupelnick B, Mosteller F, Chalmers T. A comparison of results of meta-analyses of randomised trials and recommendations of clinical experts. JAMA 1992;268:240–8.

7. Moore T. Deadly Medicine: Why tens of thousands of patients died in America’s Worst drug disaster. New York: Simon & Shuster, 1995.

8. CAST (Cardiac Arrhythmia Suppression Trial (CAST) Investigators). Preliminary report: Effect of encainide and flecainide on mortality in a randomized trial of arrhythmia suppression after myocardial infarction. N Engl J Med 1989;321:406–12.

2

Be sceptical

What has not been examined impartially has not been well examined. Scepticism is therefore the first step towards truth.

Denis Diderot, Pensées Philosophiques

This chapter forms the basis of making ‘smart health choices’ because it encourages you to ask questions about the health advice that you receive – whether it comes from a television advertisement, a friend or a health professional. It will give you some of the tools to be sceptical, a critical thinker who can sift the misleading advice from that which has a genuine basis.

First, it is important to understand how our own biases can influence us. It is human nature to be tempted to believe explanations because they sound plausible, or because they agree with a prior belief or fit in with our value systems. Similarly, it can be difficult to give up a long-standing belief, even if not supported by the available evidence.

An example of this comes from the history of the tomato, which originated from South America and became a popular food in Europe by the mid-1500s. However, North Americans did not cultivate it until the twentieth century. They believed it to be poisonous, because it belongs to the Nightshade family, which includes some poisonous plants. The fact that Europeans had been eating tomatoes safely for centuries did not change their view.1

There are many examples of people’s health suffering because of practitioners’ failure to change their thinking in response to new medical evidence. It has been estimated, for example, that tens of thousands of premature babies around the world died or suffered health problems that could have been prevented had doctors been quicker to act on research evidence showing the benefits of giving corticosteroid drugs to expectant mothers going into premature labour.

On the other hand, new tests and treatments can be adopted too quickly, sometimes as a result of commercial pressure and sometimes for political reasons.

It is important to be critical of your own decision-making processes. Are you choosing or avoiding a particular treatment simply because that is what you or your family have always done, without investigating its harms and benefits or whether it is your best option? Be aware that healthcare practitioners also have their own personal and professional biases; a chiropractor will take a different approach to back pain to a surgeon, whereas cardiologists may have different views from liver specialists about the health impact of alcohol.

But perhaps you should reserve your most sceptical thinking for what you read or hear in the media. Consider a news report that cites a professor saying that the latest research suggests that drug x is a breakthrough new treatment for high blood pressure. If the professor’s views are being disseminated as part of a campaign by the drug’s manufacturer, this is unlikely to be mentioned in the news story. Similarly, if you read a report where an expert is sounding the alarm about the safety of a certain drug, it may well be that the expert’s views are being disseminated as part of a campaign funded by the manufacturer of an opposition drug. Again that will not necessarily be mentioned in the news story. Such stories often do not put the experts’ claims into a broader context – for example, looking at how they compare with other research in the area. And they rarely look critically at what evidence might be available to support the experts’ claims. Clearly, it would not be wise to take such stories at face value.

However, many consumers and even health professionals rely on the news media for information about health. The problem with this is that ‘news’, by its very definition, is that which is unusual, sensational, scandalous or stirring. The media’s preoccupation with rare, sensational events tends to make us lose perspective of what is normal. News is also susceptible to distortion and misinterpretation. The media are more likely to report studies with a ‘positive’ finding, such as those linking power lines to childhood cancer. ‘Negative’ studies – those finding no link – are much less likely to be reported. It is unusual for the complexities of health information to be accurately or fully conveyed in the media.

The media may report a new ‘breakthrough’ study showing that one treatment increased the survival of people with cancer by 10 per cent. It may not mention, however, that what this actually meant was that, one year after treatment, 110 of 1000 patients were alive instead of the 100 of 1000 who would have survived without treatment. Furthermore, it may not mention that what this meant for longer-term survival was unclear, and that the usefulness of the treatment was still uncertain because of its side effects.

Media coverage of health-related news can have significant effects on people’s health behaviour. After Kylie Minogue’s diagnosis of breast cancer there was a 20-fold increase in average daily television time given to breast cancer over a 2-week period. Messages during this time emphasised that breast cancer can ‘strike at any age’. Although to some extent this is true, this message fails to point out that, while breast cancer does occur in women under the age of 40, it is much less common than in older women. Accompanying media messages at this time were critical of the government for not extending free mammograms to women of all ages. However, they neglected to explain that mammography is not a very accurate test in the breasts of younger women who have not yet reached the menopause. They also neglected to mention that mammography, as with most tests, is not entirely without risks. After this publicity the number of women booking mammograms went up by 40 per cent. But the increase was much higher in women aged 40–49 years compared with older women aged 50–69 years (25 per cent increase).2 In other words, the intense media focus on Kylie Minogue’s breast cancer seems to have made some younger women overly anxious about their risk of the disease.

Most journalists and media managers are not qualified to assess scientific data and to discriminate between high-quality studies and the many studies that are of poor quality and dubious value. You can be more confident of the validity of a study if it is reported as being published in a well-known medical or scientific journal, but this is no guarantee. Reports of such single studies often fail to include the broader context, so that the results are reported as if conclusive fact, whereas they may be tentative and not in line with other valid studies.

And most journalists and media managers are looking for a ‘story’; the stronger and more exciting they can make the findings sound, the more chance that their story will be displayed prominently. One journalist expresses it this way:

Scientists who do poor studies or overstate their results deserve part of the blame. But bad science is no excuse for bad journalism. We tend to rely most on ‘authorities’ who are either most quotable or quickly available or both, and they often tend to be those who get most carried away with their sketchy and unconfirmed but ‘exciting’ data – or have big axes to grind, however lofty their motives. The cautious, unbiased scientist who says, ‘Our results are inconclusive’ or ‘We don’t have enough data yet to make any strong statement’ or ‘I don’t know’ tends to be omitted or buried someplace down in the story.

Victor Cohn3

Advertisements also have a powerful impact on our healthcare, whether by influencing a doctor’s decision about what drug to prescribe or by persuading you to buy a particular food or pill. Tips for avoiding the tricks and traps of advertising can also be useful for evaluating other forms of health advice.

And, of course, there’s the internet! An ever-increasing amount of health information is now available to everyone online. More and more, people are turning to the internet to look up health information, to try to find out more about either their own health problem or the health of a family member, perhaps to double-check information that they’ve received from a health practitioner or to ‘chat’ with people who have the same health problem via discussion groups and ‘blogs’. Health programs can be downloaded via podcasts and played through i-pods while walking the dog.

Below are some of the common strategies used in selling health messages, why they can lead you astray and how to evaluate them.

If it works on a rat, it will work on you

Many reports claim that a certain product has been scientifically proven to have various benefits. But the fine print reveals that the results come from laboratory or animal experiments. It cannot be assumed that these results will be relevant for humans. Different species respond differently to various treatments.

For years many scientists were convinced that taking supplements of the antioxidant, beta-carotene, related to vitamin A, would reduce the risk of certain cancers and heart disease. One of the reasons for their optimism was that animal studies had suggested that vitamin A was protective against cancer in some situations. The theory was strengthened by observational studies showing that people with higher blood levels of beta-carotene had lower rates of cancer and heart disease. But when proper trials were done – randomly allocating individuals to beta-carotene or placebo supplements (dummy pills) – the results surprised many. An analysis of 47, well-conducted, randomised controlled trials showed that antioxidant supplements (beta-carotene, vitamins A, C and E, and selenium) do not reduce your chance of dying. In fact taking betacarotene or vitamin A or E appeared to increase it.4 To add further weight to this, another summary of the effect of beta-carotene on preventing cancers of the bowel, liver, stomach and pancreas also showed that it increased your chance of dying! It seems that, in humans, taking beta-carotene, vitamin A and vitamin E (alone or in combination) may do you more harm than good.5–7

Tip

You need to know the evidence proving that the product works on humans – and that its effect is relevant to your needs and situation.

Here’s how it works

A remedy which is known to work, though nobody knows why, is preferable to a remedy which has the support of theory without the confirmation of practice…. The question to which we must always find an answer is not ‘should it work?’ but ‘does it work?

Richard Asher8

People selling health messages, especially advertisers, love to tell you ‘how their product works’. This strategy can be very convincing because it seems to make ‘good sense’ that, if we understand the mechanism by which something might work, the hoped-for outcome will automatically follow. But knowing how something is supposed to work is not proof that it does work.

For example, knowing that a substance changes the lining of your stomach, or plumps out your skin cells – these are examples of markers which are sometimes called surrogate or intermediate measures – may be intriguing, but is certainly no proof that you will have better digestion or smoother skin. These outcomes that matter to you are often called ‘person-centred outcomes’. And on a more serious note, remember the story of flecainide, the drug that was meant to reduce deaths by treating irregular heart rhythms, but in fact increased the risk of death. What we really need to know is whether a product or treatment will improve our quality of life or help us to live longer.

Similarly, we should not discard treatments that have been proven to have benefits, simply because we do not understand how they work. Many thousands of women and their babies probably suffered unnecessarily because the medical profession was reluctant to accept that the anticonvulsant, magnesium sulphate, was an effective treatment for eclampsia because they did not see how it could possibly work. Eclampsia causes swollen feet, high blood pressure and fits in pregnant women, and accounts for about 10 per cent of all maternal deaths worldwide – about 50,000 deaths a year. A summary of the results of six randomised trials has shown that magnesium more than halves the risk of eclampsia and was better than other anticonvulsants, although there is a small increased risk of caesarean section (5 per cent).9

People who dismiss alternative health therapies because their mechanisms ‘do not make sense’ may be as misguided as those who believe a therapy will work because its mechanism suggests it ought to.

Tip

You need to know whether an intervention works in practice (empirical evidence). This can come only from seeing what actually happens to people who have the intervention. We get this information from good quality trials on people rather than from theory alone. Person-centred outcomes describe how an intervention affects your quality or length of life.

Blind you with science

Product promotions aimed at the general public and at doctors are notorious for using inconclusive or misleading research, wrapped up in scientific jargon, in an attempt to inspire support for a product.

And even if valid research is cited, you cannot assume that it will be quoted accurately or fairly. Consider this advertisement aimed at medical practitioners for a cholesterol-lowering drug called Zocor or simvastatin. In 1993 the pharmaceutical company brochure included this quote from a 1991 independent medical report:

HMG-CoA reductase inhibitors such as simvastatin … are the most effective in lowering cholesterol levels and are more acceptable to patients than the bile acid resins….