JLL Book of Essays, About Fair Tests, May 2019
At various times in our lives and to varying levels of intensity, we all use, provide or pay for health and social care. As we decide what to do, take, offer or buy, we need evidence that is reliable, robust and trustworthy about different options. Even before James Lind’s experiment comparing possible treatments for scurvy on HMS Salisbury people had recognised that getting this evidence requires strenuous efforts to reduce bias –but that achieving this is often not straightforward. This book of essays from the James Lind Library is our attempt to illustrate some of the challenges encountered and how to overcome them.
We will take you on a journey through the sometimes stormy waters of why treatments need to be tested, rather than being based on assumptions that “it must work” before the treatment has even been tried, or based on impressions after it has been used a few times, through to the need for fair tests comparing alternative treatment options. We will show why genuine uncertainties must be identified and addressed, and how research to find the most effective and appropriate treatments need to build on research to identify the most effective and appropriate methods for doing that research. We will navigate through the reasons why comparisons need to be fair at the outset, and then kept fair as the treatments being tested are given;outcomes are measured;and results are analysed, reported, and combined in systematic reviews of all the relevant, trustworthy evidence.
We have not cluttered the chapters with references to all the source material on which we have drawn. For that level of detail, please follow the links to the fuller essays on the James Lind Library website. Instead, where we know of reviews of methodology research which are relevant to a topic, we have listed these at the end of each chapter.
By the end of the book, we hope that you will recognise how, to bring benefits of research to patients and the public, systematic reviews of fair tests are needed to provide key elements of the knowledge needed to inform decisions about health and social care, while taking into account other important factors, such as values, preferences, needs, resources and priorities. We also hope that, as you finish the book, you will share the sense of enlightenment, education and enjoyment that we have gained from preparing it.
Finally, we dedicate this book to England’s National Institute for Health Research. Without the Institute’s 16-year-long support for the James Lind Initiative, the home of the James Lind Library during that time, neither the Library nor these essays would have been possible. And we also wish to acknowledge the role the Institute plays in recognising the vital contribution of research to the delivery of health and social care that is effective and efficient, and the Institute’s leadership in ensuring that the research itself is effective, efficient and reliable, with minimal waste.
1.3 Why treatment comparisons must be fair
Untrustworthy treatment comparisons are those in which biases, or the play of chance, or both result in misleading estimates of the effects of treatments. Fair treatment comparisons avoid biases and reduce the effects of the play of chance.
It is not only failure to test theories about treatments in practice that has caused preventable tragedies. They have also occurred because the tests used to assess the effects of treatments have been unreliable and misleading. In the 1950s, theory and poorly controlled tests yielded unreliable evidence suggesting that diethylstilboestrol (DES) helped pregnant women who had previously had miscarriages and stillbirths. Although fair tests suggested that DES was useless, theory and unreliable evidence, together with aggressive marketing, led to DES being prescribed to millions of pregnant women over the next few decades. The consequences were disastrous for the women and their children, who experienced infertility and cancers as a result. The lesson is that a treatment that has not been reliably shown to be useful should not be promoted.
Problems resulting from inadequate tests of treatments continue to occur. Again, because of unreliable evidence and aggressive marketing, millions of women were persuaded to use hormone replacement therapy (HRT). It was claimed that, not only could it reduce unpleasant menopausal symptoms, but also the chances of having heart attacks and strokes. When these claims were assessed in fair tests, the results showed that in women over 60, far from reducing the risks of heart attacks and strokes, HRT increases the risks of these life-threatening conditions, as well as having other undesirable effects.These examples of the need for fair tests of treatments are a few of many that illustrate how treatments can do more harm than good. Improved general knowledge about fair tests of treatments is needed so that –laced with a healthy dose of scepticism –we can all assess claims about the effects of treatments more critically. That way, we will all become more able to judge which treatments are likely to do more good than harm.
DES DiEthylStilbestrol Resources