EVIDENCE BASED MEDICINE, ‘PLACEBOS’ AND THE HOMEOPATHY CONTROVERSY ANDREW JAMES TURNER, BA. MA. Thesis submitted to the University of Nottingham for the degree of Doctor of Philosophy JULY 2012 1 2 ABSTRACT Homeopathic treatment has been available on the UK’s National Health Service (NHS) since 1948. In recent years the continued provision of homeopathy through the NHS has been increasingly questioned as part of the ascendency of evidence-based medicine (EBM). Indeed, in 2009 the House of Common’s Science and Technology committee commenced an ‘Evidence Check’ inquiry into Government policy supporting the NHS provision of homeopathic treatments. The controversy over whether homeopathic treatments ‘really’ work and whether they should be available through the NHS has generated much debate: at the heart of the controversy are questions about the nature of evidence in medicine, the validity of randomised trials and the nature and utility of ‘placebo effects’. Critics of homeopathy put forward the simple argument that best available evidence shows homeopathic treatments to be equivalent to placebo, and therefore conclude that it should not be available through publically funded healthcare. This thesis presents a critical examination of the concepts of EBM and ‘placebos’ and re-evaluates their role in the controversy around homeopathy. This thesis examines what kind of foundation the EBM philosophy of evidence provides for the arguments made in the controversy, and the role that ‘placebos’ play as both an evidential and normative standard. There are two basic arguments: first, that the arguments justifying the EBM philosophy of evidence are fundamentally unclear, but also that the interpretation given to EBM, in debates about homeopathy, cannot be sustained. Second, that the concept of ‘placebos’ should be abandoned entirely: a framework is developed for talking about the effectiveness of treatments that removes much confusion about the epistemological and ethical standards that effective treatments should be held to. In addition to attempting to provide conceptual clarity to the controversy, the main conclusion is that the Science and Technology Committee have (on the basis of their own assumptions) understated their evidential arguments, by ignoring mechanistic evidence for whether homeopathic treatments are effective, and they have overstated their ethical arguments, they do not provide good reasons to remove provision of homeopathic treatment through the NHS. 3 ACKNOWLEDGEMENTS The most thanks to my supervisors, Prof. Paul Martin and Prof. Cees van der Eijk for their ideas, guidance and support. Many thanks also to the Foundation for the Sociology of Health & Illness, for the studentship which has funded this PhD. Thanks too, to everyone within the Institute for Science & Society, which has been a truly fantastic place to work. And thanks to Rachel Johnson, the source of many of the medical examples. Note An early version of Chapter 10 has been published as: Turner, A (2012) ‘Placebos’ and the Logic of Placebo Comparison, Biology & Philosophy, 27(3), 419- 432. doi:10.1007/s10539-011-9289-8. 4 CONTENTS PART ONE: THE HOMEOPATHY CONTROVERSY ............................................ 7 CHAPTER 1............................................................................................................ 8 1. INTRODUCTION ....................................................................................................... 8 CHAPTER 2.......................................................................................................... 11 2. WHAT IS HOMEOPATHY? ......................................................................................... 11 2.1 HISTORICAL INTRODUCTION AND KEY PRINCIPLES ..................................................... 11 2.2 THE CONTROVERSY ............................................................................................. 20 2.3 SUMMARY ........................................................................................................ 29 CHAPTER 3.......................................................................................................... 30 3. WHAT ARGUMENTS ARE PUT FORWARD IN THE CONTEMPORARY CONTROVERSY? ............. 30 3.1 THE EVIDENTIAL DEBATE ...................................................................................... 31 3.2 THE POLICY DEBATE ............................................................................................ 51 3.3 SUMMARY ........................................................................................................ 63 CHAPTER 4.......................................................................................................... 66 4. SUMMARY OF PART ONE AND THE QUESTIONS TO BE ADDRESSED IN THIS THESIS .............. 66 4.1 INTRODUCTION TO PART TWO ............................................................................. 67 PART TWO: EVIDENCE BASED MEDICINE.................................................... 69 CHAPTER 5.......................................................................................................... 70 5. WHAT IS EVIDENCE-BASED MEDICINE? ..................................................................... 70 5.1 ORIGINS AND DEFINITION .................................................................................... 70 5.2 THE BASIC ARGUMENTS FOR EVIDENCE-BASED MEDICINE .......................................... 75 5.3 PROBLEMS INTERPRETING EVIDENCE-BASED MEDICINE ............................................. 81 5.4 SUMMARY ........................................................................................................ 90 CHAPTER 6 ......................................................................................................... 92 6. IS THERE A CLEAR ACCOUNT OF EVIDENCE-BASED MEDICINE IN THE MEDICAL LITERATURE? . 92 6.1 METHOD .......................................................................................................... 93 6.2 RESULTS ......................................................................................................... 106 6.3 DISCUSSION .................................................................................................... 128 6.4 SUMMARY ...................................................................................................... 134 CHAPTER 7........................................................................................................ 136 7. HOW SHOULD EVIDENCE-BASED MEDICINE BE INTERPRETED? ...................................... 136 7.1 IS THE CATEGORICAL INTERPRETATION DEFENSIBLE? ............................................... 137 7.2 SOLUTIONS TO THE PROBLEMS ........................................................................... 141 7.3 RE-INTERPRETING EVIDENCE-BASED MEDICINE ...................................................... 146 7.4 SUMMARY ...................................................................................................... 155 5 CHAPTER 8 ........................................................................................................ 157 8. SUMMARY OF PART TWO ...................................................................................... 157 8.1 INTRODUCTION TO PART THREE .......................................................................... 158 PART THREE: PLACEBOS .......................................................................... 160 CHAPTER 9 ........................................................................................................ 161 9. PLACEBOS AND THE HOMEOPATHY CONTROVERSY ...................................................... 161 9.1 PLACEBOS AND PLACEBO EFFECTS ........................................................................ 163 9.2 WHICH COMPONENTS OF A TREATMENT CAN CAUSE PLACEBO EFFECTS? .................... 173 9.3 MEANING-THEORIES OF PLACEBO EFFECTS ............................................................ 181 9.4 SUMMARY ...................................................................................................... 183 CHAPTER 10 ...................................................................................................... 185 10. PLACEBOS AND THE LOGIC OF PLACEBO COMPARISON ............................................. 185 10.1 PLACEBO COMPARISON ..................................................................................... 186 10.2 PLACEBO COMPARISON WITHOUT ‘PLACEBOS’ ....................................................... 194 10.3 SUMMARY ...................................................................................................... 200 CHAPTER 11 ...................................................................................................... 201 11. IMPLICATIONS OF THE ARGUMENTS ABOUT ‘PLACEBOS’ ........................................... 201 11.1 EFFICACY AND EFFECTIVENESS ............................................................................ 202 11.2 THE ETHICAL SIGNIFICANCE OF PLACEBO COMPARISON ............................................ 212 11.3 SUMMARY ...................................................................................................... 224 CHAPTER 12 ...................................................................................................... 226 12. SUMMARY OF PART THREE ................................................................................ 226 12.1 INTRODUCTION TO PART FOUR ........................................................................... 227 PART FOUR: RE-EVALUATING THE CONTROVERSY ....................................