How to Read a Paper

Foreword to the first edition by Professor Sir David Weatherall xii Preface to the sixth edition xiv Preface to the first edition xvi Acknowledgements xviii Chapter 1 Why read papers at all? 1 Does ‘evidence‐based medicine’ simply mean ‘reading papers in medical journals’? 1 Why do people sometimes groan when you mention evidence‐based healthcare? 4 Before you start: formulate the problem 11 Exercises based on this chapter 13 References 14 Chapter 2 Searching the literature 16 What are you looking for? 17 Levels upon levels of evidence 18 Synthesised sources: systems, summaries and syntheses 19 Pre‐appraised sources: synopses of systematic reviews and primary studies 22 Specialised resources 23 Primary studies – tackling the jungle 23 One‐stop shopping: federated search engines 25 Asking for help and asking around 26 Online tutorials for effective searching 26 Exercises based on this chapter 27 References 27 Chapter 3 Getting your bearings: what is this paper about? 29 The science of ‘trashing’ papers 29 Three preliminary questions to get your bearings 31 Randomised controlled trials 35 Cohort studies 38 Case–control studies 40 Cross‐sectional surveys 41 Case reports 41 The traditional hierarchy of evidence 42 Exercises based on this chapter 43 References 43 Chapter 4 Assessing methodological quality 45 Was the study original? 45 Whom is the study about? 46 Was the design of the study sensible? 47 Was bias avoided or minimised? 49 Was assessment ‘blind’? 53 Were preliminary statistical questions addressed? 54 A note on ethical considerations 57 Summing up 58 Exercises based on this chapter 59 References 60 Chapter 5 Statistics for the non‐statistician 62 How can non‐statisticians evaluate statistical tests? 62 Have the authors set the scene correctly? 64 Paired data, tails and outliers 69 Correlation, regression and causation 71 Probability and confidence 73 The bottom line 75 Summary 77 Exercises based on this chapter 77 References 78 Chapter 6 Papers that report trials of drug treatments and other simple interventions 79 ‘Evidence’ and marketing 79 Making decisions about therapy 82 Surrogate endpoints 82 What information to expect in a paper describing a randomised controlled trial: the CONSORT statement 86 Getting worthwhile evidence from pharmaceutical representatives 86 Exercises based on this chapter 89 References 89 Chapter 7 Papers that report trials of complex interventions 92 Complex interventions 92 Ten questions to ask about a paper describing a complex intervention 94 Exercises based on this chapter 99 References 100 Chapter 8 Papers that report diagnostic or screening tests 101 Ten men in the dock 101 Validating diagnostic tests against a gold standard 102 Ten questions to ask about a paper that claims to validate a diagnostic or screening test 107 Likelihood ratios 111 Clinical prediction rules 113 Exercises based on this chapter 114 References 115 Chapter 9 Papers that summarise other papers (systematic reviews and meta‐analyses) 117 When is a review systematic? 117 Evaluating systematic reviews 120 Meta‐analysis for the non‐statistician 125 Explaining heterogeneity 130 New approaches to systematic review 132 Exercises based on this chapter 133 References 133 Chapter 10 Papers that tell you what to do (guidelines) 137 The great guidelines debate 137 Ten questions to ask about a clinical guideline 141 Exercises based on this chapter 147 References 148 Chapter 11 Papers that tell you what things cost (economic analyses) 150 What is economic analysis? 150 Measuring the costs and benefits of health interventions 152 A note on ‘Choosing Wisely’ 157 Ten questions to ask about an economic analysis 157 Conclusions 162 Exercises based on this chapter 162 References 162 Chapter 12 Papers that go beyond numbers (qualitative research) 165 What is qualitative research? 165 Ten questions to ask about a qualitative research paper 169 Conclusions 176 Exercises based on this chapter 176 References 177 Chapter 13 Papers that report questionnaire research 179 The rise and rise of questionnaire research 179 Ten questions to ask about a paper describing a questionnaire study 180 Conclusions 188 Exercises based on this chapter 189 References 189 Chapter 14 Papers that report quality improvement case studies 191 What are quality improvement studies, and how should we research them? 191 Ten questions to ask about a paper describing a quality improvement initiative 193 Conclusions 200 Exercises based on this chapter 200 References 201 Chapter 15 Papers that describe genetic association studies 203 The three eras of human genetic studies (so far) 203 What is a genome‐wide association study (GWAS)? 204 Clinical applications of GWAS 207 Direct‐to‐consumer genetic testing 209 Mendelian randomisation studies 210 Epigenetics – a space to watch 211 Ten questions to ask about a genetic association study 212 Conclusions 216 Exercises based on this chapter 216 References 216 Chapter 16 Applying evidence with patients 219 The patient perspective 219 Patient‐reported outcome measures (PROMs) 221 Shared decision‐making 222 Option grids 223 N of 1 trials and other individualised approaches 227 Exercises based on this chapter 228 References 229 Chapter 17 Criticisms of evidence‐based healthcare 232 What’s wrong with EBHC when it’s done badly? 232 What’s wrong with EBHC when it’s done well? 235 Why is ‘evidence‐based policymaking’ so hard to achieve? 238 Exercises based on this chapter 239 References 240 Appendix 1 Checklists for finding, appraising and implementing evidence 242 Appendix 2 Assessing the effects of an intervention 252 Index 253