How to Read a Paper

TRISHA GREENHALGH, OBE, FMedSci is Professor of Primary Care Health Sciences, Nuffield Department of Primary Care Health Sciences, Medical Sciences Division, University of Oxford, UK.

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