How to Read a Paper

"One of the greatest aspects of this book is the section relating to searching the literature and whilst we may think we may all practise this on a fairly regular basis under the assumption that we do a pretty decent job of it, this section holds the key to excelling." (Urology News, May/June 2009)

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 xii Preface to the sixth edition xiv Preface to the first edition xvi Acknowledgements xviii Chapter 1 Why read papers at all? 1 Does evidencebased medicine simply mean reading papers in medical journals? 1 Why do people sometimes groan when you mention evidencebased 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 Preappraised sources: synopses of systematic reviews and primary studies 22 Specialised resources 23 Primary studies tackling the jungle 23 Onestop 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 Casecontrol studies 40 Crosssectional 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 nonstatistician 62 How can nonstatisticians 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 metaanalyses) 117 When is a review systematic? 117 Evaluating systematic reviews 120 Metaanalysis for the nonstatistician 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 Pape