Evidence into Practice: how to read a paper

Rob Sneyd(with help from...Andrew F. Smith, Lancaster, UK)

Outline

• Evidence-based medicine• Appraisal of published trials• The anatomy of a journal

Four steps to evidence-based practice

1. Ask a clinical question2. Search for evidence3. Critically appraise the evidence4. Integrate the evidence into practice

Levels of evidence

I Systematic review of RCT’sII Single RCTIII Cohort studiesIVCase seriesV Single case report

Appraisal of published studies

‘Is this paper any good?’

1. Validity2. Applicability3. Logical flow

Validity: bias and distortion

Bias in clinical trials

• Recruitment• Selection• Allocation • Performance• Observer• Inference• Reviewer

Bias in clinical trials

• Recruitment• Selection• Allocation Randomisation• Performance Blinding• Observer Blinding• Inference• Reviewer

Introduction

Method

Introduction

Method

• Meaningful outcomes• Inclusion and exclusion• Detail - replicability• Measurement tools• Allocation concealment• Blinding and control groups• Follow-up and dropouts• Power calculation and significance

Method

Results

Introduction

Method

Discussion

Results

Introduction

Discussion

• Summary of main findings• Comment on strengths and weaknesses• Comparison with other studies – similarities

and differences• Mechanisms and implications• Unanswered questions and future work

Method

Conclusion

Discussion

Results

Introduction

Method

Conclusion

Discussion

ResultsAbstract

Introduction

Anatomy of the anaesthesia journal

Editorials

• ‘Rarely contain primary data’• Help interpret research and promote its use in

practice• Promote discussion • Offer ‘authoritative’ opinion

What are review articles for?

• Answering clinical questions• Keeping up to date• Starting-point for future research• Assimilating primary research

Systematic review

‘A review in which evidence on a topic has been systematically identified, appraised and summarised according to predetermined criteria’

Systematic review

1. Decide scope and purpose2. Exhaustive search for material3. Inclusion on pre-defined criteria4. Quality assessment of relevant studies5. Data extraction6. Synthesis and integration7. Interpretation

Case reports

• Focus on individuals rather than populations• Narrative power• Archive of collective experience• Sensitive to novelty: new benefits,

complications, the unknown and unrecognised

Correspondence

• ‘The proper dialogue of science’• Extend journals’ peer review by readers’

comments, corrections and interpretation• Not usually peer reviewed• Under-rated and poorly indexed

Conclusion

• Simple non-statistical principles can help make sense of research

• Evidence and opinion both have their place but should not be confused

• Bias is everywhere and must be taken into account

• Critical appraisal helps us identify good evidence