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Critical Appraisal of a RCT

Critical Appraisal of a RCT. Dr Donncha O’Gradaigh, EBP Group South East. assess. appraise. ask. acquire. apply. Fair tests. Testing Treatments link. Clinical scenario….

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Critical Appraisal of a RCT

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  1. Critical Appraisal of a RCT Dr Donncha O’Gradaigh, EBP Group South East

  2. assess appraise ask acquire apply

  3. Fair tests Testing Treatments link

  4. Clinical scenario… • After a sports event, two of your team-mates are debating whether there is any benefit from anti-inflammatory gel for an ankle sprain

  5. Validityreliability significance

  6. PICO - matching Patient / Population Will the results be relevant to your patient? Is your patient in a sub-group? Intervention Control / comparison Is the comparison relevant and fair (placebo versus active comparators) Outcome Clinically relevant? Patient preference?

  7. Some definitions www.students4bestevidence.net offer glossary of terms

  8. The METHODS section

  9. Systematic approaches to appraisal of “reliability” in study design RAMMbo and GATES

  10. RAMMbo Recruitment representative sample – age, symptoms… • of the population? • of the way you will meet the next one (random, consecutive, exclusions)?

  11. RAMMbo • Allocation • Equal chance of either intervention or control • Stratification in randomisation • Computer versus envelopes • “Blind” generally refers only to allocation – no use if subsequent process reveals allocation • “Double dummy”, marks, adverse effects; acupuncture studies

  12. RAMMbo • Maintenance in the study • Protocol violations versus allowed • Consider all the possible differences Maintain blinding • Record drop-outs • 80:20 guide

  13. RAMMbo • Measurement (of outcome) • Is the measurement appropriate for the treatment • Is the measurement appropriate for your patient’s clinical query • carried out without bias • Blinded (b) assessor or objective (o)tool (both?)

  14. R P A M I/C Mbo O

  15. the Results section-or “is this any use?”

  16. “I need a p”

  17. DESIGN Result = truth + bias + random error MEASURE

  18. Understanding bias and error

  19. the result is an ESTIMATE from a SAMPLE

  20. how do 95% CI and p relate? measured difference between the two arms If there was no difference between treatment arms 95% CI The range of values the difference might have

  21. Spot the [deliberate] error “Our results show a highly significant (p<0.001) effect of metwostatin on LDL cholesterol” “our study of 53 individual patients shows that there is no benefit from this intervention (p=0.051)” “While the effect of x-mab on pain did not reach significance (p>0.05), the significant reduction in radiographic progression (p=0.029) is an important benefit of treatment”

  22. In the workshop • A medication RCT • Methodolgy, RAMMbo • Results – two different types • Your own Clinical Query / group project • A two step intervention • More complex, maybe more real-life • More technical aspects of trial design

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