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Analyzing Therapy in Medical Literature: Part 1

Learn how to analyze therapy in medical literature. This article covers topics such as randomized controlled trials, appraising RCTs using a checklist, and understanding concepts like randomization, blinding, and intention-to-treat analysis.

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Analyzing Therapy in Medical Literature: Part 1

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  1. How to Analyze Therapy in the Medical Literature(part 1) Akbar Soltani. MD.MSc Tehran University of Medical Sciences (TUMS) Shariati Hospital www.soltaniebm.com

  2. Objectives • What is randomized controlled trial? • How to appraise RCT using standard checklist • Review different concepts such as • Randomization, allocation concealment, blinding, loss to follow up, intention to treat analysis

  3. The hierarchy of evidence • Systematic reviews and meta-analyses • Randomised controlled trials • Cohort studies • Case-control studies • Cross sectional surveys • Case reports • Expert opinion

  4. Three Step Guide in Using an Article to Assess Therapy • Are the results of the study valid? • What are the results? What measures of precision of effects were reported (CIs, p-values)? • How can I apply these results to patient care?

  5. Randomized control trial design

  6. Assess Validity and Applicability to my practice setting 1.Is the study a randomized control trial (RCT)? Yes (go on) No (stop) 2.Were the patients properly selected for the trial and randomized with concealed assignment? Yes (go on) No (stop) 3.Were patients and study personnel “blind” to treatment? Yes (go on) No (pause) 4.Were the intervention and control groups similar at the start? (Check “Table 1” of most studies) Yes (go on) No (stop) 5.Was follow-up complete? ii. Were patients analyzed in the groups to which they were randomized (“intention-to-treat” analysis)?

  7. Benefits of Random Allocation (Randomization) 1.Reduces bias in those selected for treatment • guarantees treatment assignment will not be based on patients’ prognosis 2.Prevents confounding • known and unknown potential confounders are evenly distributed

  8. Assess Validity and Applicability to my practice setting 1.Is the study a randomized control trial (RCT)? Yes (go on) No (stop) 2.Were the patients properly selected for the trial andrandomized with concealed assignment? Yes (go on) No (stop) 3.Were patients and study personnel “blind” to treatment? Yes (go on) No (pause) 4.Were the intervention and control groups similar at the start? (Check “Table 1” of most studies) Yes (go on) No (stop) 5.Was follow-up complete? ii. Were patients analyzed in the groups to which they were randomized (“intention-to-treat” analysis)?

  9. BEST – most valid technique • Central computer randomization DOUBTFUL • Envelopes, etc Ensuring Allocation Concealment NOT RANDOMIZED • Date of birth, alternate days, etc

  10. Do Not Confuse Allocation Concealment with Blinding • Allocation concealment seeks to prevent selection bias, protects assignment sequence before and until allocation, and can always be successfully implemented

  11. Do Not Confuse Allocation Concealment with Blinding(Cont’d) • Blinding seeks to prevent information bias, protects sequence after allocation, and cannot always be successfully implemented

  12. Assess Validity and Applicability to my practice setting 1.Is the study a randomized control trial (RCT)? Yes (go on) No (stop) 2.Were the patients properly selected for the trial and randomized with concealed assignment? Yes (go on) No (stop) 3.Were patients and study personnel “blind” totreatment? Yes (go on) No (pause) 4.Were the intervention and control groups similar at the start? (Check “Table 1” of most studies) Yes (go on) No (stop) 5.Was follow-up complete? ii. Were patients analyzed in the groups to which they were randomized (“intention-to-treat” analysis)?

  13. Placebo effect Trial in patients with chronic severe itching No treatment Trimeprazine tartrate Cyproheptadine HCL Treatment vs no treatment for itching

  14. Placebo effect Trial in patients with chronic severe itching No treatment Trimeprazine tartrate Cyproheptadine HCL Placebo Treatment vs no treatment vs placebo for itching Placebo effect - attributable to the expectation that the treatment will have an effect

  15. Blinding and Reporting • Usually reduces differential assessment of outcomes (information bias) • Authors should explicitly state who was blinded – and how. • Many investigators and readers consider a randomized trial as high quality simply because it is “double-blind,” as if double-blinding is the sine qua non of an RCT. • Trials not “double-blinded” should not automatically be deemed inferior trials.

  16. Blinding in randomised trials: hiding who got what • Double blinding prevents bias but is less important, than adequate allocation concealment. • open studies are more likely to favour experimental interventions over the controls and that studies that are not double-blinded can exaggerate effect estimates by 17% • Furthermore, in some trials, blinding cannot be successfully implemented, whereas allocation concealment can always be successfully implemented.

  17. Assess Validity and Applicability to my practice setting 1.Is the study a randomized control trial (RCT)? Yes (go on) No (stop) 2.Were the patients properly selected for the trial and randomized with concealed assignment? Yes (go on) No (stop) 3.Were patients and study personnel “blind” to treatment? Yes (go on) No (pause) 4.Were the intervention and control groups similar at thestart? (Check “Table 1” of most studies) Yes (go on) No (stop) 5.Was follow-up complete? ii. Were patients analyzed in the groups to which they were randomized (“intention-to-treat” analysis)?

  18. Significance tests for baseline differences

  19. Baseline data Effect of azathioprine on the survival of patients with primary biliary cirrhosis Christensen et al. Gastro 1985

  20. Baseline data Effect of azathioprine on the survival of patients with primary biliary cirrhosis Christensen et al. Gastro 1985

  21. Assess Validity and Applicability to my practice setting 1.Is the study a randomized control trial (RCT)? Yes (go on) No (stop) 2.Were the patients properly selected for the trial and randomized with concealed assignment? Yes (go on) No (stop) 3.Were patients and study personnel “blind” to treatment? Yes (go on) No (pause) 4.Were the intervention and control groups similar at the start? (Check “Table 1” of most studies) Yes (go on) No (stop) 5.Was follow-up complete? ii. Were patients analyzed in the groups to which they were randomized (“intention-to-treat” analysis)?

  22. How complete was the follow up? How many dropouts were there? • Conventionally, a 20% drop out rate is regarded as acceptable, but this depends on the study question. • Some regard should be paid to why participants dropped out, as well as how many. • It should be noted that the drop out rate may be expected to be higher in studies conducted over a long period of time. • A higher drop out rate will normally lead to downgrading, rather than rejection of a study.

  23. Bias: a one-sided inclination of the mind • Not random 40% • Not double-blind 17% • Duplicate information 20% • Small trials 30% • Poor reporting quality 25% Over-estimation of treatment effect

  24. Assess Validity and Applicability to my practice setting 1.Is the study a randomized control trial (RCT)? Yes (go on) No (stop) 2.Were the patients properly selected for the trial and randomized with concealed assignment? Yes (go on) No (stop) 3.Were patients and study personnel “blind” to treatment? Yes (go on) No (pause) 4.Were the intervention and control groups similar at the start? (Check “Table 1” of most studies) Yes (go on) No (stop) 5.Was follow-up complete? ii. Were patients analyzed in the groups to which they were randomized (“intention-to-treat” analysis)?

  25. Intention to treat Montorri V, Guyatt G. CMAJ 2001 165(10) p1340

  26. Intention to treat Montorri V, Guyatt G. CMAJ 2001 165(10) p1340

  27. Intention to treat High risk? Montorri V, Guyatt G. CMAJ 2001 165(10) p1340

  28. Assess Validity and Applicability to my practice setting 1.Is the study a randomized control trial (RCT)? Yes (go on) No (stop) 2.Were the patients properly selected for the trial and randomized with concealed assignment? Yes (go on) No (stop) 3.Were patients and study personnel “blind” to treatment? Yes (go on) No (pause) 4.Were the intervention and control groups similar at the start? (Check “Table 1” of most studies) Yes (go on) No (stop) 5.Was follow-up complete? ii. Were patients analyzed in the groups to which they were randomized (“intention-to-treat” analysis)?

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