randomized clinical trials I

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Integrated Dentistry I
Third Year

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  • 1. Randomized Controlled Trials Part 1
  • 2. Objectives • • • • Identify the RCT study design Discuss the various characteristics of RCTs Describe measures of effectiveness in RCTs Identify tools of critical appraisal of RCTs
  • 3. Study Types MAIN TYPES OF STUDY DESIGN Crosssectional Retrospective Cohort Observational Longitudinal Study Design Prospective Cohort Experimental Case-control
  • 4. Definition of RCTs • Is a prospective study design that randomly assigns participants into an experimental group and a control group.
  • 5. Definition of RCTs • Is a prospective study design that randomly assigns participants into an experimental group and a control group. • As the study is conducted, the only expected difference between the control and experimental groups is the outcome variable being studied.
  • 6. Definition of RCTs • Is a prospective study design that randomly assigns participants into an experimental group and a control group. • As the study is conducted, the only expected difference between the control and experimental groups is the outcome variable being studied. • It is the best design to assess causality.
  • 7. RCT Study Design Population sample Randomization & Allocation Concealment Intervention Disease Placebo NO Disease NO Disease Disease
  • 8. Characteristics of RCTs www.consort-statement.org/consort-statement
  • 9. Characteristics of RCTs • Prospective: – Allows the specific allocation and administration of intervention to a chosen population. – Increases the precision of the study compared to retrospective / observational data
  • 10. Characteristics of RCTs • Eligibility criteria for participants – A comprehensive description of the eligibility criteria used to select the trial participants is needed to help readers interpret the study. – a clear understanding of these criteria is one of several elements required to judge to whom the results of a trial apply (generalizability).
  • 11. Characteristics of RCTs • Settings and locations – crucial to judge the applicability and generalizability of a trial
  • 12. Characteristics of RCTs • Description of the interventions – Each intervention should be thoroughly described, including control interventions. – The intensity, duration, and frequency that best balances effectiveness and safety.
  • 13. Characteristics of RCTs • Defined pre-specified outcomes – What is the primary outcome? – How to measure it? – When to measure it? – Who will do the measurement?
  • 14. Characteristics of RCTs • How sample size was determined – The sample should be large enough to have a high probability (power) of detecting statistically significant and/or clinically important differences – The larger the sample the better we are at measuring the effect.
  • 15. Characteristics of RCTs • Randomization: – Every participant has an equal chance of being in either group – Ensures that all factors are equally distributed – Reduces selection and allocation biases – Eliminates the effect of confounders
  • 16. Characteristics of RCTs • Allocation Concealment. – The treatment allocation system should thus be set up so that the person enrolling participants does not know in advance which treatment the next person will get. – Happens before the intervention starts. – Could always take place.
  • 17. Characteristics of RCTs • Blinding (masking) – Withholding information about the assigned interventions from people involved in the trial who may potentially be influenced by this knowledge. – Participants and/or observers – Reduces observation bias. – Happens after the intervention starts. – Cannot always be implemented.
  • 18. Characteristics of RCTs • Statistical methods used to compare groups – It is essential to specify which statistical procedure was used for each analysis, and further clarification may be necessary in the results section of the report.
  • 19. Characteristics of RCTs • Statistical methods used to compare groups – It is essential to specify which statistical procedure was used for each analysis, and further clarification may be necessary in the results section of the report. – It is also important to describe details of the statistical analysis such as intention-to-treat analysis
  • 20. Critical Appraisal of the Evidence It is the process of systematically examining research to assess its validity and relevance before using it to make a clinical decision.
  • 21. Critical Appraisal of the Evidence • What is critical appraisal? It is the process of systematically examining research to assess its validity and relevance before using it to make a clinical decision. Importance to your patients (generalizability) The degree to which the results of the study are likely to be true, believable and free from bias
  • 22. Critical Appraisal Tools
  • 23. Revision 2003: information Mastery Working Group. Adapted from material developed at McMaster University
  • 24. Critically Appraise the Evidence Tools for Critical Appraisal Revision 2003: information Mastery Working Group. Adapted from material developed at McMaster University
  • 25. Critical Appraisal of the Evidence • Is the study valid? – Was the assignment of patients to treatment randomized? • Was the allocation to the different groups randomized? • How was randomization carried out? • Was it concealed?
  • 26. Critical Appraisal of the Evidence • Is the study valid? – Were all patients who entered the study properly accounted for at its conclusion? • Less than 30% of patients did not complete the study • Duration of study sufficient • Intention to treat analysis
  • 27. Critical Appraisal of the Evidence • Is the study valid? – Were patients, their physicians, and study personnel “blind” to treatment (masking)? • Single, double, triple blinding • How was it done? • Could there have been unblinding (unmasking)?
  • 28. Critical Appraisal of the Evidence • Is the study valid? – Were the groups similar at the start of the study? • Baseline prognostic factors (demographics, disease severity, etc) • If different, were they adjusted for?
  • 29. Critical Appraisal of the Evidence • Is the study valid? – Aside from the intervention, were the groups treated equally? • Co-intervention: – When participants take an intervention that has a similar effect as the intervention under study • contamination: – When participants in either of the groups receive the intervention intended for the other group • compliance
  • 30. Critical Appraisal of the Evidence • Is the study valid? – Overall, are the results of the study valid? • Yes… No
  • 31. Critical Appraisal of the Evidence • Is the study valid? • What are the results? • Can I apply the results locally?
  • 32. • To be continued…