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Randomized Controlled Trial Aim: testing medicines or medical procedures use randomized control the most reliable form of scientific evidence eliminates.

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Presentation on theme: "Randomized Controlled Trial Aim: testing medicines or medical procedures use randomized control the most reliable form of scientific evidence eliminates."— Presentation transcript:

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2 Randomized Controlled Trial Aim: testing medicines or medical procedures use randomized control the most reliable form of scientific evidence eliminates all forms of spurious causality Special condition: randomized clinical trial (RCT) clinical trial The basic idea: treatments are allocated to subjects at randomsubjectsrandom  different treatment groups are 'statistically equivalent'

3 Clinical Trial Treatment Placebo Population Sample No Yes NoYes Disease Randomselection Blindedadministration

4 Randomized Controlled Trial STEPS: Selection of participants Random allocation to treatment or control arm Blinding of treatment or control to patient and/or clinician

5 Randomized Controlled Trial SAMPLING: Sample size calculation Inclusion/exclusion criteria Informed consent

6 Randomized Controlled Trial RANDOMIZATION To ensure even distribution of confounding factors among the two groups

7 Randomized Controlled Trial BLINDING To minimize placebo effect Can not be applied in particular condition Blinding Knowledge of treatment assignment PatientClinicianInvestigator NoneYes SingleNoYes DoubleNo Yes TripleNo

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9 Randomized Controlled Trial ETHICAL ISSUE Adopt new treatment without conducting experimental trial Continue a trial if treatment harmful What if treatment obviously effective? Conduct a trial with marginal benefit

10 Randomized Controlled Trial Advantages Demonstrate causality Randomization: eliminate the influence of confounding variables Blinding : decreases bias Disadvantages Expensive Compliance Selective population Ethical issue

11 Randomized Controlled Trial PHASES Developed by FDA for approval of new treatment After experimental trial in vitro and in animal 1. Testing a new treatment in small group of volunteer (usually healthy people) Determine: safe dose-range, side-effect 2. Testing to a larger group (usually RCT) Determine effectiveness, tolerability, and safety

12 Randomized Controlled Trial PHASES (cont…) 3. Test the treatment in a larger group of patients Confirm effectiveness Monitor side effect Comparing with ‘old’ treatment Collect information for safe use of drug 4. Post marketing Effect on different population Side-effect

13 CONSIDER……. In preparing or using the results of RCT, Quality: Reliability: replicable under ideal condition Validity: the degree to which a study reaches a correct conclusion, depends on: Method Sample Bias: systematic distortion of statistical result Selection bias Observer bias Recall bias Reporting bias Publication bias

14 Clinical Trial Study population : New VP shunt patients in NS Department Sample : Group 1 : VP shunt patients + A Group 2: VP shunt patients + B Variable: Infection Type of Antibiotic Dummy table : Infection YesNo A B

15 Clinical Trial Treatment Placebo (treatment B) Population Sample No Yes NoYes Outcome Randomselection Blindedadministration CONCLUSION

16 Clinical Trial OUTCOME Infection No infection Total Therapyab a+ba+ba+ba+b Controlcd c+dc+dc+dc+d Totala+cb+da+b+c+d The effect of a therapy: Relative risk, risk reduction, relative risk reduction, NNT The precision : P < 0.05; 95% confidence interval

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