2 Randomized Controlled Trial Aim: testing medicines or medical proceduresuse randomized controlthe most reliable form of scientific evidenceeliminates all forms of spurious causalitySpecial condition:randomized clinical trial (RCT)clinical trialThe basic idea: treatments are allocated to subjects at randomdifferent treatment groups are'statistically equivalent'
3 Clinical Trial Disease Treatment No Yes Sample Placebo No Yes PopulationRandomselectionIn clinical trials, the investigator applies a treatment (intervention) and observes the effect on an outcome.The major advantage of a trial over an observational study is the ability to demonstrate causality. Randomly assigning the intervention can eliminate the influence of confounding variables, and blinding the administration decreases bias ascertainment.Blindedadministration
4 Randomized Controlled Trial STEPS: Selection of participantsRandom allocation to treatment or control armBlinding of treatment or control to patient and/or clinician
6 Randomized Controlled Trial RANDOMIZATION To ensure even distribution of confounding factors among the two groups
7 Randomized Controlled Trial BLINDING To minimize placebo effectCan not be applied in particular conditionBlindingKnowledge of treatment assignmentPatientClinicianInvestigatorNoneYesSingleNoDoubleTriple
9 Randomized Controlled Trial ETHICAL ISSUE Adopt new treatment without conducting experimental trialContinue a trial if treatment harmfulWhat if treatment obviously effective?Conduct a trial with marginal benefit
10 Randomized Controlled Trial AdvantagesDemonstrate causalityRandomization: eliminate the influence of confounding variablesBlinding : decreases biasDisadvantagesExpensiveComplianceSelective populationEthical issue
11 Randomized Controlled Trial PHASES Developed by FDA for approval of new treatmentAfter experimental trial in vitro and in animalTesting a new treatment in small group of volunteer (usually healthy people)Determine: safe dose-range, side-effectTesting to a larger group (usually RCT)Determine effectiveness, tolerability, and safety
12 Randomized Controlled Trial PHASES (cont…) Test the treatment in a larger group of patientsConfirm effectivenessMonitor side effectComparing with ‘old’ treatmentCollect information for safe use of drugPost marketingEffect on different populationSide-effect
13 CONSIDER……. In preparing or using the results of RCT, Quality: Reliability: replicable under ideal conditionValidity: the degree to which a study reaches a correct conclusion, depends on:MethodSampleBias: systematic distortion of statistical resultSelection biasObserver biasRecall biasReporting biasPublication bias
14 Clinical TrialStudy population : New VP shunt patients in NS DepartmentSample : Group 1 : VP shunt patients + AGroup 2: VP shunt patients + BVariable :InfectionType of AntibioticDummy table :InfectionYesNoAB
15 Clinical Trial Outcome Treatment No Yes Sample Placebo (treatment B) CONCLUSIONPlacebo(treatment B)NoYesPopulationRandomselectionIn clinical trials, the investigator applies a treatment (intervention) and observes the effect on an outcome.The major advantage of a trial over an observational study is the ability to demonstrate causality. Randomly assigning the intervention can eliminate the influence of confounding variables, and blinding the administration decreases bias ascertainment.Blindedadministration
16 Clinical Trial The effect of a therapy: OUTCOMEInfectionNo infectionTotalTherapyaba+bControlcdc+da+cb+da+b+c+dThe effect of a therapy:Relative risk, risk reduction, relative risk reduction, NNTThe precision :P < 0.05; 95% confidence interval
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