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RANDOMIZED CONTROLLED TRIAL

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Title: RANDOMIZED CONTROLLED TRIAL


1
RANDOMIZED CONTROLLED TRIAL
  • DR. SANJAY P. ZODPEY, MD, PhD
  • JULY 9-13, 2007
  • MGIMS-SEWAGRAM, IAPSM -EPIDEMIOLOGY COMMITTEE
    MAHARASHTRA CHAPTER

2
RANDOMIZED CONTROLLED TRIAL
  • Objectives
  • To understand the design issues related to RCTs
  • To know various steps involved in conduct of RCTs
  • To know various types of clinical trials

3
RANDOMIZED CONTROLLED TRIAL
  • Earlier public health measures were introduced on
    the basis of assumed benefits without subjecting
    them to rigorous testing
  • Last 30 to 40 years Evolution of Randomized
    Controlled Trials

4
  • CLINICAL TRIALS
  • Prospective study comparing the effect and value
    of one of more interventions against a control in
    human subjects with a given medical condition.
  • Measures causality in terms of the effect of an
    intervention If one alters the risk factor, does
    one alter the occurrence of the event/injury? 
  • "...the most definitive tool for evaluation of
    the applicability of clinical research.

5
RANDOMIZED CONTROLLED TRIAL
  • A true experiment, in which the researcher
    randomly assigns some patients to at least one
    maneuver (treatment) and other patients to a
    placebo, or usual treatment.
  • Key features
  • the classic way to evaluate efficacy or
    effectiveness of drugs (or exercise, diet,
    counseling)
  • patients are followed over time (prospective)
  • Properly done, an RCT can be used to determine
    cause and effect.

6
The ideal clinical trial is one that is
randomized and double-blind. RANDOMIZED,
DOUBLE-BLIND, CONTROLLED TRIAL is considered as
research design par excellence and GOLD
STANDARD amongst research designs with which
results of other studies are often compared.
Deviation from this standard has potential
drawbacks
7
  • A clinical trial must employ one or more
    intervention techniques.
  • These may be
  • Prophylactic
  • Diagnostic
  • Therapeutic agents
  • Devices
  • Regimens
  • Procedure

8
  • STEPS IN CONDUCT OF RCT
  • The protocol
  • Selecting reference and experimental populations
  • Randomization
  • Intervention
  • Follow up
  • Assessment

9
CLINICAL TRIAL
Improved
INTERVENTION GROUP
Not Improved
Population - - - - Of patients - - - - With the
- - - - Condition - - - -
SAMPLE
-- ALLOCATION
Improved
CONTROL GROUP
Not Improved
10
  • 1. The Protocol
  • Aims and objectives, Research questions,
    Selection criteria, Sample size, procedures up to
    the evaluation of outcome
  • Prevents bias and reduces the sources of errors
  • Preliminary test runs feasibility or
    operational efficiency

11
  • 2. Selecting Reference and Experimental
    Populations
  • Reference or target population - population to
    which the findings of the trial, if found
    successful, are expected to be applicable (eg.
    drugs, vaccines, etc.)
  • b. Experimental or study population - actual
    population that participates in the experimental
    study

12
  • Participants must fulfill the following criteria
  • Must give informed consent
  • Should be representative of the population
  • Should be qualified or eligible for the trial

13
SAMPLE SIZE
Clinical trials should have sufficient
statistical power to detect differences between
groups considered to be of clinical interest.
Therefore, calculation of sample size with
provision for adequate levels of significance and
power is essential part of planning.
14
  • 3. Randomization
  • Heart of the control trial
  • Procedure Participants are allocated into study
    and control groups
  • Eliminates bias and allows comparability

15
  • Both groups should be alike with regards to
    certain variables that might affect the outcome
    of the experiment
  • - Best done by using table of random numbers

16
RANDOMIZATION
Randomization tends to produce study groups
comparable with respect to known as well as
unknown risk factors, removes investigator bias
in the allocation of subjects and guarantees that
statistical tests will have valid significance
levels.
17
  • 4. Manipulation / Intervention
  • Deliberate application or withdrawal or reduction
    of a suspected causal factor
  • It creates an independent variable

18
  • 5. Follow Up
  • Implies examination of the experimental and
    control group subjects at defined intervals of
    time, in a standard manner, with equal intensity,
    under the same given circumstances
  • Attrition Inevitable losses to follow up

19
  • 6. Assessment
  • Positive results
  • Negative results
  • Biases Subject variation, Observer bias,
    Evaluation bias
  • Can be corrected by blinding

20
  • BLINDING
  • UNBLINDED, OPEN TRIAL
  • SINGLE BLIND
  • DOUBLE BLIND
  • TRIPLE BLIND

21
  • Some Study Designs
  • Concurrent Parallel Study Designs
  • 2. Cross Over Type of Study Designs

22
PERIOD 1
PERIOD 2
INTERVENTION
RANDOM ALLOCATION
SUBJECTS
CONTROL
CROSS OVER DESIGN
23
ETHICS IMPORTANT ISSUE IN CLINICAL TRIALS ETHICAL
CLEARANCE INSTITUTIONAL REVIEW BOARDS ETHICAL
COMMITTEES ICMR GUIDELINES FEDERAL/STATE
GUIDELINES INFORMED CONSENT
24
  • Types of Randomized Controlled Trials
  • 1. Clinical Trial
  • Concerned with evaluating therapeutic agent,
    mainly drugs
  • eg. Evaluation of beta-blockers in reducing
    cardiovascular mortality
  • Not all clinical trials are susceptible to being
    blinded

25
  • 2. Preventive Trials
  • Trial of primary preventive measures eg. Vaccines
  • - Analysis of preventive trials must result in
    clear statement about benefits to community, risk
    involved and cost to health

26
  • 3. Risk Factor Trials
  • Investigator intervenes to interrupt the usual
    sequence in the development of disease for those
    individuals who have risk factor for developing
    the disease
  • Primary prevention of CHD using clofibrate to
    lower serum cholesterol

27
  • 4. Cessation Experiment
  • An attempt is made to evaluate the termination of
    a habit which is considered to be causally
    related to disease
  • Cigarette smoking and lung cancer

28
  • 5. Trials of Etiological Agents
  • To confirm or refute an etiological hypothesis
  • 6. Evaluation of Health Services
  • Domiciliary treatment of PTB was as effective as
    more costlier hospital or sanatorium treatment

29
MULTICENTER TRIALS
  • Reasons for Multi-center Trials
  • 1. To recruit necessary number of subjects within
    a reasonable time.
  • May assure a more representative sample of the
    study or target population
  • Enables investigators with similar interest and
    skills to work together on a common problem

30
PHASES OF TRIALS
  • Phase I Trials
  • Initial studies to determine the metabolism and
    pharmacologic actions of drugs in humans, the
    side effects associated with increasing doses,
    and to gain early evidence of effectiveness may
    include healthy participants and / or patients

31
PHASES OF TRIALS
  • Phase II Trials
  • Controlled clinical studies conducted to evaluate
    the effectiveness of the drug for a particular
    indication or indications in patients with
    disease or condition under study and to determine
    the common short-term side effects and risks

32
PHASES OF TRIALS
  • Phase III Trials
  • Expanded controlled and uncontrolled trials after
    preliminary evidence suggesting effectiveness of
    the drug has been obtained, and are intended to
    gather additional information to evaluate the
    overall benefit-risk relationship of the drug

33
PHASES OF TRIALS
  • Phase IV Trials
  • Post-marketing studies to delineate additional
    information including the drugs risks, benefits,
    and optimal use
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