Integrated Dentistry I Third Year

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

17. 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.

18. 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.

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.

20. 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

23. 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.

24. 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

25. Critical Appraisal Tools

27. Revision 2003: information Mastery Working Group. Adapted from material developed at
McMaster University

28. Critically Appraise
the Evidence
Tools for Critical Appraisal
Revision 2003: information Mastery Working Group. Adapted from material developed at
McMaster University

30. 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?

31. 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

32. 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)?

33. 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?

34. 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

35. Critical Appraisal of the Evidence
• Is the study valid?
– Overall, are the results of the study valid?
• Yes… No

36. Critical Appraisal of the Evidence
• Is the study valid?
• What are the results?
• Can I apply the results locally?

37. • To be continued…