Research Methodology / Experimental study

1. PHC215
By Dr. Khaled Ouanes Ph.D.
E-mail: k.ouanes@seu.edu.sa
Twitter: @khaled_ouanes
INTRODUCTION TO
HEALTHCARE RESEARCH
METHODS

2. Experimental Studies

3. An experimental study assigns participants to
intervention and control groups in order to
examine whether an intervention causes an
intended outcome.
Because the researcher assigns participants to
receive a particular exposure, the exact
timing, dose, duration, and frequency of the
exposure are known.

4. Framework
for an
Experimental
Study.

5. Randomized Controlled Trials (RCTs)
In a randomized controlled trial (RCT):
Some participants are randomly assigned to an
active intervention group
The remaining participants are assigned to a
control group
All participants from both groups are followed
forward in time to see who has a favorable
outcome and who does not

6. Describing the Intervention
The research plan should carefully define:
What the intervention will be
Where and how participants will receive the
intervention
When, how often, and for what duration
participants will receive the intervention
Eligibility and aptness criteria for participants

7. Defining Outcomes
Most experimental studies are superiority trials
that aim to demonstrate that a new intervention
is “better” than some type of control.
Because the term “better” can be defined in so
many ways, the researcher must beforehand
and carefully define what constitutes a
favorable outcome for the experiment.

8. Types of Success

9. Examples of
Favorable
Outcomes

10. Selecting Controls
Experimental studies usually assign some
participants to the active intervention and the
remainder to a control group.
SO WHAT TYPES OF CONTROLS CAN
WE HAVE?

11. 1. The most typical control is a placebo, an
inactive comparison that is similar to the
therapy being tested
2. Sometimes the new therapy is compared to
some existing “industry standard of care” or
other therapy
3. Sometimes varying doses and durations of a
therapy may be compared to one another
Selecting Controls

12. Examples of Types of Controls

13. Examples of Types of Controls

14. Hawthorne bias
Hawthorne effect: (observer effect) is a type of
reactivity in which participants in a study may
change their behavior for the better simply
because they know they are being observed
This may interfere with the accurate
measurement of the impact of the new
intervention.

15. Blinding
Blinding or masking:
Participants in an experimental study do not
know whether they are in the active intervention
group or the control group.
Blinding minimizes information bias

16. Blinding
There are 2 main cases:
 In a single-blind study, participants are unaware of
their exposure status
 In a double-blind study, neither the participants nor
the persons assessing the participants’ health status
know which participants are in the active and control
groups.

17. Randomization
A variety of approaches can be used to
randomly allocate participants to an active
intervention group or a control group:
Simple randomization
Block randomization
Stratified randomization

18. Examples of Types of
Randomization
Strata:
Homogeneous
subgroups of
members in
the population

19. Ethical Considerations
Experimental studies involve a particularly high
level of ethical risk because the researcher
assigns participants to exposures that the
participants do not choose and may have
been unlikely to encounter in normal life had
they not volunteered to participate in a
research project.

20. Ethical Principles
Clinical Equipoise or equipoise principal:
It provides the ethical basis for medical research
that involves assigning patients to different
treatments of a clinical trial. The term was first used
by Benjamin Freedman in 1987. It states that
experimental research should be conducted only
when there is genuine uncertainty about which
treatment will work better

21. Ethical Principles
Distributive justice: infers that the source
population must be an appropriate and non-
exploitative one
Beneficence (doing good) and non-maleficence
(do not harm): researchers must balance the
likely benefits and risks of the study. Otherwise the
study should not be conducted.

22. Respect for persons:
Participants must volunteer for a study without being
unduly influenced by the prospect of being
compensated for their participation
Participants must be able to understand what it
means to be a research subject, including the
possibility of being assigned to a control group
instead of the new intervention
Ethical Principles

23. Examples of Ethical Issues to
Consider When Planning an
Experimental Study

24. Analysis
Experimental studies use many of the same measures of
association that cohort studies do:
 Relative rates (RRs)
 Attributable risks (ARs, AR%s)
 Measures of survival
Experimental studies use these measures to examine
the impact of an assigned exposure on the likelihood of
having either a favorable or unfavorable outcome.

25. Analysis: Efficacy
Efficacy: the proportion of individuals in the control
group who experience an unfavorable outcome
who could have been expected to have a
favorable outcome had they been in the active
group instead of control.
A high efficacy is an indicator that an intervention
is successful.

26. Analysis: NNT
Number needed to treat (NNT): the expected number of
people who would have to receive a treatment to
prevent an unfavorable outcome in one person (or,
alternately stated, to achieve a favorable outcome in
one person)
A small NNT indicates a more effective intervention.

27.  If a drug is intended to prevent stroke and has an NNT
of 5, then 5 people have to take the drug for one year
(or some other chosen time span) to prevent one of
the 5 from having a stroke.
 If a drug has an NNT of 100, it means that 100 people
have to take the drug to prevent one of the 100 from
having a stroke.
Analysis: NNT

28. Stratification of patients for efficacy can
substantially reduce the number
needed to treat for benefit.
Matthews, P. M. et al (2013)

29. In the example depicted in the previous slide, 22% of
patients respond to a given treatment, so
approximately 5 patients need to be treated to benefit
one patient (NNT=5). If the population is stratified to
enrich the treated population with responders
(identified through testing), the number needed to treat
for benefit will decrease. In this example, a
stratification approach with 90% sensitivity and
specificity is assumed.

30. Efficacy & Number Needed to Treat
(NNT)

31. Analytic Frameworks
Treatment-received approach: limit analysis to
the participants who were fully compliant with
their assigned intervention
Treatment-assigned approach (intention-to-
treat approach): includes all participants even
if they were not fully compliant with their
assigned intervention

32. Flow of Participants in an
Experimental Study

33. KeyCharacteristicsof
Experimentalstudies

34. Screening & Diagnostic Tests
The goal of some studies is to compare two
tests that are supposed to measure the same
thing, such as comparing the results of an
antibody test for cancer to biopsy results

35. Sensitivity = Of those who have the disease,
what % test positive?
Specificity = Of those who do not have the
disease, what % test negative?
Screening & Diagnostic Tests

36. Positive predictive value (PPV) = Of those
who test positive, what % actually have the
disease?
Negative predictive value (NPV) = Of those
who test negative, what % actually do not
have the disease?
Screening & Diagnostic Tests

37. Test
Results

38. Tests of Agreement
 Tests of inter-observer agreement (concordance) can
be used to determine the extent of agreement between
two assessors who are evaluating the same study
participants
Example: a measurement known as the kappa statistic can
indicate whether two radiologists examining the same set of X-rays
reach the same conclusion about the presence or absence of a
fracture more or less often than can be expected by chance

39. Qualitative Studies

40. Qualitative Study Methods
A qualitative study looks for the themes and
meanings that emerge from the observation
and evaluation of a situation or context.
Researchers have intense contact with a
selected group of informants.

41. Examples of Approaches
 Phenomenology: seeks to understand how participants
understand, interpret, and find meaning in their own
unique life experiences and feelings
 Grounded theory: an inductive reasoning process that
uses observations to develop general theories that
explain human behavior
 Ethnography: aims to develop an insider’s view (an emic
perspective) of how members of a particular Ethnic or
cultural group see their world

42. Examples of Techniques
 In-depth and semi-structured interviews of individuals
use open-ended questions to explore viewpoints. The
interviewer is allowed to probe for more details about
any response in order to gain fuller understanding of the
participant’s experiences and perspectives.
 Interviews are often supplemented by other methods,
such as participant diaries or journals.

43. Focus groups of about 4 to 12 people are
moderated discussions led by a facilitator
from the research team. The facilitator
encourages participants to interact with
one another and to clarify their individual
and shared perspectives.
Examples of Techniques

44. Examples of Analytic Techniques
 The analysis of qualitative data usually involves coding
and classifying observations and deriving major and
minor themes from the groups of observations.
 Reports of the findings of qualitative studies often
incorporate quotations that express participants’
perspectives and experiences in their own words.

45. Consensus Methods
The goal of some studies is to identify areas of
consensus and areas of contention among
individuals who are experts on a particular
topic and/or a particular community or
organization.

46. Delphi Method
The Delphi method is a structured decision-making and
forecasting process in which participants engage in several
rounds of:
 Completing individual questionnaires
 A facilitator summarizing and sharing the responses
 Panelists reconsidering their perspectives after reflecting
on the opinions expressed by others
The goal is for each iteration to move the panel of experts
closer to agreement.

47. DelphiMethod

48. Program Evaluation
 Program evaluation includes a variety of approaches
for provide feedback about what is working well and
what can and should be improved
 The evaluation approach must match the goals of the
assessment
 After gathering evidence from a variety of sources,
practical suggestions are made based on the
conclusions of the assessment

49. Evidence is reviewed and categorized using a framework like
SWOT:
 Strengths (internal organizational strengths)
 Weaknesses (internal organizational limitations)
 Opportunities (external strengths)
 Threats (external limitations, which might be political, economic,
sociocultural, technological, environmental, or legal)
Program Evaluation

50. ProgramEvaluation

51. A similar process can be used as a
component of other forms of evaluative
research, such as:
Needs assessment.
Cost-effectiveness analysis
Health services research
Program Evaluation

52. PHC215
By Dr. Khaled Ouanes Ph.D.
E-mail: k.ouanes@seu.edu.sa
Twitter: @khaled_ouanes
HEALTHCARE RESEARCH METHODS
Based on the textbook of introduction to health research methods – K.H. Jacobsen