PHC215

By Dr. Khaled Ouanes Ph.D.

E-mail: k.ouanes@seu.edu.sa

Twitter: @khaled_ouanes

INTRODUCTION TO

HEALTHCARE RESEARCH

METHODS

Experimental Studies

An experimental study assigns participants tointervention and control groups in order toexamine whether an intervention causes anintended outcome.

Because the researcher assigns participants toreceive a particular exposure, the exacttiming, dose, duration, and frequency of theexposure are known.

Framework

for an

Experimental

Study.

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

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

Defining Outcomes

Most experimental studies are superiority trialsthat aim to demonstrate that a new interventionis “better” than some type of control.

Because the term “better” can be defined in somany ways, the researcher must beforehandand carefully define what constitutes afavorable outcome for the experiment.

Types of Success

Examples of

Favorable

Outcomes

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?

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

Examples of Types of Controls

Examples of Types of Controls

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.

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

Blinding

There are 2 main cases:

In a single-blind study, participants are unaware oftheir exposure status

In a double-blind study, neither the participants northe persons assessing the participants’ health statusknow which participants are in the active and controlgroups.

Randomization

A variety of approaches can be used torandomly allocate participants to an activeintervention group or a control group:

Simple randomization

Block randomization

Stratified randomization

Examples of Types of

Randomization

Strata: Homogeneous

subgroups of

members in the population

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.

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

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.

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

Examples of Ethical Issues to

Consider When Planning an

Experimental Study

AnalysisExperimental 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.

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.

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.

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

Stratification of patients for efficacy can

substantially reduce the number

needed to treat for benefit.

Matthews, P. M. et al (2013 )

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.

Efficacy & Number Needed to Treat

(NNT)

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

Flow of Participants in an

Experimental Study

Ke

y C

ha

rac

terist

ics

of

Exp

erim

en

tal st

ud

ies

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

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

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

Test

Results

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

Qualitative Studies

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.

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

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.

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

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.

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.

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.

De

lph

i M

eth

od

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

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

Pro

gra

m E

va

lua

tio

n

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

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