1 epi 225 measurement in clinical research fall 2008 anita l. stewart, ph.d. institute for health...
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EPI 225
Measurement in Clinical Research
Fall 2008
Anita L. Stewart, Ph.D.Institute for Health & Aging
University of California, San Francisco
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Overview of Entire Class How to identify, critique and select good
measures for your research Weekly homework (paper copy) w/weekly
feedback Two discussion sessions (optional)
– 2:15-3:00 and 4:30-5:00 Focus on one concept of interest to you
– Health dimension or a determinant of health– Measurable (need to find 2-3 measures to review)
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Importance of Appropriate Measures
Inadequate measures can result in: Conceptual inadequacy Poor data quality (e.g. missing data) Poor variability Poor reliability and validity Inability to detect associations
– correlations, mean differences
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Class 1
Concept Development and Concept Definitions
September 18, 2008
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Overview of Class 1
Role of concepts in measurement Complexity of most concepts Concept development methods Importance of defining concepts prior to
selecting existing measures
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Typical Sequence of Developing New Self-Report Measures
Develop concept
Create item pool
Pretest/revise
Field survey
Psychometric analyses
Final measures
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Typical Sequence of Developing New Self-Report Measures
Develop concept
Create item pool
Pretest/revise
Field survey
Psychometric analyses
Final measures
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Process of Selecting Good Measures for Your Studies
Define concept (variable)
Identify potential measures
Review measures’ properties--conceptual adequacy
--psychometric adequacy
Pretest best 1-2 measures
Select final measure
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Process of Selecting Good Measures for Your Studies
Define concept (variable)
Identify potential measures
Review measures’ properties--conceptual adequacy
--psychometric adequacy
Pretest best 1-2 measures
Select final measure
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Concept/Construct
A variable that is relatively abstract as opposed to concrete– e.g. health status, stress, acculturation vs.
height, body temp An abstraction based on observations of
certain behaviors or characteristics Cannot be assessed directly
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Concept/Construct: Other Terms
Variable, latent trait, latent variable Terms defined differently by different
investigators/authors Similar meaning
– often used interchangeably
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Latent Variable or Trait
Latent - present but not visible, unobservable
Latent trait - unobservable set of characteristics that can be empirically inferred and estimated through answers to a set of questions
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Measures of Concepts
Concepts are defined and operationalized in terms of observed indicators
Measures are “proxies” for the latent variables we cannot directly observe
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Depicting Latent Variables and Measures
CONCEPTVariable A
Measure A
CONCEPTVariable B
Measure B
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Depicting Latent Variables and Measures
Stress
Perceived Stress Scale
Health status
SF-36
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Overview of Class 1
Role of concepts in measurement Complexity of most concepts Concept development methods Importance of defining concepts prior to
selecting existing measures
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Complexity of Concepts
By definition, due to abstract nature of concepts, most are complex – Hard to define
– Multidimensional» Concepts within concepts
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Example: Shared Decision Making
How would you define “shared decision making”?
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Shared Decision Making (DM): Some “Definitions”
MD propensity to encourage shared DM MD encourages pts to take active role MD responsive to pt preferences regarding
participating in decision Pt desire for active role in DM Pt plays active role in deciding Pt and MD share process of deciding on
treatment
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Varying Definitions Suggest Complex Concept
Process of shared decision making
MD propensityto encourage shared DM(participatory DM style)
Patient desire for shared DM
(active patient orientation)
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Varying Definitions Suggest Complex Concept
Process of shared decision making
MD propensityto encourage shared DM(participatory DM style)
Patient desire for shared DM
(active patient orientation)
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Participatory Decision-Making Style
Propensity (of physicians) to– offer pts choices among treatment options
– to give pts a sense of control of care
– to give pts a sense of responsibility for care
Kaplan SH et al. Ann Int Med, 1996;124:497
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Varying Definitions Suggest Complex Concept
Process of shared decision making
MD propensityto encourage shared DM(participatory DM style)
Patient desire for shared DM
(active patient orientation)
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Process of Shared Decision Making in ICU: Multidimensional
Information exchange – MD provides relevant medical information – Surrogate provides information on pt’s values/preferences
Deliberation– MD and surrogate discuss which treatment option is most
appropriate given pt’s values and condition Treatment decision
– MD and surrogate clarify what they think is correct treatment choice
Doug White, MD, Dept Med, Div Pulmonary and Critical Care
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“Health” as a Concept or Latent Variable
What comes to mind when you think of the word “health”?
Health
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Some Common Terminology of “Health”
Health indicators Health status Health outcomes Clinical status Functional status Functioning and well-being Quality of life Health-related quality of life
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Definition Varies by Perspective
Health
Bench scientist
Individual
Populationscientist Clinician
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Perspectives on Health Bench
Scientist Clinician Individual
Molecular, genetic, cellular X ??Anatomic, physiologic signs XSymptoms X XDiagnosed conditions X XSeverity of conditions X XFunctioning in daily life XWell-being X
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Contradictory or Different Perspectives?
Patient 1 Signs of illness (MD)
Perception: very good health (pt)
Patient 2 No signs of illness (MD)
Perception: poor health (pt)
Patient 3 Cellular abnormality (lab)
No signs of illness (MD)
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Dimension, Domain, Sub-domain, Component
Terms somewhat interchangeable Dimension: a distinct component of a
multidimensional construct that can be theoretically or empirically specified (e.g., physical and mental health)
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MOS Framework: Physical and Mental Health are “Latent Variables”
Physicalhealth
Mentalhealth
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Physical Health
MOS Physical Health: Dimensionality
Physicalfunctioning
Physicalfunctioning
Health perceptions
Health perceptions
PainPainEnergy &
fatigueEnergy &
fatigue
Role limitationsdue to physical
health
Role limitationsdue to physical
health
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Physical Health
MOS Physical Health: Dimensionality
Physicalfunctioning
Physicalfunctioning
Health perceptions
Health perceptions
PainPainEnergy &
fatigueEnergy &
fatigue
Role limitationsdue to physical
health
Role limitationsdue to physical
health
Painfrequency
Painseverity
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MOS Framework: Indicators of Physical and Mental Health
Physical Mental
Indicators Health Health Physical functioning X Pain X Energy/fatigue X X Sleep problems X X Cognitive functioning X Psychological distress/well-being X Social activity limitations due to health X X Role limitations due to physical health X Role limitations due to emotional problems X Current health perceptions X X
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What is Perfect Health?
An ideal toward which people are oriented – not a state they expect to attain
“A healthy person is someone who has been inadequately studied” (p. 31)
AC Twaddle, The concept of health status, Soc Sci Med 1974;8
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Health as a continuum?
Illness Perfecthealth
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Health as a continuum?
Illness Perfecthealth
Less thanperfecthealth?
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What are normal health states?
Illness
(abnormal)
Perfecthealth
(abnormal)
Less thanperfecthealth?
(normal)
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Concept of Quality of Life
What comes to mind when you think of the word “quality of life”?
Quality of Life
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Quality of Life Terminology
Satisfaction with life “as a whole” Well-being Global well-being Subjective well-being Sense of well-being Global happiness
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Dimensions/Domains of Quality of Life
Marriage Family life Health Neighborhood Friendships Job
City Housing Standard of living National government Local government
…. and many more
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Health-Related Quality of Life?
Domains of life relevant to health, disease, and medical care
Well-being– Physical (malaise, symptoms)– Mental (psychological well-being)
Functioning– Limited in activities because of health problems
or treatments
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Overview of Class 1
Role of concepts in measurement Complexity of most concepts Concept development methods Importance of defining concepts prior to
selecting existing measures
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Concept Development Methods
Primarily qualitative methods (formative research)
Many types– ethnography, participant-observation, direct
observation, focus groups, in-depth interviews
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Qualitative Methods to Develop Concepts and Measures
Focus groups, in-depth interviews Data consist of words (text), not numbers Useful for
– Concept development
– Item construction
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Focus Groups
Open-ended guided group discussion with probing of responses
Listen to perspective of likely “subjects”– How they discuss “concept” in their own
words Participants stimulate comments of others
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Who Provides Input?
Patients or representatives of the population of interest
“Experts” with extensive clinical or personal experience with population of interest
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Focus Group Methods
Led by experienced moderator– usually 1 - 2 hours
Purposeful sampling of 6-10 homogenous participants per group
Interview guide – set of open ended questions
Audio-record and transcribe discussion
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Example: Interview Guide for Concept of Depression in Diverse Groups
Sample: White, South Asian, and Black Caribbean individuals in U.K.
Questions: – What does the word depression mean to you?
– Do you consider depression to be an illness?
– What do you think might cause depression?
V Lawrence et al., Gerontologist, 2006;46:23-32
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Advanced Concept Development Methods
Iterative process Integrating qualitative and quantitative
methods (“mixed methods”)
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Nine Step Iterative Sequence to Develop Structured Measures
Focus groups In-depth interviews Input from quantitative studies Develop preliminary items Review by expert panel Cognitive interview pretest Pilot study Nationwide survey Psychometric testing
N Krause, J Geront: Soc Sci, 2002;57B:S263-274
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Iteratively Refine Concept Based on Qualitative Methods
Develop concept
Create item pool
Pretest/revise
Field survey
Psychometric analyses
Final measures
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Mixed Methods: Iteratively Refine Concept Based on Quantitative Results
Develop concept
Create item pool
Pretest/revise
Field survey
Psychometric analyses
Final measures
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Concept Development: Interpersonal Processes of Care
Interpersonal processes between physicians and patients, emphasis on vulnerable patients
Two “rounds” of concept development Round one – initial concept and items based on:
– Review of literature– Satisfaction with care measures content– Clinical experience of investigators
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Initial Hypothesized “Multidimensional” Conceptual Framework of IPC
I. COMMUNICATION III. INTERPERSONAL STYLE General clarity Friendly, courteous Elicitation/responsiveness Respectful to pt issues Perceived discrimination Explanations of Cultural sensitivity -condition Emotional support -self care -process of care Empowerment II. DECISION MAKING Responsiveness to patient preferences Consideration of ability to comply
Stewart et al., Milbank Mem Q,1999 in readings, Table 1
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Concept Development: Interpersonal Processes of Care (cont)
Initial concept modified slightly after measurement analyses
Differences:– No cultural sensitivity scale
– Content of many dimensions changed
Stewart et al., Milbank Mem Q, 1999, Tables 2 and 3
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Developing “Round Two” IPC Concept
Draft IPC II
conceptualframework
IPC Round One frameworkin Milbank Quarterly
19 new focus groups -African American, Latino,and White adults
Updated literature review of quality of care in diverse groups
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IPC “Round Two” Hypothesized Conceptual Framework
I. COMMUNICATION III. INTERPERSONAL STYLE General clarity Friendly, courteous Elicitation/responsiveness Respectful Explanations of Perceived discrimination --condition Cultural sensitivity --processes of care Emotional support --self-care Empowerment Office staff: friendly II. DECISION MAKING courteous, respectful Responsive to pt preferences Consider ability to comply
Stewart et al., Health Serv Res, 2007;42:3(Part I):1235-1255, Table 1
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Round Two: Interpersonal Processes of Care Concept
Develop concept
Create item pool
Pretest/revise
Field survey N=1,664
Psychometric analyses
Final measures
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Final “Round Two” Conceptual Framework
I. COMMUNICATION III. INTERPERSONAL STYLE General clarity Emotional support Hurried, distracted Respectful Elicited concerns Assumed SES Explained results Discriminated due to R/E Explained medications Disrespectful office staff II. PATIENT-CENTERED DECISION MAKING Consider ability to comply Decided together Stewart et al., Health Serv Res, 2007 - Fig 1
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Concept Development: Cultural Sensitivity of Physicians
For minority patients and those with limited English proficiency– Sensitivity of providers to their cultural
perspective hypothesized to be an important aspect of interpersonal processes of care
Hypothesized scale did not work in either of our IPC studies
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New Qualitative Analyses
19 focus groups of ethnically diverse adults– Groups homogeneous on ethnicity, language
(English/Spanish), gender, and age Two open-ended focus group questions:
– What does the word culture mean to you?– What do your doctors understand about your culture
that might affect your visits? Transcripts analyzed using qualitative methods
Nápoles-Springer et al. Health Expectations. 2005;8:4-17.
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Results: Multiple Dimensions of Cultural Factors Affecting the Medical Encounter
Examples … Values, beliefs, and
attitudes Communication
including sensitivity to language access
Complementary and alternative medicine
Privacy and modesty Ethnic concordance
of physician and patient
Empowerment and submissiveness
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Overview of Class 1
Role of concepts in measurement Complexity of most concepts Concept development methods Importance of defining concepts prior to
selecting existing measures
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Process of Selecting Good Measures for Your Studies
Define concept (variable)
Identify potential measures
Review measures’ properties--conceptual adequacy
--psychometric adequacy
Pretest best 1-2 measures
Select final measure
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Process of Selecting Good Measures for Your Studies
Define concept (variable)
Identify potential measures
Review measures’ properties--conceptual adequacy
--psychometric adequacy
Pretest best 1-2 measures
Select final measure
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State Role of Concept in Your Research
Evaluate intervention (outcome) Predict an outcome Describe population Predict future event (e.g. health, use of
emergency care) Covariate
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Define Concept for Your Research
Define it first from your point of view – How you would define it based on your experience
and understanding of your research question For dependent variables
– Describe how intervention or independent variables might affect it - types of changes you expect
For independent (predictor) variables– Describe how it might be predictive
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Importance of Defining Concept Your Way
Distinction between “label” or name of a measure and what it actually contains
May find “good” measure of your concept with the right label– But mismatched
» Measures something different than you need» Measures only part of what you need (missing
elements)
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Four Physical Functioning Measures: Content Areas
AIMS MOS HAQ SIP
Walking X X X X
Climbing stairs or steps X X X X
Bending, kneeling X X X X
Lifting, carrying X
Getting out of bed X
Bathing X X X
Running errands X
Opening jars X
Vigorous activities X X X
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Four Depression Measures: Content Areas
CES-D20
HRSD21
Beck21
GDS15
Personal functioning, behavior
-sleep problems, substance abuse
3 3 4 3
Social functioning, behavior -cut down work, withdraw
1 1 0 0
Physical symptoms
-fatigue, low libido
2 8 5 1
Emotional status
-depressed mood, lonely, happy
9 3 4 5
Cognitions/perceptions
-sense of failure, suicidal thoughts
5 6 8 6
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Four Depression Measures: Content Areas as Concept Definitions?
CES-D20
HRSD21
Beck21
GDS15
Personal functioning, behavior
-sleep problems, substance abuse
3 3 4 3
Social functioning, behavior -cut down work, withdraw
1 1 0 0
Physical symptoms
-fatigue, low libido
2 8 5 1
Emotional status
-depressed mood, lonely, happy9 3 4 5
Cognitions/perceptions
-sense of failure, suicidal thoughts
5 6 8 6
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Homework: Define Concept
Summarize briefly a key research question of interest to you
Choose one key concept and describe its role (e.g. dependent variable)
Define concept from your point of view– What are the dimensions of your
definition?