EPI 225 Measurement in Clinical Research Fall 2009

EPI 225Measurement in Clinical ResearchFall 2009 Anita L. Stewart, Ph.D. Institute for Health & Aging University of California, San Francisco

Overview of Course • How to find, critique and select good self-report measures for your research • Weekly homework with weekly feedback • I am available for questions/discussion: • after class: 4:30-5:30 • by email • Focus on one concept of interest to you • Health outcome or a determinant of health • Measurable (need to find 2-3 measures to review)

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

Class 1Concept Development and Concept Definitions September 24, 2009

Overview of Class 1 • Role of concepts in measurement • Terminology, depicting concepts • Complexity of most concepts • Concept development methods • Importance of defining concepts prior to selecting existing measures

Typical Sequence of Developing New Self-Report Measures Develop/define concept Create item pool Pretest/revise Field survey Psychometric analyses Final measures

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

Concept/Construct • A variable that is relatively abstract as opposed to concrete • e.g. health status, stress, acculturation as opposed to height, body temperature • An abstraction based on observations of certain behaviors or characteristics • Cannot be assessed directly

Concept/Construct: Other Terms • Variable, latent trait, latent variable • Terms defined differently by different investigators/authors • Similar meaning • often used interchangeably

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

Measures of Concepts • Concepts are defined and operationalized in terms of observed indicators • Measures are “proxies” for the latent variables we cannot directly observe

Depicting Latent Variables and Measures CONCEPTVariable B CONCEPTVariable A Measure A Measure B

Depicting Latent Variables and Measures Health status Stress Perceived Stress Scale SF-36

Complexity of Concepts • By definition, due to abstract nature of concepts, most are complex • Hard to define • Multidimensional • Concepts within concepts • Some examples • Health • Quality of life • Interpersonal processes of care • Shared decision making

“Health” as a Concept or Latent Variable • What comes to mind when you think of the word “health”? Health

Some Common Terminology of “Health” • Health status • Health outcomes • Clinical status • Functional status • Functioning and well-being • Quality of life • Health-related quality of life

Definition Varies by Perspective Bench scientist Population scientist Clinician Health Individual

Perspectives on Health

Contradictory or Different Perspectives?

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)

Medical Outcomes Study (MOS) • Large study of patients with chronic disease • 1989 forward • Extensive measurement development part of MOS • Health, functioning, and well-being

MOS Framework: Physical and Mental Health are “Latent Variables” Physicalhealth Mental health

MOS Physical Health: Dimensions Physical Health Health perceptions Physicalfunctioning Role limitationsdue to physicalhealth Pain Energy &fatigue

MOS Physical Health: Dimensions, Sub-domains Physical Health Health perceptions Physicalfunctioning Role limitationsdue to physicalhealth Pain Energy &fatigue Painseverity Painfrequency

MOS Framework: Indicators of Physical and Mental Health Physical Mental IndicatorsHealthHealth Physical functioning X Pain X Energy/fatigue X X Sleep problems X X Cognitive functioning X Psychological distress/well-being X Role limitations due to physical health X Role limitations due to emotional problems X Health perceptions XX RD Hays and AL Stewart, Psychological Assessment: A Journal of Consulting and Clinical Psychology, 2:22-30, 1990.

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

Health as a continuum? Illness Perfecthealth

Health as a continuum? Less thanperfecthealth? Illness Perfecthealth

What are normal health states? Less thanperfecthealth?(normal) Illness (abnormal) Perfecthealth(abnormal)

Concept of Quality of Life • What comes to mind when you think of the word “quality of life”? Quality of Life

Quality of Life Terminology • Satisfaction with life “as a whole” • Well-being • Global well-being • Subjective well-being • Sense of well-being • Global happiness

Marriage Family life Health Neighborhood Friendships Job City Housing Standard of living National government Local government Dimensions/Domains of Quality of Life …. and many more

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

Shared Decision Making • How would you define “shared decision making”?

Shared Decision Making (DM):Some “Definitions” • MD propensity to encourage shared DM • Pt desire for active role in DM • MD encourages pts to take active role • Pt plays active role in deciding • Pt and MD share process of deciding on treatment

Varying Definitions Suggest Complex Concept MD propensity to encourage shared DM Process of shared decision making Patient desire for active role in DM

Concepts within Concepts MD propensity to encourage shared DM Process of shared decision making Patient desire for active role in DM

MD Propensity to Encourage Shared DM “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

Varying Definitions Suggest Complex Concept MD propensity to encourage shared DM Process of shared decision making Patient desire for active role in DM

Process of Shared Decision Making in ICU: Multidimensional • Information exchange • MD provides relevant medical information • Family member provides info on pt’s values/preferences • Deliberation • MD + family member discuss appropriate treatment options • Treatment decision • MD + family member clarify best treatment choice Doug White, MD, Dept Med, Div Pulmonary and Critical Care

Concept Development Methods • Primarily qualitative methods (formative research) • ethnography • direct observation • in-depth interviews • focus groups

Qualitative Methods to Develop Concepts and Measures • Focus groups, in-depth interviews • Data consist of words (text) • Useful for • Concept development • Item construction

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

Who Provides Input? • Patients or representatives of the population of interest • “Experts” with extensive clinical or personal experience with population of interest

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

EPI 225 Measurement in Clinical Research Fall 2009