Conceptual Frameworks of Health and Introduction to Conceptual Issues in Diverse Populations

Conceptual Frameworks of Health and Introduction to Conceptual Issues in Diverse Populations Anita L. Stewart, Ph.D. Anna Nápoles-Springer, Ph.D. University of California, San Francisco Clinical Research with Diverse Communities EPI 222, Spring 2002

Overview • What are conceptual frameworks and why are they needed? • Conceptualizing health in general • How are variables related to health? • Issues of conceptualizing health and health-related concepts in diverse populations

What is a Conceptual Framework? • A description of the research problem that: • Specifies and defines variables of interest (predictors, covariates and outcomes) • Describes the hypothesized relationships among variables to be tested • Is based on theory and/or empirical data

Why do we Need Conceptual Frameworks? They … • Provide rationale and theoretical basis for research questions/hypotheses • Guide the variables/measures selected to address research question, the analysis plan, or program evaluation • Help identify potential covariates that need to be measured • Are critical for understanding complex relationships, as in health disparities

Using Frameworks to Study Complex Processes That Can Affect Health Helps you to: • Clearly and comprehensively define and operationalize the constructs of interest • Identify conditions under which specific constructs operate on health • Evaluate different aspects of constructs (e.g. control, social support) separately to determine what aspects (individual, organizational, environmental, or social) are important under various conditions

Conceptualizing Health in General • Terminology • Conceptual frameworks • Categories of health • Relationships among health domains • Conceptualizing a health domain

Terminology • Health status • Health indicators • Health outcomes • Functional status • Functioning and well-being • Quality of life • Health-related quality of life

More Terminology: Functional Status and Functioning • Functional status • Functioning • Functional limitations • Disability • Handicap • Impairment • Physical fitness • Physical functioning • Major activity limitations

Individual Clinicianor Proxy Anatomic, physiologic, biochemical X Diagnosed physical/mental conditions XX Severity of conditions XX Functioning in daily life X Well-being (emotional & physical) X Perspectives on Health

Functioning and Well-being: Healthfrom the Patient’s Perspective • Functioning: Ability to perform behaviors and activities of daily life Usually observable • Well-being: Internal, subjective feelings and perceptions Physical and emotional

Conceptualizing Health in General • Terminology • Conceptual frameworks • Categories of health • Relationships among health domains • Conceptualizing a health domain

World Health Organization Definition of Health Status “…physical, mental, and social well-being…” “…not merely the absence of disease or infirmity.”

1. Symptoms 2. Functional status 3. Role activities 4. Social functioning 5. Emotional status 6. Cognition 7. Sleep and rest 8. Energy and vitality 9. Health perceptions 10. General life satisfaction Conceptual Framework: Marilyn Bergner Bergner M, Med Care, 1989;27:S148

Medical Outcomes Study Framework Physical Mental Indicators 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 - physical health X Role limitations - emotional problems X Current health perceptions X X Stewart AL, MOS Framework. In Stewart and Ware, 1992.

Key Point: What Are Conceptual Frameworks of Health? • Are they just a lot of categories? • With different investigators defining different categories? • Is there some order among the categories? • Most are static • no flow or dynamic pattern of relationships • Very few conceptual frameworks of relationships among variables

Functional Limitations Pathology Impairments Disability The Disablement ProcessVerbrugge and Jette Diagnoses of diseases, injury, congenital, development- al condition Abnormalitiesin specific body systems Restrictions in basic physical and mental actions Difficulty doing activities of daily lifedue to a health problem Soc Sci Med, 1994;38:1-14

Biological and Physio- logical Variables Symptom Status Functional Status General Health Percep- tions Overall Quality of Life Conceptual Model of Patient Outcomes:Wilson and Cleary Wilson, IB and Cleary, PD, JAMA, 1995

Conceptualizing HRQL in General • Terminology of HRQL • Conceptual frameworks of HRQL • Categories of health • Relationships among health domains • Conceptualizing a HRQL domain

Defining a Domain of Health-Related Quality of Life Involves Specifying • Content area • of domains and subdomains • Response dimensions • Time frame

Sample Content Area: Physical Functioning Domain • Walking • Running • Climbing stairs, hills • Bending, stooping • Turning head • Lifting, reaching, carrying • Getting in/out of a chair, car • Dexterity

Content Areas of Physical Functioning in Four Measures AIMS MOS HAQSIP Walking . . . . . . . . . . . . . X X X X Climbing stairs, 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

State/level Evaluative Comparative State or level of behavior of feeling - Frequency of pain - Amount of difficulty walking Value attached to level or state - Satisfaction with health - Bothersomeness of symptom Comparison to prior time, other persons Types of Response Dimensions

State/level Evaluative Able/unable to do Extent of limitation Amount of difficulty Need for help Speed of completing defined task Satisfaction with level Possible Response Dimensions for Physical Functioning

Example: State/Level Responses for Three Physical Functioning Measures Do you have any trouble... walking one block… ? (AIMS) Yes or No Does your health limit you… in walking one block? (MOS) Yes, limited a lot Yes, limited a little No, not limited at all Are you able to… walk one block? (HAQ) Without any difficulty With some difficulty With much difficulty Unable to do

Past: Present: No time frame: Average experience over some previous time period (6 months, 3 months, 4 weeks, etc) Current status, how they are now Time frame not specified (assumes “in general”) Specify Time Frame

Activities in Which a Person Might be Limited • Self care Bathing, dressing, eating, using toilet • Instrumental Shopping, laundry, cooking, work around the house, getting around the community • Role Work, caregiving, volunteering family roles • Social Getting together with others • Physical Walking, exercise, sports • Recreational Hobbies, recreational activities, going outdoors

Ability to Perform Activities: Interaction Between HRQL and Nature of Activities Functioning and well-being • Physical functioning • Cognitive functioning • Psychological distress/well-being • Fatigue • Pain Ability to perform complex activities Nature of activities • Location • Complexity • Opportunity to do them

What’s In A Name? • Domain or variable label may not mean what you think it means • Essential to examine content areas of a measure with any label to see how that measure is defined

Summary of Issues Conceptualizing Health • Much variation in definitions of health and health-related concepts • don’t judge a measure by its label • Content and response dimensions are part of definition • Clarify conceptual framework and concept definitions prior to beginning any study • Consider contextual factors that may affect domains and subdomains of interest • Consider interrelationships among variables

How are VariablesRelated to Health? • A predictor or independent variable can be: • unrelated to the outcome variable • directly related to the outcome variable • indirectly related to the outcome variable • jointly related with another variable to the outcome variable • confounded by a covariate

Mediators • Mediator variable • Is on the “causal pathway” between the independent and dependent variable • The independent variable causes the mediating variable, which then causes the outcome

Mediators A C A is directly related to C B A C A is indirectly related to C B mediates the relationship between A and C

Test of 3 equations: A B A C A C B To assess mediation hypothesis (A B C) A must independently predict B & C and B must predict C Compare effects of A on C when B is, and is not, controlled Effects of A on C when controlling for B should be substantially less than when not controlling for B Assessing Mediation with Regression

Why Assess Potential Mediators? • Most available population data on health determinants usually involve distal (removed) causes of illness (e.g. income, education) • Distal determinants exert their effects through more proximate determinants (mechanisms) • Proximate determinant may provide greater potential for interventions

Distal Social Determinant (poverty) Health Outcome (infectious disease) Proximate Determinant (malnutrition) Distal Social Determinant (poverty) Health Outcome (infectious disease) Distal and Proximate Determinants of Health: Identifying Mechanisms

Distal Social Determinant (poverty) Health Outcome (infectious disease) Why Assess Potential Mediators? • Improperly adjusting for the effects of proximate determinants may result in underestimating the effects of the distal determinants Proximate Determinant (malnutrition)

Moderators • Moderator variable • Affects the relationship between 2 variables • the effect of the independent variable on the dependent variable depends on the level of a third variable, the moderator • A significant interaction effect between the independent variable and the moderator variable is evidence of a moderator effect

Moderators B moderates the relationship between A and C B1: A C B2: A C

Why Assess Interactions (Moderators)? • Researchers often simply compare ethnic groups on risk of outcome relative to whites, controlling for covariates (e.g. age, SES, risk factors) and provide odds ratios of outcome relative to whites • focus is on direct (main) effects only • Example: What is the effect of ethnicity on CVD risk, controlling for other covariates including smoking?

Why Assess Interactions? (cont.) • Does not address mechanisms by which the groups might differ on the risk of outcome. • By testing interaction terms (moderator effects), can assess if relative importance of a risk factor is the same (or differs) by ethnic group • Example: Are the effects of cigarette smoking on CVD risk the same for African Americans compared to whites? • Assess ethnicity x smoking interaction term

Testing for Interaction (Moderator) Effects Using Regression Approach • Regression approach:A (predictor) and B (moderator) are entered first (main effects) followed by the interaction term A x B (interaction effects) • Example:Enter ethnicity and smoking followed by ethnicity x smoking interaction term • If interaction is significant, effect of smoking on CVD risk differs across ethnic groups

Testing for Interaction (Moderator) Effects • Plot regression lines and assess significance of interaction term African Americans Risk of CVD Whites Cigarettes/day

Example: Job Strain Model Moderation: Effects of stress on smoking (or CVD) depends on race, level of social support and decision making authority Mediation: Part of the effects of perceived stress on CVD are explained by level of smoking Modifying Factors Individual Social Environmental (race, age) (social support) (latitude to make decisions) Long-term health (cardiovascular health) Short term response (smoking) Perceived stress

Types of Diverse Groups • Health disparities research focuses on: • Minority vs. non-minority • Low income vs. others • Low education vs. others • Limited English skills vs. others • Vulnerable vs. non-vulnerable

Diverse Groups Underrepresented in Research • Racial/ethnic minorities, older persons, and low SES groups underrepresented • Little or no information on treatment effectiveness or pathways to health in diverse groups • e.g., little research on moderator effects - are treatments equally effective across ethnic groups? • Most research findings may not generalize to the underrepresented groups

Health Research Beginning to Include Minority and Other Diverse Groups • New focus on research to understand and reduce health disparities • conduct epidemiological studies of determinants of health disparities • examine treatment disparities • compare treatment effectiveness across ethnic groups • intervene to reduce health disparities

Measurement Implications • Most health-related concepts and measures were developed in mainstream population groups (white, middle class) • Subgroup analysis of measures (e.g., by ethnicity) has been rare • Question: Are existing measures relevant, appropriate, reliable, and valid in these other groups? • Very little research or published information on measurement qualities in diverse groups

Conceptual Frameworks of Health and Introduction to Conceptual Issues in Diverse Populations