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UNDERSTANDING CAUSATION AND ACTING ON HEALTH

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Relationship between environment and lifestyle (Hippocrates) ... Life cycle - perinatal, misadventure, chronic disease, senescence ... – PowerPoint PPT presentation

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Title: UNDERSTANDING CAUSATION AND ACTING ON HEALTH


1
UNDERSTANDING CAUSATION AND ACTING ON HEALTH
  • Vivian Lin
  • PHE61AIS

2
OVERVIEW
  • Evolution of models of causation the challenge
    of chronic, non-communicable disease
  • Relationship between models of causation and
    models of intervention
  • Contesting the notion of intervention

3
KEY MESSAGE
  • Chronic non-communicable disease epidemiology
    challenges thinking about causation
  • Single interventions no longer useful
  • Models of causation matter
  • Models of intervention contested

4
WHAT CAUSES ILL-HEALTH?
  • Relationship between environment and lifestyle
    (Hippocrates)
  • Sinful behavior and punishment for transgression
    against God (19th Century)
  • Miasma - malodorous and poisonous particles
    (Broad Street pump)
  • Contagion (14th Century germ theory)
  • Multiple causation (multifactorial etiology)

5
HENLE-KOCH RULES FOR DETERMINING CAUSATION
  • Organism present in every case of the disease
    (and in no other disease)
  • Organism able to be isolated and grown in pure
    culture
  • Organism must, when inoculated into susceptible
    animal, cause the specific disease
  • Organism must be recovered from the animal and
    identified

6
SIMPLE CAUSATION vs ECOLOGICAL MODEL
7
NOTIONS OF PREVENTION
  • Primary to ensure disease does not occur
  • (Primordial vs primary acting at environmental
    vs individual levels)
  • Secondary early detection (and early treatment)
  • Tertiary early return to health

8
MCKEOWN THESIS
  • Conditions determined at fertilisation (genetic
    diseases) vs conditions occurring in appropriate
    environment (prenatal and post-natal)
  • Long historical view - 1) nomadic (food and
    violence as limiting factors), 2) agricultural
    (fluctuating food supply), 3) transitional
    (nutritional improvement and hygiene), 4)
    industrial (air/water/food-borne down, infant
    mortality down)
  • Key determinants - nutrition and hygiene

9
CRITIQUE OF THE TRIAD
  • Web of causation - diseases never depend on
    single isolated causes complex of antecedents
    create conditions necessary (chains of causation)
  • Health field concept - health/illness depends on
    interaction between human biology, environment,
    lifestyle, and health care organisation

10
APPLYING THE HEALTH FIELD
  • Biology - genes, circadian rhythms, immune status
  • Lifestyle - diet, physical activity, tobacco,
    drug and alcohol, sexual behavior
  • Environment - microbes, pollutants, housing and
    crowding, stressful events, mobility, social
    class
  • Health services - preventive services, treatment,
    rehabilitation

11
CAUSATIVE FACTORS
  • Precipitating or proximate factors - necessary,
    specific, immediate, principal agent
  • Contributory factor
  • - predisposing (age, sex, previous illness)
  • - enabling (low income, poor nutrition,
    inadequate health care)
  • - reinforcing (repeated exposure)
  • Risk factors are positive associations but not
    necessarily sufficient to cause the disease

12
INTERVENTIONS BY FUNCTION AND TARGET GROUP
13
CHRONIC DISEASE RISK FACTORS
  • Smoking
  • Nutrition
  • Alcohol
  • Physical Activity
  • Stress
  • Medication use

14
INTERVENTION IMPLICATIONS?
  • What to act upon in order to improve health? Does
    traditional notion of primary, secondary and
    tertiary prevention still hold?
  • Traditional pathways to health - access to health
    care (insurance), health protection (healthy and
    safe environment), health education (individual
    knowledge and skills)
  • What additional actions are required? (policies,
    services, individual knowledge and skills)

15
Barriers to initiating behaviour change
16
Barriers to maintenance of behaviour change
17
Behaviour Change Models
  • Social cognition models assume that an individual
    evaluates the costs and benefits of a health
    action and that this evaluation is determined by
    attitudes, social norms, self-efficacy etc.
  • Health Belief Model
  • Theory of Planned Behaviour
  • Stage Models assume that people can be classified
    according to a discrete stage of change
  • Transtheoretical Model
  • Increasing perceived control or self-efficacy are
    cornerstones of most behaviour change models

18
Transtheoretical Model (Prochaska DiClemente
(1984)
  • Four tenets
  • People move through stages of change
  • Ten processes of change identified to assist
    change
  • Decisional balance positive aspects of behaviour
    need to outweigh negative aspects
  • Self efficacy (confidence) needs to increase to
    maintain behaviour change

19
Stages of Change
  • Pre-contemplation No plan to engage in
    behaviour, decisional balance negative
  • Contemplation Considering engaging in behaviour,
    decisional balance negative
  • Preparation Active preparation to engage in
    behaviour
  • Action Behaviour adopted, decisional balance
    positive
  • Maintenance Behaviour maintained for at least 6
    months, decisional balance positive

20
RECOGNISING COMPLEXITY AND INTERACTIONS
  • Health status includes disease, function and
    well-being
  • Environmental factors act and interact in diverse
    ways
  • Health services is a consequence of health status
    as well as determinant (positive and negative)
  • Biological and behavioral responses can be
    protective as well as risky

21
WHY WORRY ABOUT DETERMINANTS - RESEARCH?
  • Is our knowledge/evidence base sufficient for
    action?
  • What is the pathway/relationship between various
    determinants (social, environmental and
    biological)?
  • Which risk factor is most amenable to action, and
    by what action?
  • What actions are effective, and for whom?

22
KEY DESCRIPTIVE STUDIES
  • 1950s - Framingham study - cohort study on heart
    disease
  • 1960s Kitagawa and Hauser mortality and SES
  • 1960s - MRFIT - Multiple Risk Factor Intervention
    Trials - intervention in clinical setting
  • 1970s - Alameda County Population Health
    Laboratory North Carolina migration Japanese
    migrants - social epidemiology

23
MORTALITY RATES in UK (Black Report, 1971)
Rate per 1000
24
MORTALITY in ENGLAND (1993-95)
Rate per 100 000
25
HEALTH BEHAVIORS in US Alameda County Study
1965-1974
26
CONTRIBUTION OF LIFESTYLE FACTORS (Whitehall CHD
mortality 25-year follow-up)
Whitehall I - 1967-1992
27
OVERALL EVIDENCE
  • Health increases along a gradient as affluence
    increases
  • Health inequalities found in all developed
    countries, at national/regional/local levels, for
    all diseases and causes of death, for men and
    women, across the whole age range
  • Differences in lifestyle explain up to half of
    the difference
  • Health gap between rich and poor not decreasing

28
WHY ARE SOME PEOPLE HEALTHIER?
  • Life cycle - perinatal, misadventure, chronic
    disease, senescence
  • Population characteristics - gender, SES,
    ethnicity/migration, geography/place
  • Other explanations - lifestyle, physical
    environment, social environment, reverse
    causality, differential susceptibility,
    differential access to health care

29
KEY INTERVENTIONAL STUDIES
  • 1970s - North Karelia Stanford Minnesota
    Pawtucket - community-based prevention
    interventions
  • 1980s - 1990s - Richmond Smoking Cessation
    Program Wellness Guide

30
KEY FINDINGS
  • Identification of key risk factors - smoking,
    high blood pressure, cholesterol
  • Intervention effectiveness limited - no magic
    bullet
  • Socioeconomic differential (or gradient) in
    mortality, in risk factors, and in intervention
    effectiveness
  • Gradient applicable to other NCDs and health
    outcomes

31
1990s DEVELOPMENTS
  • Whitehall Study sense of control
  • Barker hypothesis and life course approach
  • Kaplan, Lynch - childhood SES as predictor
  • Wilkinson - relative income inequality
  • Karasek, Thorell - job stress
  • Krieger - racial discrimination
  • McIntyre - structural opportunities

32
SOCIAL DETERMINANTS
  • Socioeconomic status
  • Stress
  • Early life
  • Social isolation or exclusion
  • Nature of work
  • Unemployment
  • Social support
  • Addiction
  • Availability of good food
  • Transportation system

33
PHYSIOLOGICAL EXPLANATIONS
  • 1. Psychosocial stressors (life events)
    vulnerability factors (personality supports)
  • 2. Psychobiological stress responses
  • a) neuroendocrine (insulin, testosterone),
  • b) metabolic (cardiovascular, gastrointestinal,
    renal),
  • c) immunological (white cell counts)
  • 3. Disease states

34
PSYCHOSOCIAL EXPLANATION
35
NEO-MATERIALIST EXPLANATION
36
MATERIAL AND PSYCHOSOCIAL FACTORS
37
LIFE COURSE APPROACH
38
OTTAWA CHARTER FOR HEALTH PROMOTION
  • Healthy public policy
  • Supportive environment
  • Community action
  • Individual skills
  • Health services

39
PUBLIC HEALTHMEDICINE PARTNERSHIP - LOCUS OF
RESPONSIBILITY FOR PREVENTION
40
COMMUNITY-ORIENTED PRIMARY CARE
  • IDEAL FEATURES
  • Population - identified community
  • Governance - allow community involvement
  • Information - facilitate planning and evaluation
  • Funding - incentives for cost-effective services
  • Workforce - team-based, combine public health and
    clinical medicine skills
  • Service - comprehensive, coordinated, consumer
    focused
  • CONCEPT
  • Use epidemiological and clinical skills
  • Address determinants and consequences of health
    and illness
  • Concern with environment/ family/ individual
    with health services and behaviours

41
EXAMPLES OF COPC/PHC
  • Neighborhood health centres in US
  • Community health movement in Australia
    Aboriginal Medical Services, Womens Health
    Centres, Workers Health Centres, Community Health
    Centres
  • ?Polyclinics in Cuba
  • ?Barefoot doctors in China

42
Levels of change
Organisational level change
Group/team level change
Organisational Context
Personal level change
43
Some change processes
Lewin (1951)
Changing
Relearning
Unlearning
CONTINUAL FEEDBACK
Institutionalising
  • Awareness
  • Identification
  • Implementation
  • Institutionalisation
  • Establish sense of urgency
  • Create guiding coalition
  • Develop vision strategy
  • Communicate the change vision
  • Empower broad-based action
  • Generate short-term wins
  • Consolidate gains
  • Anchor in the culture (Kotter)

44
Characteristics of successful change programs
  • Clear objectives
  • Full information
  • Appropriate strategies
  • Good timing
  • Participation from staff
  • Support from key power groups
  • Using the existing power structures
  • Critical assessment beforehand
  • Building majority support
  • Continuing evaluation
  • Adequate reward

45
INTERVENTIONS OR PATHWAYS?
  • Interventions focus on specific risk factors
    and interrupt causal chains?
  • Social epidemiology focus on clustering of risk
    factors in populations, non-specific mortality,
    or stability in distribution of health problems
  • Primary health care and health promotion
    movements focus on individuals and groups
    taking control over the conditions that affect
    health (through personal and political action)

46
MODELS COMPARED
47
IS CONTESTATION NECESSARY?
  • Determinants risk and protective
    factors/conditions, lifestyles/ environment
  • Pathways/interventions health/non-health
    sector, individual or community or system level,
    personal or political
  • Who acts provider or consumer
  • Which group leads medicine or public health
  • How is action taken individual or in partnership
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