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