Transcript Document

Basic Concepts in
Individual and Population Health (3)
Intervening on Skin Cancer:
a Population Approach
Ian McDowell, Paula Stewart
December 2, 2008
Road map of ideas
Foundations
Intro Unit:
Health disparities;
Determinants;
Physician roles
Prevention
Public
health
Today
Evaluation
(RCTs)
Epidemiololgy
& statistical
methods
Scholar;
Individual vs.
population
approaches
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Health
promotion
Health
Advocate
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Case scenario
Solar Sally presents with a
suspicious skin lesion on her
scalp that troubles her
mainly because “it looks so
gross”
• She is a healthy sportswoman who plays “beach”.
• Is vague about her use of sunscreen; hats interfere
with her volleyball.
• She’s in some denial and seems disconnected
from concerns over sun exposure.
• Referral to dermatologist leads to diagnosis of
melanoma.
•Your options: treat; preach protection; bemoan the
foolishness of youth...?
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Physician Roles : Options for cancer
broad
focused
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•
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Health promotion & population health
Primary prevention
Secondary prevention (screening)
Supportive services – home,
community
• Treatment – self-care, education, meds,
surgery etc.
• Rehabilitation
• Palliation
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Health Promotion
“A process of enabling people to increase control over,
and to improve, their health” (WHO)
Ottawa Health Promotion Charter (WHO, 1986)
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•
•
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Develop personal knowledge and skills
Create supportive environments
Strengthen community action
Build healthy public policy
Reorient health services
During the 1990s, there was a move from
Health Promotion to Population Health
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Definitions of Population Health
• John Frank, 1995: "Population health is a conceptual
framework for thinking about why some people, and some
peoples, are healthier than others - the determinants of health
at individual and population levels. . .”
• Health Canada, 1994: "Population health strategies address
the entire range of individual and collective factors that
determine health, while traditional health care focuses on risks
and clinical factors related to particular diseases. Population
health strategies are designed to affect the entire population,
while health care normally deals with individuals one at a
time, usually individuals who already have a health problem
or are at significant risk of developing one. . ."
Principles of a
Population Health Approach
Move upstream from the individual patient; consider the
context of the condition
• Consider all factors (immediate causes & underlying
determinants)
• How many people have the problem?
• Focus on prevention as well as case management
• Use multiple strategies
• Involve community in planning programs
• Allocate resources on rational basis
• Base policies on evidence of effectiveness
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Rationale for Population Interventions
• Moral arguments:
• Duty of society to protect its citizens (public health)
• A just society should reduce inequalities in health
• Reduce inequities (systematic differences that should
not occur)
• Economic arguments:
• Healthier workforce, more productivity
• More taxpayers, greater equity
• Reduce health care expenditures
• Political arguments:
• Stronger nation
• Healthy, happy people re-elect their politicians!
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Why should an MD care about a
population approach?
• Frustration with always fixing society’s ills: a way to
go “upstream”, beyond mere symptomatic treatment
of individual patients and tackle root causes
• It’s often an efficient use of resources: cost-effective
to tackle causes before they produce cases
• Moral imperative (“I will ensure that patient wellbeing is my main focus…”)
• May also be more efficient than focusing on severe
cases (see next slides)
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Health Advocacy for Solar Sally:
Who needs to be involved?
•
•
•
•
•
•
•
•
The individuals and her family
Health professionals
Sports leaders (coach, etc.)
School or university
Media
General community
City public health officials
Volunteer health organizations (cancer
society?)
• Business (sun screen manufacturers?)
• Government?
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This is somewhat daunting!
Does it need to be coordinated?
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International inequalities in health: survival of children to 5 years of age
(vertical axis) plotted by GNI per capita. Source: Gapminder.org
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Mortality rates, standardized by age, by income adequacy quintiles,
for men (blue) and women (pink) living in the community. Canada 1991 to 2001
1800
900
1600
800
1400
700
1200
600
1000
500
800
400
600
300
400
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200
100
0
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Poor
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Rich
0
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Poor
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3
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5
Rich
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Discussion Point:
High risk versus population approach
• For every disease, some people are at higher
risk than others
• We can often recognize such people before the
disease occurs; a family physician can readily
do this
• This “high-risk approach” makes intuitive
sense
• Are there alternative approaches?
Where Do the Deaths Occur?
Example: Serum Cholesterol & CVD Mortality
Distribution
of serum
cholesterol
in population
17%
20
8%
Percentage of all
CVD deaths
22%
mortality
risk
4%
%
10
19%
<1%
13%
0
9%
4
5
6
Serum Cholesterol (mmol/l)
7
8%
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Population changes
Example: levels of exercise in a population (red line).
To improve population health, you can either focus on encouraging exercise
among people who rarely exercise (producing the blue line)
Or work to shift whole population distribution (green line).
%
Low
Exercise level
High
Types of Preventive Interventions
• Active - individual must act to obtain
benefit
– Voluntary – need education, social norms
– supported by legislation
• Passive - no action required by
individual to obtain benefit
– Involuntary
– Implemented by policy or legislation
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Evaluation
• How do we know it works?
– Experimental designs
– Observational
• Statistical aspects will be covered in the
tutorial
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Experimental Studies:
Randomized Controlled Trials
Population
People
with the
disease
who meet
selection
criteria
Random
allocation
Intervention
(a)
group
Control
group
Statistic = difference in scores = (b-a) - (d-c)
This shows the experimental change minus the
change in the control group.
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(b)
(c)
(d)
Time1
(baseline)
Time2
(outcome)
Make measurements
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Non-random comparison studies
Population
People
with the
disease
who meet
selection
criteria
Intervention
(a)
group
Control
group
Statistic = difference in scores = (b-a) - (d-c)
This shows the experimental change minus the
change in the control group.
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(b)
(c)
(d)
Time1
(baseline)
Time2
(outcome)
Make measurements
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A Hierarchy of Quality of Evidence
Clinicians should choose therapy according to the best available
evidence. To guide you, sources of evidence may be ranked
according to their quality. There are various quality rankings;
here is one option. In descending order:
Level 1: High quality meta-analyses or systematic
reviews of RCTs; RCTs with low risk of bias
Meta-analyses, systematic reviews, or RCTs with
higher risk of bias
Level 2: High quality systematic reviews of cohort or
case-control studies
High quality cohort or case-control studies that had
low risk of confounding or bias
Level 3: Non-analytic studies (case reports, case series)
Level 4: Expert opinion
Source: Scottish Intercollegiate Guidelines Network
http://www.sign.ac.uk/guidelines/fulltext/50/annexb.html
(Tutorial Groups
will discuss design,
and evaluation of a
health promotion program)
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