Module 4: Deciding on Interventions to Improve PopHlth Flashcards
Population/public health goal
Provide max benefit for largest no of people
Why worry about priorities
Health rss are limited
Each prioritisation has an opportunity cost
Rationing involves ethical and evidence-based judgement
Difficult to compare outcome ‘apples and oranges’
Individual (clinical services) vs pop needs (pop health services)
Reasons for Global Burden of Disease (GBD) project
Data on burden of disease and injury from many countries were incomplete
Available data largely focused on deaths; little info on non-fatal outcomes (disability)
Lobby groups can give distorted images of which problems are most important
Unless the same approach is used to estimate burden of diff conditions, it’s difficult to decide which conditions are most important
Aims of GDP project
To use a systematic approach to summarise the burden of diseases and injury at pop level, based on epidemiological principles and best available evidence
- aids in setting health service and research priorities
- aids in identifying disadvantaged groups and targeting of health interventions
To take account of deaths as well as disability when estimating burden of disease
Disability Adjusted Life Years (DALYs)
Specific measure developed to achieve aims of GBD project
A summary measure of pop health combining data on premature mortality and non-fatal health outcomes to represent health of a particular pop as a single number
DALY = ?
YLD + YLL
YLD = years lived with disability
YLL = years of life lost
DALY values
A year in perfect health = 0
A year of life lost due to death = 1
A year with disability = between 0 and 1
YLL (Years of Life Lost)
Represents mortality by counting the years lost due to premature death caused by a disease
i.e. the years lost if a person dies before reaching average life expectancy in their country
YLL = no of deaths from disease in a year x years lost per death relative to an ‘ideal’ age
YLD (Years Lived with Disability)
Represents morbidity by counting years lived with disease
No. of cases with non-fatal outcome with the disease
Average duration of non-fatal outcome until recovery/death
Disability weight (represents severity of impairment)
A DALY represents…
A lost healthy life year
DALYs enable comparisons between…
Diseases by using one measurement unit that compares premature death and disability
Between diseases to:
- prioritise health interventions
- monitor health interventions
- assess changes of disease burden over time
In general, as countries developed economically…
Average life expectancy has increased and fertility rate has decreased
GBD groups
Group 1: Communicable/infectious diseases - includes communicable diseases and perinatal conditions (early life)
Group 2: Non-communicable diseases (NCDs) / chronic diseases
Group 3: Injury
Major gains of DALY approach in informing priority setting globally
Drew attention to previously hidden burden of mental health problems and injuries as major public health problems
Recognises non-communicable diseases as a major and increasing problem in low and mid-income countries (not just rich countries)
DALYs: Challenges - questions to ask
Who should decide what weights should be assigned to various disabilities?
Is it reasonable to apply one set of disability weights globally? Do all people with a particular level of ‘disability’ have similar opportunities to be part of society?
How does physical and social environments influence disability experiences?
2 major challenges in using DALYs to quantify burden of ‘disability’
Disability weights are considered to be the same as the severity of an impairment relating to a disease/health condition, and don’t vary with a person’s social position, where they live, access to healthcare etc.
GBD project criticised for its potential to represent people with disabilities as a ‘burden’
Issues highlight differences in the way ‘disability’ as a concept is sometimes viewed - perceptions
Models of disability
Medical model
Social model
Medical model of disability
Disabled people are defined by their medical condition
Regards disability as an individual problem
Promotes view of a disabled person as dependent and needing to be cured or cared for - excluded from society
Control resides firmly with professionals
Choices for individual are limited to options provided and approved by the ‘helping’ expert
Social model of disability
Disability is no longer seen as an individual problem but as a social issue caused by policies, practices, attitudes and/or the environment
Focuses on ridding society of barriers, rather than relying on ‘curing’ people who have impairments
A higher burden of deaths at a younger age in low income countries contribute…
A lot of YLLs to the global DALY burden
Diff countries use diff measures to prioritise health issues, which leads to…
Difficulty prioritising on a global scale
High vs low income countries - groups of disease
High income - high amount of group 2 (non-communicable) disease
Low income - high amount of group 1 (communicable) disease
Disability weight - legislation
Can diff countries be given the same disability weight?
Which health model is GDP perceived to focus more on
Medical model of disability
Causes vs risks
Cause - the reason for death/disability (outcome); determinant
Risk - the reason for cause; determinant of determinant
Epidemiological transition
Characteristic shift in common causes of death and disability from perinatal and communicable (infectious) diseases to non-communicable (chronic) diseases
Causes of burden of disease in DALYs overtime
Over time, NCD risks increase and risk for communicable diseases decrease - known as risk transition
Key factors influencing the risk burden
How strong the ‘causal’ association is between risk factors and health conditions (e.g. RR)
How common the exposure to this risk is in the pop of interest (e.g. prevalence of risk factor in pop)
To identify the leading risk factors, GBD examined…
PAR - The amount of ‘extra’ disease burden attributable to a particular risk factor in a pop
This is the amount of disease burden we could theoretically prevent if we removed that risk factor from that pop
Low to high income countries - risks
Low: predominantly communicable and perinatal disease risks
Mid: NCD risks start to predominate
High: predominantly NCD risks
Known as risk transition
Low to high income countries - diseases
Low: slight decrease, but still predominantly communicable diseases
Low-mid: large decrease, but still slightly predominantly communicable disease
Mid: pattern shifted, from more communicable to much more NCDs
High: stable for some time - NCDs predominant
Low to high income countries - risk factors contributing to GBD by SESof country
Increasing SES of country = increasing risks for NCDs and decreasing risks for communicable and perinatal communicable diseases
Risk transition
Changes in risk factor profiles as countries shift from low to higher income countries, where common risks for communicable and perinatal diseases (e.g. unhygienic water) are replaced by risks for non-communicable diseases (e.g. tobacco)
Middle-income countries - risks
In many middle-income countries, previously common risks for communicable diseases co-exist with increasing risks for non-communicable diseases
These countries face a ‘double burden of disease’
Major challenges for health policy
Which countries affect NCDs
> 80% of NCDs contributing to global burden of disease is from low and mid-income countries
NCDs - concentration
Concentrated among poor
Double-burden requires…
Double response
NCDs - affect which age group?
Almost half in 30-69 year olds
Prevention of chronic diseases
They can be prevented; significant proportions of premature heart disease, strokes, cancer and diabetes can be prevented
Population groups most affected by NCDs
Low income groups
Those living in LMICs
Determinants and determinants of determinants of NCDs
Underlying socioeconomic, cultural, political and environmental determinants –>
Common modifiable and non-modifiable risk factors –>
Intermediate risk factors –>
Main chronic diseases
Unequal NCD epidemic - commercial sector
Commercial sector (distal/upstream determinant) drives the NCD epidemic Creates uneven distribution of risks --> unequal distribution of disease and health inequities
How have commercially driven epidemics come to be - smoking
Social norms changed as smoking became popular among other social groups - smoking in 1960s was seen as a status symbol, promoted by the rich
Commercial sector drives NCD inequities by…
Marketing to vulnerable targets, shaping preferences and changing social norms
Changing physical and social environments
- influence public policy development
- concentrate outlets in low SES areas
Actively exploit difficulties with behaviour change
- frame education as the most effective solution (social responsibility)
- offer choice and pleasure
- emphasises moderation
Density of outlets
Not randomly distributed - more gaming machines, liquor outlets and takeaways for populations per unit in most deprived areas
Industrial epidemics
Diseases arising from over-consumption of unhealthy commercial products
Addressing commercial determinants NCDs and health inequalities
Shift focus from individual behaviours to broader environment and upstream drivers of unhealthy product consumption
Tackle broader determinants of health (upstream/distal determinants)
Develop effective health policy recognising tension between commercial and health objectives
Tobacco control strategies (WHO)
MPOWER
Monitor tobacco use and prevention policies
Protect people from tobacco use (smoke-free legislations)
Offer help to quit tobacco use (downstream) - targeted programmes
Warn about dangers of tobacco
Enforce bans on tobacco advertising and sponsorship
Raise taxes on tobacco
Right to Help concept
Respect - to be free from discrimination
Protect - protect pop from 3rd party interference
Fulfill - fulfill right to health and address inequalities
Uses of epidemiology in obesity
Descriptive - current trends and burden
Predictive - future burden
Explanatory - changes over time, differences between pops
Evaluative - effectiveness of interventions
Global trend of obesity
Over time, all age groups increased simultaneously and equivalently
Increasing obesity at diff rates in diff regions of the world
NZ - obesity rank
Adults - third fattest in OECD
Children - third fattest on OECD
Increasing trend
NZ obesity - SES quintile
Increasing trends by lower SES
Gradient much steeper for children than adults
Most overweights and obesity in least disadvantaged group is overweight (less obesity) –> less severe
More severe obesity in most deprived
NZ obesity - ethnicity
> 60% of Pacific children overweight/obese and half of those are obese
2 main factors/causes of obesity (by DALYs)
Diet (poor nutrition) - biggest problem in many countries
High BMI
Consequences of obesity
Metabolic diseases (type 2 diabetes, CVD, most cancers) Mechanical disorders (arthritis, back pain, skin disorders) Psychological problems (low self esteem, reduced quality of life) Social consequences (weight bias and discrimination)
Type 2 diabetes vs BMI
Increasing risk of getting diabetes for increasing BMI
To get rid of diabetes, must get rid of obesity
Causes of obesity
Individual questions - why am I getting fatter?
Pop questions - why is this pop’s obesity prevalence going up?
Answers depend on the question - genetic, metabolic, behavioural, environmental
Obesogenic environments
The sum of influences the surroundings, opportunities or conditions of life have on promoting obesity in individuals or pops
Environment type: Physical, economic, policy, socio-cultural
Micro-environment (settings): Food, physical activity
Macro-environment (sectors): Food, physical activity
Obesogenic environments - environment type
Physical - what is or isn’t available?
Economic - what are the financial factors
Policy - what are the rules?
Socio-cultural - what are the attitudes, beliefs, perceptions and values?
Escalating obesity pandemic - factors
The food system - the most plausible explanation for the simultaneous, global increase in obesity is that it has been driven by changes in global food supply (4Ps), creating pop ‘passive overconsumption’ of total energy
Other changes have contributed - e.g. reduced occupational activity
Underlying political and economic drivers
Obesity through a pop - who is affected first?
Women –> Men
Middle age –> Children
High SES –> Low SES
Urban –> Rural
Local environments shaping obesity prevalence
Economic environments - income (disparities)
Physical environments - food, physical activity
Socio-cultural environments - food, physical activity, body size
Policy environments - market regulations
Population differences in obesity prevalence
Obesity prevalence is driven up by global drivers but diff local environments determine the trajectories of diff pops
Moderators attenuate or accentuate rise in obesity
Determinants of obesity
Drivers (changes over time drive changes in outcomes over time) –>
Mediators (factors through which the drivers operate) –>
Outcomes (changes in obesity prevalence)
Moderators (factors which accentuate or attenuate trends) –>
Mediators
Obesity - now
Youngest and well-off children starting to turn the corner
For NZ - may be starting to go down
Policy inertia on implementing food policies
Food industry opposition:
- direct opposition (Coca Cola on SSB taxes)
- self-regularly pledges
Government reluctance to regulate/tax:
- weak governance systems, conflicts of interest
- belief in education approaches and market solutions
- unwilling to battle food industry (chill effect)
Lack of sufficient public demand for policies:
- usually supportive of policy actions
- not translated into pressure for change
Obesity prevention action in NZ
Major policies:
- junk food marketing to children; no regulations
- tax on sugary drinks; none
- healthy food policies in schools; voluntary
- healthy food policies in early childhood settings; poorly implemented
- front of pack labelling; only 20% implemented
- restrictions on health claims on foods; yes
Community action:
- Healthy Families NZ
Obesity - history to now
1980s - scientists identifying epidemic
1990s - advocacy to get obesity on public and political agenda
2000s - increased awareness and some action; largely program-based
2010s - evidence of effectiveness of interventions strengthening, and declines in some pops, ongoing battles over food policies
HIV - DALYs
Ranked 11th in both 1990 and 2016
HIV - demand from public health epidemiologists
Human rights (Varying perspectives) and fears (local situation)
Screening (in absence of a known agent and test)
Request for ‘definitive’ evidence
Costs for screening vs numbers to save
HIV: What was known at the time?
Transmission form:
Infected blood (transfusions)
Homosexual men
No specific test but Hepatitis test was an indicator (proxy) Virus was not isolated at the time Vaccine not available Treatment options minimal Prevention - best hope
HIV: What we know now
Several modes of transmission identified - facilitate prevention
Cheap, reliable and HIV-specific screening tests available
Caused by a virus (human immunodeficiency virus)
Better treatment options - improved life-expectancy
Vaccine still not available
Global summary of HIV/AIDS epidemic (2016)
No of people living with HIV: 36.9 million
People newly infected: 1.8 million
No of HIV-related deaths: 1 million
> 70% of infected people live in Sub-Saharan Africa
Global summary of HIV/AIDS epidemic - no of people accessing antiretroviral therapy (ARV)
20.9 million (June 2017)
AIDs epidemic: low access to treatment
Especially marked in low and middle-income countries
78% treated in Western and central Europe and North America
36% treated in Western and central Africa
Changes in life-expectancy at birth in selected countries in Africa 1985-2015
Dramatic decrease in life-expectancy in 1990s e.g. Zimbabwe
Dramatic increase in life-expectancy in 2000s due to increased availability and accessibility of treatment
Communicable disease effect on life-expectancy
Communicable diseases can have a profound effect on life-expectancy, particularly in low and middle-income countries
No of people living with HIV
Increases, due to life-prolonging treatment
Decreased no of people newly infected - preventative measures
Decreased no of deaths –> increased prevalence pool
AIDs epidemic - global factors shaping the epidemic
AIDs related deaths are decreasing and people are living longer with HIV due to improved treatment and access to treatment/care
Nearly 50% of people with HIV don’t know their HIV status
Most people living with or at risk for HIV don’t have access to HIV prevention, treatment and care
AIDS epidemic - different regions / populations
Affected differently
Sub-Saharan Africa has ~1.2 million new infections per year
Young people account for a significant and rapidly growing % of pop and are reaching age of highest risk for sexual transmission
To reduce burden of HIV/AIDS, it is essential to…
Tailor the response and interventions to local circumstances and prevalent risk factors
HIV - high risk groups
Homosexuals (men)
Heterosexuals
Sex workers
Injecting drug users
Those receiving injections with un-sterilised needles
Infants born to or breast fed by untreated HIV+ mothers
Anyone receiving unscreened blood products / organs
HIV - transmission modes
Unprotected sexual intercourse with HIV+ person
Sharing unsterilised injections and needles
Mother-to-child transmission
Blood-borne