Lecture 10. Public Health 1: Definitions and Measures Flashcards
What is demography?
The study of populations
What is population size dependent on?
Birth, death, immigration and emigration
How is the information required to enumerate the population collected?
Through registrations and census
What is epidemiology?
The branch of medical science concerned with the incidence and distribution of disease
What is epidemiology a branch of?
Ecology
What is public health?
Improving the health of the population (can be whole population or subdivided into subpopulations)
What does improving the health of the population mean?
Rather than treating the diseases of individual patients (that’s medicine not public health)
We must know the “health of the population”
Interventions to improve the “health of the population”
What is the easiest way to measure public health?
Deaths (mortality)
Unambiguous; easily counted
“Healthy people don’t die”
Is final – there is no prevalence of death, only incidence
What was one of the first examples of public health related measurements of death by cause?
Florence Nightingale recording deaths in the Crimean War
What are ICD-10 codes?
Origins in 1850s and managed by WHO
Codes change over time (C62 = AIDS)
These are y clinical diagnosis, not by “cause”
How many people die in the UK each year?
~550,000
What are ~80% of deaths in >54 year olds due to?
Circulatory, respiratory and neoplasm
What are ~60% of deaths in the 15-24 year old age group olds due to?
External factors
Accidents, self-harm, assaults (codes V01-Y89)
What do deaths before age at the “expected” death result in?
Loss of life years
How is public health improved?
When the number of life-years is increased
What does life-years gained (LYG) mean?
If 1000 people live a year longer than expected then it’s 1000 LYG
What does potential years of life-lost (PYLL) mean?
How many life years does a disease take away from a population
What do mortality measures assume?
That all life-years are equal (saving one year of life of an 80 year old is the same as a 5 year old)
Doesn’t account for age at which they lived or disability etc
What are the current UK life expectancies at birth?
Male: 77 yrs
Female: 82 yrs
When can life expectancy be calculated?
At any age
What are responsible for great losses of healthy life?
Many diseases such as paralysis and chronic depression
Common and long-lasting demands on healthcare
What does QALY mean?
Quality adjusted-life year - usually gain of life-years
What does QALY mean?
Relative measure of the future stream of disability-free life lost as a result of death, disease & injury
If you expect to live for 23 years and remain in perfect health, how many DALYs are lost?
23 DALYs (same as LYG)
If you expect to live for 23 years but become blind where a year of life is valued at 0.6 (ie 60% of a healthy life), how many DALYs are lost?
23*0.4 = 9.2 DALYs
What does disability weighting measure?
Prevalence rather than incidence
What can disability weights be?
Culturally specific (better to be blind in the devloped world than the less developed)
Negative
What is important to consider when discussing disability weighting?
Disability weights are open to some interpretation, and different approaches are continually being developed
What does the EQ-5D score measure?
Level of independence of a person (can you get out of bed on your own, can you cook etc)
What is one of the biggest problems when it comes to disability weighting?
Children are not accounted for (have extremely low EQ-5D) so most graphs start at around 20
What do certain cultures account or which the UK does not?
Age weighting
Some cultures value those who’ve lived longer lives less “fair-innings’
In the UK all ages are valued equally
What is time preferencing?
Discounting - the value of a life decreases into the future
Might swap five years of health in the future for one healthy year now
What do DALYs enable use to examine?
Enables “burden of disease” to be measured
Enables cost-effectiveness analyses
See the impact on the healthcare industry
How many PYLL per year in the UK?
~3 million
~6 years per death (people dying early due to various diseases and such)
The rank order of cause is similar to death apart from what?
External causes
Deaths that happen younger have greater impact
How many DALys are lost annually in the UK?
~7.8 million
Although ischaemic heart disease remains at the top, why are neuropsychiatric disorders ranked above neoplasms?
Neuropsychiatric disorders are a much greater burden than neoplasms
Mental issues will probably top cardiovascular in the future
How much money from the government is given to “public health”
Unknown, however public health includes elements of all aspects of government spending
Given limited resources, how do we decide between interventions?
Choice between saving 1 life or 5 lives at the same “cost”, choose 5 lives
Otherwise, no basis for choosing when a choice must be made
Requires that we measure the effects of costs
What is cost-effectiveness?
Division of health benefit
Interventions (e.g. immunisation, chemotherapy, intensive care wards) buy DALYs
Choose those interventions that buy the most health (LYG per £ or DALY per £)
The only way of rationally deciding between interventions when resources are finite
What is NICE?
UK National Institute of Health and Clinical Excellence (created to avoid politically difficult decisions)
Creates clinical guidelines (e.g. which drugs should be prescribed, which treatments should be used)
Uses combination of effectiveness (e.g clinical trials) and cost
What does NICE not account for?
No age weighting; discounts both outcomes & costs
No account of “total cost”
An intervention that costs less than £X to save a DALY is considered cost effective
How much money is each DALY currently?
~£20,000-30,000 paid by the government to keep a person healthy for a year
Why is there tension between the DoH/NHS and the pharmaceutical industry?
UK trying to set price limits on drugs – Pharmaceutical industry trying to break the limits
What other roles does NICE have?
Public health – Increasingly used for public health decision-making (read *)
Value-based pricing – NICE now has a central role in determining the value of a drug/intervention and therefore the
price that the NHS will pay
Social care – NICE’s role has expanded to include developing guidance and quality standards for adults and children’s services
Trying to expand into all areas that impact an individual’s health
What are examples of public health interventions?
Eduction - empowerment
Mass screening/testing - immunisation; breast cancer; helminths
Diet - Micronutrient supplementation (school milk)
Fertility - contraception; maternal health
Drugs - tobacco, alcohol, illegal
Water/sanitation
Pollution
When talking about maximising the health of a population, do we talk about morbidity or death?
Morbidity
