3. Burden of disease Flashcards
What is the definition of life expectancy?
Average time a person is expected to live, based on the year of its birth or its current age (and other demographic factors)
▪ Not influenced by age distribution of the population
How to calculate Life Expectancy?
Total no of person years lived above age x / no surviving to age x
What does a cause elimination life table do?
Estimate what the life expectancy would be if a specific cause of death would be eliminated
What is a cause elimination table used for?
● quantification of potential effect of interventions
● quantification of the (relative) importance of a cause of death
> Disadvantage: can not add up effects of different diseases
Mention 4 different aspects of LE vs YLL
LE: Measures what is being achieved
YLL: Measures what is being lost
LE: Average expressed for one person
YLL: Expressed for the whole population
LE: No of years someone can expect to live
YLL: No of years of potential life lost if dying before a certain age
LE: General
YLL: Can be cause-specific
YLL needs an ideal, bc..
expects you know how long a person who dies would have lived
Mention 4 points of EYLL (expected YLL) vs 1 point PYLL (potential YLL)
EYLL:
- Uses population life expectany at the individual’s age of death
But.. Different countries may have different life expectancies
> changes in mortality change life expectancy
> Alternative: reference is to an ‘ideal’ life expectancy
PYLL:
1. Uses fixed age, typically 75
What are common aspects of LE & YLL?
- Attempt to represent impact of mortality on the population: death at a young age is a greater loss than death of an elderly person
- Focuses attention on conditions that kill younger people (accidents; cancers)
What is the difference between healthy life expectancy (HLE) vs Health Adjusted Life Expectancy (HALE)?
HLE: Life expectancy in good health
HALE: Life expectancy in good health, taking severity into account of unhealthy years
Healthy years + part of unhealthy years (Part = weighted with a “disability weight”)
e.g. one year with severe disability counts as half a healthy
(DALE falls between LE and HLE)
What is DALY? How is it measured?
DALY = Disability-adjusted life years. YLL (years of life lost) + YLD (years lived with disability).
It measures difference between actual situation and a health target, e.g. perfect health until the age of e.g. 80 years
How to calculate YLL for a group?
YLL = N x L (no of deaths x average no of years of life lost)
How to calculate YLD (Years lived with disability)?
I x L x DW
= Incident cases x average duration of case x disability weight.
Take into account combined weight!
How do DW’s work (disability weights) for DALY and HALY?
DALY: On a scale of 0 – 1: 0= no loss of health, 1 = death
HALY: On a scale of 0 – 1: 1= no loss of health, 0 = death
DALY, D from Death, Death likes people that die and therefore scores a point for death. H, from health, does not like this and scores 0 points.
How is this disability weight valued?
by
● Experts (doctors)
● Patients - not preferred: risk of underestimating own disability
● General public
Name some examples for valuating disability weight
- Visual analogue scale (VAS): rating on a scale of 1 to 100
- Time Trade Off (TTO): value one life-year with a specific disease. Then, offer to trade this year for a shorter period without the disease. How many years to sacrifice?
- Standard gamble: You have disease, surgery is offered with which it can be fully cured. How much risk on dying willing to take for the trade?
What is essential data to calculate DALY’s?
- General
● Demographic data (population numbers by age and sex) - Years of Life Lost (YLL)
● Epidemiological data on disease-specific mortality by age (and sex)
● Age-specific Life Expectancy (chosen norm) - Years Lived with Disability (YLD)
● Epidemiological data on prevalence of diseases (or: incidence and duration) by age (and sex)
● Health status valuations (disability weights)
What does GBD (global burden of disease) do? What is it measured in?
Burden of disease quantifies the gap between a population’s current health and an ideal situation where everyone lives to old age in full health (combines mortality and morbidity)
Measured in DALY’s
What were 3 major objectives for GBD?
- Inclusion of non-fatal health outcomes
- Independent, objective evaluations
- Measure comparable to that used in cost-effectiveness (QALY: Quality Adjusted Life Years)
What are messages from GBD?
- Leading causes of death are shifting from infectious diseases to non-communicable diseases
- Disability increases in middle- and high-income countries
- Tremendous progress in sub-Saharan Africa, but major challenges remain for millennium development goals 4, 5, and 6 (i.e. under 5 mortality, maternal mortality and spread of HIV/AIDS)
- Important risk factor transitions (smoking!)
What is an ecological study?
Study type that compares different populations, you use data that already exists from a group. You do not measure individual things
What is QALY?
cQuality-adjusted life year (QALY): Weight each year of life by the perceived quality of that life from a value of one for perfect health down to zero for death.
