3. Burden of disease

Question 1

What is the definition of life expectancy?

Answer 1

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

Question 2

How to calculate Life Expectancy?

Answer 2

Total no of person years lived above age x / no surviving to age x

Question 3

What does a cause elimination life table do?

Answer 3

Estimate what the life expectancy would be if a specific cause of death would be eliminated

Question 4

What is a cause elimination table used for?

Answer 4

● 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

Question 5

Mention 4 different aspects of LE vs YLL

Answer 5

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

Question 6

YLL needs an ideal, bc..

Answer 6

expects you know how long a person who dies would have lived

Question 7

Mention 4 points of EYLL (expected YLL) vs 1 point PYLL (potential YLL)

Answer 7

EYLL:

1. 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

Question 8

What are common aspects of LE & YLL?

Answer 8

• 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)

Question 9

What is the difference between healthy life expectancy (HLE) vs Health Adjusted Life Expectancy (HALE)?

Answer 9

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)

Question 10

What is DALY? How is it measured?

Answer 10

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

Question 11

How to calculate YLL for a group?

Answer 11

YLL = N x L (no of deaths x average no of years of life lost)

Question 12

How to calculate YLD (Years lived with disability)?

Answer 12

I x L x DW
= Incident cases x average duration of case x disability weight.
Take into account combined weight!

Question 13

How do DW’s work (disability weights) for DALY and HALY?

Answer 13

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.

Question 14

How is this disability weight valued?

Answer 14

by
● Experts (doctors)
● Patients - not preferred: risk of underestimating own disability
● General public

Question 15

Name some examples for valuating disability weight

Answer 15

1. Visual analogue scale (VAS): rating on a scale of 1 to 100
2. 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?
3. 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?

Question 16

What is essential data to calculate DALY’s?

Answer 16

• 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)

Question 17

What does GBD (global burden of disease) do? What is it measured in?

Answer 17

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

Question 18

What were 3 major objectives for GBD?

Answer 18

1. Inclusion of non-fatal health outcomes
2. Independent, objective evaluations
3. Measure comparable to that used in cost-effectiveness (QALY: Quality Adjusted Life Years)

Question 19

What are messages from GBD?

Answer 19

• 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!)

Question 20

What is an ecological study?

Answer 20

Study type that compares different populations, you use data that already exists from a group. You do not measure individual things

Question 21

What is QALY?

Answer 21

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.