Measuring Health and Disease in a Population

Question 1

Define Incidence rate

Answer 1

• Number of NEW cases in a population over a defined period of time
• A rate: Meaning must be per unit time

Question 2

Define prevalence

Answer 2

• A proportion of persons in a given population that has a particular disease at a given point of interval of time
• PROPORTION

Question 3

A disease with no cure and a long duration from onset to death will likely have a high or low prevalence?

Answer 3

• High
• No cure, so disease burden stays until death and if is chronic and does not kill quickly long time period to have disease.

Question 4

Can a prevalence study be used to make inferences about causation of disease?

Answer 4

• No, they are cross sectional, giving a good idea of extent of disease but no information on cause

Question 5

Define Life Expectancy

Answer 5

• Expected number of years that an individual will live based on standard dealth rates for their population

Question 6

Define Crude Mortality rate

Answer 6

• Mortality rate from all causes of death, without adjusting for distribution
• RATE:
  ie: x death/1000 people per year

Question 7

Define infant mortality rate

Answer 7

• Number of deaths among children under 1 reported during a given time period
• Divided by number of live births during same time
• Expressed as X death per 1000 live births per year
• Again RATE

Question 8

Define Maternal Mortality Rate

Answer 8

• Number of deaths of women during pregnancy and due to puerperal causes
• Expressed as x deaths per 100 000 live births per year
• RATE

Question 9

What is a a Standardized Mortality Ratio?

Answer 9

• The ratio of the observed (actual) number of deaths compared to the expected (predicted) number of deaths for a group
• RATIO of Observed:Expected

Question 10

Define potential years of life lost

Answer 10

• Calculated for a population using the difference between the actual age of death and a standard/expected age of death
• Deaths at younger ages will therefore have a larger effect on this value

Question 11

What is a disability adjusted life year?

Answer 11

• Quantitative indicator of disease burden

- Number of years lost due to ill health, disability, or early death

Question 12

What is a quality adjusted life year?

Answer 12

• value from 0-1 assigned to a year based on perceived quality of life
• A year of perfect health = 1
• A year of ill-health lowered based on disease burden
• Possible to have QALY less than one for serious conditions