Measuring + Describing Disease

Question 1

What is epidemiology?

Answer 1

How often diseases occur in different groups of people + why
(Study of the distribution + determinants of health related states or events in specified populations + application of this study to the control of health problems)

Question 2

What is endemic disease ?

Answer 2

Disease that resides in a population

Question 3

What is epidemic disease ?

Answer 3

Disease that befalls a population

Question 4

Who is known as the father of epidemiology? Why?

Answer 4

John Snow - prevented prevented spread of cholera in 1854

Question 5

What are the 3 types of disease prevention?

Answer 5

→ primary
→ secondary
→ tertiary

Question 6

What is primary prevention of disease?

Answer 6

→ before onset of disease

→ control of exposure to risk factors

Question 7

What is secondary prevention of disease?

Answer 7

→ slows progression of disease
→ application of available measures to detect early departures from health and to introduce appropriate treatment and interventions

Question 8

What is tertiary prevention of disease?

Answer 8

→ enables return to functioning after insult

→

Question 9

What prevention does our health care service focus on?

Answer 9

→ secondary

→ tertiary

Question 10

What is “exposure” in epidemiology terminology?

Answer 10

→ variable that we are trying to associate with a change in health status
→ independent variable
→ e.g. a drug, behaviour or demographic characteristic

Question 11

What is “outcome” in epidemiology terminology?

Answer 11

→ the hypothetical result of being exposed to a particular variable
→ dependent variable
→ e.g. survival, mortality rates, hospitalisation, etc.

Question 12

What is a demographic transition model?

Answer 12

measures birth rate, death rate and total population over time, or 5 stages

Question 13

What is a epidemiologic transition model?

Answer 13

measures birth + death rates over 4 stages of demographic transition

Question 14

What was the first stage of epidemiologic transition?

Answer 14

pestilence + famine (pre-industrial revolution, up to 1800s)
→ urbanisation
→  constraints on food supply
→ high birth + mortality rate
→ low life expectancy at birth

Question 15

What was the second stage of epidemiologic transition?

Answer 15

receding pandemics (1800s-1900s)
→ agricultural development = improves nutrition
→ life expectancy increases
→ water, sanitation, hygiene
→ vaccination emerges
→ natural population increase as mortality rates decline

Question 16

What was the third stage of epidemiologic transition?

Answer 16

degenerative + man-made diseases (1950s - 2010s)
→ crude birth rate
→ lifestyle factors + NCDs predominate
→ environmental + global determinants drive obesity + other risk factors
→ tech = less physical labour
→ addiction + violence emerge

Question 17

What was the fourth stage of epidemiologic transition?

Answer 17

delayed degenerative diseases + emerging infections (2010s onwards)
→ health technology defer morbidity but increases financial cost
→ emerging zoonotic diseases
→ inequalities within + between countries

Question 18

What are the measures of frequency?

Answer 18

→ odds
→ prevalence
→ cumulative incidence
→ incidence rate

Question 19

What is the definition of odds?

Answer 19

the probability of an event to its complement

e.g. ratio of no. who have disease to no. who don’t

Question 20

How are odds calculated?

Answer 20

odds = no. of people with disease/no. of people without disease

Question 21

What is the definition of prevalence?

Answer 21

proportion of individuals in a population who have the disease or attribute of interest at a specific timepoint

Question 22

How is prevalence calculated?

Answer 22

prevalence = no. of ppl with disease / total no. of people in population

Question 23

What is cumulative incidence?

Answer 23

proportion of the population with a new event during a given time period

Question 24

How is cumulative incidence calculated?

Answer 24

no. new cases during period of interest / no. of disease-free individuals at start of time period

Question 25

What is incidence rate?

Answer 25

no. of news case per unit of person-time

Question 26

How is incidence rate calculated?

Answer 26

no. of new cases during follow-up period / total person-time by disease free individuals

Question 27

What is person-time?

Answer 27

measure of time contributed to the study by an individual

Question 28

What is direct standardisation?

Answer 28

dsf

Question 29

How is direct standardisation calculated?

Answer 29

→ no. of strokes / population in that variable (e.g. different age ranges) = rate
→ rate x standard population (expected population average across country for that variable) = expected rate
→ sum of total expected rates of each variable / total population = variable-standardised incidence

Question 30

What is indirect standardisation?

Answer 30

dsf

Question 31

How is indirect standardisation calculated?

Answer 31

→ total no. of procedures of each variable / national probability of events happening = expected no. of events
→ create a standardised mortality ratio = observed value/ expected value = SMR value