Measuring and Describing disease

Question 1

defn epidemiology

the study of the ____ and ____ of health-related states/events in _____, and the _____ of this study to the control of ______

(how often diseases occur in different groups of people and why)

Answer 1

the study of the distribution and determinants of health-related states/events in specified populations, and the application of this study to the control of health problems

simple defn :(how often diseases occur in different groups of people and why)

Question 2

Stages of epidemiologic transition?

Answer 2

1- pestilence and famine - birth rate and death rate 1800s

2- receding pandemics: crude death rate falls- population size increases

3- degenerative and man-made diseases- crude brith rate falls : obesogenic environment

4- delayed degenerative diseases and emerging infections

• threat of zoonosis
• inequalities between and within countries

Question 3

exposure

Answer 3

variable

Question 4

outcome

Answer 4

health outcome like mortality at 5 years

Question 5

population pyramids

Answer 5

triangle : rapidly growing : youthful population

pentagon : straight sides - stationary = more people living to old age

contracting shape : widest at top , older age groups = low brith rate

zero growth : pentagon with wider at top : spain

Question 6

types of exposures?

Answer 6

drug, behaviour, demographic characteristic

Question 7

what problems were faced in the pestilence and famine era?

Answer 7

urbanisations
constraints on food supply

high birth and high mortality rates
life expectancy low at birth

Question 8

life expectancy

Answer 8

expected age to live at birth

Question 9

life span

Answer 9

how long you actually live not average of the population

Question 10

receding pandemics are defined by?

Answer 10

Agricultural development improves nutrition

Water, sanitation, hygiene
Vaccination emerges

High birth rate and reducing mortality
Life expectancy increasing

Question 11

degenerative and Man-Made diseases

Answer 11

Lifestyle factors and NCDs predominate: cancer and CVD
Environmental and global determinants drive obesity and other risk factors
Technology reduces need for physical labour
Addiction, violence and other issues emerge

Question 12

delayed degenerative diseases and emerging infections

hybristic

Answer 12

Health technology defers morbidity, albeit at increasing financial cost
Emerging zoonotic disease presents new threats
Inequalities within and between countries come to the fore

Question 13

DALY

Answer 13

Disability Adjusted Life Years
The DALY is a measure of disease burden that combines years of life lost from ill-health, disability or premature death. Like any other epidemiological measure, it’s not perfect, but it tells us a story.

Question 14

3 groups of conditions ?

Answer 14

NCD
Communicable diseases
and Injuries

Question 15

15-49.

What’s the leading cause of morbidity (using DALYs as the measure)?

Answer 15

back pain

Question 16

Which cause of death accounts for the greatest modifiable behavioural risk among 15-49 year olds?

Answer 16

Drugs

Question 17

odds

Answer 17

The ratio of the probability (P) of an event to the probability of its complement (1-P)

discrete data only
disease/ no disease

Question 18

Prevalence

Answer 18

The proportion of individuals in a population who have the attribute at a
specific time point

Question 19

Cumulative Incidence

Answer 19

New events ; people that already have it cannot be included in numerator or denominator

has no units

Question 20

what are drawbacks of cumulative incidence?

Answer 20

follow up is needed

same for all participants and no new participants can enter study population

competing risk : cannot be assessed if follow up lost due to death etc

Question 21

incidence rate

Answer 21

new cases at a specific time, person time allows for loss to follow up

Question 22

prevalence drawbacks

Answer 22

with disease/ total number of people in population
proportion - at a specific time

no info on new/developing cases

Less helpful in diseases of short duration and causal inference

Question 23

use of prevalence

Answer 23

assess’s health of a population

monitor trends over time

enable planning of health services and healthcare resources

Question 24

standardisation

why?

Answer 24

We want to understand whether the difference in incidence might be down to their different demography: sex and age.

Question 25

Direct standardisation –

Answer 25

this gives a similar incidence - eg. 120 strokes per 100k/yr

Question 26

unwarranted variation

explained variation

statistical artefact

Answer 26

Hospital A is dangerous – unwarranted variation.

Hospital A has a higher risk blend of procedures and therefore may have higher frequency of deaths - explained variation.

Hospital A is better at recording deaths than other hospitals; deaths outside hospital can be difficult to establish / link – statistical artefact.

Question 27

Standardised Mortality Ratio (SMR)

Answer 27

can be calculated by dividing the observed count by the expected count

 We observed (O) 43 deaths
We expected (E) 26 deaths

Therefore the O:E is 43/26 = SMR = 1.65
Alternatively we can present this as 165

Question 28

Standardised moratlity ration

standardised incidence ration

Answer 28

SHMI data for hospital performance identifying hospitals that report higher than expected mortality
Standardised mortality ratio (SMR<75) as a marker of healthy life expectancy

Question 29

granular data?

Answer 29

individual-level patient data

Question 30

aggregated datasets

Answer 30

ecological studies

top-level outcomes for a population- how many people died in crude numbers rather than who died