1 Epidemiology Basics

Question 1

what is a risk factor

Answer 1

• attribute, characteristic or exposure

- increases the likelihood of developing a disease or injury.

Question 2

what is an upstream factor

Answer 2

a factor affecting an outcome that doesn’t necessarily occur at the direct level of causation but is on a larger scale.

Question 3

what is a necessary risk factor

Answer 3

• Is not present if the disease is not present.
• Disease is only present when this is present.
• NECESSARY for the disease to occur.

Question 4

what is a sufficient risk factor

Answer 4

This factor alone is enough to cause the disease.

Question 5

necessary sufficient exmaples

Answer 5

poo

Question 6

Temporality

Answer 6

MOST IMPORTANT
Does the cause proceed the effect
Does this cause that

Question 7

Reversibility

Answer 7

Does removal of a cause decrease the observed effect?

Question 8

Dose response

Answer 8

Is there a change in effect with a change in dose?

Question 9

Strength of association

Answer 9

Measurement of the association between presumed cause and effect.

Question 10

Plausibility

Answer 10

Is the association consistent with existing knowledge? Can you explain the relationship biologically?

Question 11

Consistency

Answer 11

Have similar results been shown in other studies beyond your experiment?

Question 12

What is mortality

Answer 12

Mortality is death or the state of being subject to death.

incidence rate of fatal cases in the total population at risk during a specified time period.

number of deaths during the period / total population.

Question 13

what is a crude measure

Answer 13

measures that do not rely on all the information gathered and just spit out a sometimes uninformed statistic that doesn’t apply to the situation.

Question 14

what is morbidity

Answer 14

Morbidity is any departure subjective or objective from a state of physio- or psycho-logical well being.

Prevents you from doing your best

incidence rate of nonfatal cases of a disease in the total population at risk during a specified time period.

Question 15

Potential Years of Life Lost (PYLL)

Answer 15

No. of years of potential life lost if they die before a certain age.

PYLL = total no. of death from cause in age group x average no. of years of life lost as a result of each of these deaths (usually up to 65 years).

Question 16

Quality-adjusted life years (QALYs):

Answer 16

Weigh each year of life by the perceived quality of life from a value of 1 (perfect) to 0.

Question 17

Disability-adjusted life years (DALYs):

Answer 17

Measure of overall disease burden expressed as the cumulative no. of years lost due to ill-health, disability or early death.

DALY = years lived with disability (YLD) + years life lost (YLL)

Question 18

What is disability

Answer 18

any temporary or permanent reduction of a persons capacity to function (refers to functioning of body)

Question 19

What is person time

Answer 19

The cumulative time one or many participants contribute to a study.

(If the study studies life before the disease this is what is counted. If the study studies life after getting the disease this is what is counted).

Question 20

What is incidence

Answer 20

no. of new cases of a disease.

Cumulative incidence (proportion/%) = number of new events in a specified period / number of persons exposed to risk during this period

Incidence rate (time/rate) = new cases in a defined period / total person-time of follow up

Question 21

What is prevalence

Answer 21

a count of both new and existing cases of the outcome dependent on both the incidence and duration of disease

Point prevalence: prevalence literally at one point in time. Cases/people studied (at risk)

Period prevalence: prevalence measured over a short period of time. Old cases + new cases / people studied (at risk)