1 Epidemiology Basics Flashcards
what is a risk factor
- attribute, characteristic or exposure
- increases the likelihood of developing a disease or injury.
what is an upstream factor
a factor affecting an outcome that doesn’t necessarily occur at the direct level of causation but is on a larger scale.
what is a necessary risk factor
- Is not present if the disease is not present.
- Disease is only present when this is present.
- NECESSARY for the disease to occur.
what is a sufficient risk factor
This factor alone is enough to cause the disease.
necessary sufficient exmaples
poo
Temporality
MOST IMPORTANT
Does the cause proceed the effect
Does this cause that
Reversibility
Does removal of a cause decrease the observed effect?
Dose response
Is there a change in effect with a change in dose?
Strength of association
Measurement of the association between presumed cause and effect.
Plausibility
Is the association consistent with existing knowledge? Can you explain the relationship biologically?
Consistency
Have similar results been shown in other studies beyond your experiment?
What is mortality
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.
what is a crude measure
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.
what is morbidity
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.
Potential Years of Life Lost (PYLL)
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).
Quality-adjusted life years (QALYs):
Weigh each year of life by the perceived quality of life from a value of 1 (perfect) to 0.
Disability-adjusted life years (DALYs):
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)
What is disability
any temporary or permanent reduction of a persons capacity to function (refers to functioning of body)
What is person time
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).
What is incidence
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
What is prevalence
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)
