Measuring And Describing Disease Flashcards
Epidemiology
The study of the distribution and determinant of health related states or events in specified populations and the application of this study to control health problems
How often diseases occur in different groups of people and why
Prevention types
Primary:preventing disease through controlling exposure to risk factors eg reducing salt in diet to prevent hypertension
Secondary:the application of available measures to detect ill health and introduce treatments eg controlling hypertension with antihypertensive drugs
Tertiary:the application of measures to reduce or eliminate long term impairment and disability eg rehabilitation if someone who’s had a stroke so they can go back to normal,
Exposure and outcome
the variable that we are trying to associate with a change in health status. For example, in a study of cancer outcomes, we might look at Drug X (the exposure) and test its association on mortality at five-years (the outcome).
Epidemiological transition
Perstilence and famine
Constrains on food supply so high birth and death rate. Life expectancy was low at birth.
Receding pandemics
Improved nutrition hygeine water vaccination emerges so high birth rate and less mortality
Degenerative and man made diseases
Non communicable diseases created,technology increases,addiction,violence increases
Delayed degenerative diseases and emerging infections
Zoonotic disease threat
Inequalities in countries
Odds
Number of people with disease/number of people without disease
The ratio of the probability (p)of an event to the probability of its complement (1-p)
Prevalence
Proportion of individuals that have the disease at a specific time point
Number of people that have disease/population
Cumulative incidence
Proportion of population with a new event during a given time period
Number of new cases during period of interest/number of disease free individuals at the start of this time period
Exclude people who already have disease in that time frame from numerator and denominator. Eg if a person was already sleeping at 11 in a class of ten and 5 new people slept it would be 4/9
Incidence rate
Number of new cases during follow up period/total person time by disease free individuals at
Expressed as person years person days person hours
Direct vs indirect standardization
Direct gives comparable incidence eg 120 strokes per 100k/yeae
Indirect gives a ratio out of 100 or 1
Standardized rate
If the crude rate increases when standardized it means original population was young, if the crude rate decreases then population is older
Direct standardization
Requires that you know variable specific measures – such as age specific incidence in the institution or geography of interest – in order to conduct the standardisation
Indirect standardization
Requires that you know a benchmark measure – such as national incidence rate – in order to conduct the standardisation by applying the national age-specific incidence against the age structure of the institution or geography of interest.
If standardising incidence rate, outputs in units of count / time.
Direct standardization
If standardising incidence rate, outputs as a standardised incidence ratio
Indirect standardization
If an occupation reports a standardised mortality ratio (SMR) of 1.00 (or 100), this can be interpreted as:
Mortality is as expected
