Epidemiology: Measuring and Describing Disease Flashcards
What are the 3 types of prevention?
Primary - the prevention of disease through control of exposure to risk factors (BEFORE ONSET)
Secondary - the application of available measures to detect early departures from health and to introduce appropriate treatments and interventions (HALT PROGRESSION)
Tertiary - the application of measures to reduce or eliminate long-term impairments and diabilities, minimising suffering caused by existing departures from good health and to promote the patient’s adjustment to their condition. (RETURN TO NORMAL)
What are exposures and outcomes?
An exposure is essentially the variable that we are trying to associate with a change in health status. The outcome is the resultant change in health status or a marker of health status change we are investigating with relation to the exposure.
Relate stage of epidemiologic transition to stage of demographic transition
In the pre- stage of demo trans, epidemiological transition is in pestilence and famine stage. Birth rates remain relatively constant and death rates fluctuate. In the early stage of demo trans, there are receding pandemics (epi trans) with a large decrease in death rates and birth rates remain constant so natural increase occurs. In late stage of demo trans, degenerative and man-made diseases dominate so death rates remain constant while birth rates rapidly decrease. In the post- stage of demo trans, delayed degenerative diseases and emerging infections dominate so both birth rates and death rates fluctuate.
What are the 3 dimensions epidemiology can be described in?
Most epidemiology can be described in three dimensions: time, person and place.
What is the purpose of the demographic transition model?
Demography is a closely related discipline to epidemiology: the epidemiologic transition model demonstrates how populations, health and disease change over time.
What is morbidity vs mortality?
Morbidity is the state of having an illness while mortality is rate of death or causes of death.
What type of data are measures of frequency used for?
Discrete data
What are the 4 measures of frequency?
Odds, prevalence, cumulative incidence and incidence rate
Define odds
The ratio of the probability of an event to its complement. Number of people who have disease/ Number of people who don’t have disease
Define prevalence
The proportion of individuals in a population who have a disease or attribute of interest at a specific timepoint Number of people with disease/ Total population. MUST SPECIFY TIMEPOINT.
What are weaknesses of using prevalence?
As it is dependent on a timepoint, number may be higher or lower than calculated prevalence at varying times depending on duration of illness event. Also doesn’t provide info on new cases of any disease. Therefore, not of use in studying acute illnesses or deriving causal inference.
Define cumulative incidence
Proportion of the population with a new event during a given time period. Number of new cases in period of interest/Number of disease-free individuals at the start of this time period. No units - takes values from 0-1. Can only be calculated if there is a follow-up.
Define person-time
Measures the time participants spend in a study
Define incidence rate
Number of new cases during follow-up period/ Total person time by disease free individuals
What are the 2 types of standardisation?
Direct standardisation - uses comparable incidence
Indirect standardisation - uses ratios out of 100
