Lecture 10- Descriptive Epidemiology Flashcards
(27 cards)
What is descriptive epidemiology
Classifies the occurrence of disease according to following variables:
Person, place, time
What are study designs in descriptive epidemiology
Case report, case series, cross-sectional
Case report
In-depth study of one case, no comparison group
Case series
Three or more cases involving patients that were given similar treatment, no comparison group
Cross-sectional
Looks at data at a single point in time, participants are not selected based on outcome or exposure status, just based on inclusion/exclusion criteria
What is an ecological study
Special type of cross-sectional study. Study in which the units of analysis are populations or groups of people rather than individuals
What are some examples of ecological studies
Incidence of disease following vaccination programs
How tobacco taxes effect tobacco use
Certain occupations and hearing loss
Cancer rates and dietary practices by country
What are the descriptive epidemiology measures
Count
Ratio: proportion, percentage, rate
Count (descriptive epidemiology)
Refers to number of cases of a disease or other health phenomenon being studied
Ratio (descriptive epidemiology)
Ratio is a relationship between two number
Proportion (descriptive epidemiology)
Comparison of a part to a whole, type of ratio in which the numerator is part of the denominator
Ex: proportion of deaths among men, proportion of lung cancer due to smoking
Percentage (descriptive epidemiology)
Proportion that has been multiplied by 100
Rates (descriptive epidemiology)
Compares 2 numbers, measures the frequency where event occurs in a defined population over a specific period of time
Ex: rate of breast cancer/1000 women or number of births/year
Population at risk (PAR)
The members of the overall population who are capable of developing disease or condition being studied, usually the denominator in rate calculation
Crude rate
Summary rate asked on the actual number of events in a population over a given time period
Ex: prevalence, incidence, morbidity rate, mortality rate
Specific rate
Based on particular subgroup of the population defined
Ex: race, age, sex, specific case
Better indicator of risk than crude rates especially for conditions specific to defined subsets of population
Adjusted rate
Measures where statistical procedures have been applied to remove the effect of differences in population distributions. Allows comparisons between groups having different population distributions for certain variables
Prevalence
Measure of the number of affected persons, number of persons with disease of interest, number of cases/number of people in population
Incidence
Number of new cases of diseases during a specific end time period, number of new cases/number of persons in population
What are factors that cause prevalence to icnrease
Increase in incidence, longer duration of the case, in-migration of cases, prolongation of life of patients without a cure
What factors cause prevalence to decrease
Decrease in incidence, shorter duration of disease, influx of healthy people into the population, improved cure rate of disease
Morbidity rate
Numerator is the total number of illness in a population over a specificed time, denominator is the average population at risk over the same time period
= number of illness due to the disease in the time period/average number in population during the time period
Can multiply by 10000 to get per 1000 rate of target population
Mortality rate
Numerator is the total number of deaths in a population over a specified time period, denominator is the average population at risk over the same time period
= number of deaths due to disease in the time period/average number in population during the time period
Can multiply by 1000 to get per 1000 rate of target population
What are limitations of crude rate
Sex, age, race
