Lecture 3: Epidemiology: How do we measure disease? Flashcards
(40 cards)
What is epidemiology?
Science of DISTRIBUTION and FREQUENCY of disease
What does Distribution of disease involve?
- Person
- Place
- Time
What does frequency of disease involve?
Incidence and Prevalence
What can epidemiology do
DEPC:
Describe, explain, predict, control
Describe in DEPC
Describe health of a population
Explain in DEPC
Explain etiology (cause) of disease
Predict in DEPC
Predict occurrence of disease
Control in DEPC
Control distribution of disease
What are the assumptions of epidemiology?
- Disease does not occur randomly
- Disease has causal and preventative factors that we can
identify through systematic investigation of different
people at different places or times
What are the 3 types of epidemiology?
- Descriptive
- Analytic
- Experimental
What is the goal of descriptive epidemiology?
To examine patterns of disease, health behaviours)
What is the goal of analytic epidemiology
To evaluate relationships between risk/protective factors and disease
What is the goal of experimental epidemiology?
To evaluate effect of treatment/intervention on disease
What is the foundation for all the types of epidemiology?
Foundation for all is being able to MEASURE PATTERNS (OCCURRENCE) OF DISEASE
What are the types of measures of disease occurrence?
- Rank
- Count(s)
- Ratio
- Proportion
- Rate
What is the key consideration for count, ratio, proportion, and rate?
Who, what is in numerator and/or denominator
What does rank measure?
Measures the order of disease
occurrence
ex. Arthritis and other rheumatic
conditions are a leading cause of
work disability among US adults
* Diabetes is the 7th leading cause of death in the US
What does count measure?
Measure(s) the number of
persons who have a given
disease (no denominator)
Ex. Number of female(s) with disease
X (red)
What is a ratio? What does it allow for?
The quotient of two numbers
- Numerator not necessarily included in denominator (no specific relationship between numerator and denominator)
- Allows comparison of quantities of different nature
- Ex. male to female ratio
Measures of association in epidemiologic students are?
Ratios
* Relative risk (RR) (or Rate ratio or Risk ratio)
* Odds ratio (OR)
What is a proportion?
- The quotient of 2 numbers
- Numerator is necessarily included in the denominator
- Expressed as a fraction, decimal, or percentages
What is rate?
- The quotient of two numbers
- Numerator
- Number of ‘events’ (new cases
of disease) observed for a given
time
- Number of ‘events’ (new cases
- Denominator
- Population in which events occur
- Includes time
- Ex. 1/10 = 0.1 per year
- 5-year cancer survival rate
- Ratio of people who are alive for 5
years after cancer diagnosis to
people in the general population
who are alive over the same 5 year
interval
What is prevalence?
- All individuals affected by disease at a particular time
- “Refer to individuals as “prevalent cases” or “active cases”
What is Incidence?
- New individuals with a disease during a particular period of time
- Refer to individuals as “incident cases” or “new cases”
