Why should medical students be interested in EPIDEMIOLOGY? Very basic concepts
Dec 15, 2015
Why should medical students be interested in
EPIDEMIOLOGY?
Very basic concepts
What is EPIDEMIOLOGY?Epidemiology is the study of the distribution a
nd determinants of health-related states or events in specified populations, and the application of this study to control of health problems.
Last ed. Dictionary of Epidemiology
But can you imagine what is epidemiology like in clinical practiceby reading definition?
Let's see some examples
First, I will show you observational data of mortality.
Mortality in Area A and Area B
Area A Area B
dead/population
500/10,000 1000/10,000
mortality 5% 10%
If you categorize the populations by age and compare mortality of Area A
with that of Area B
area A area B
age<60dead/
population
500/10,000 250/5,000
mortality 5% 5%
60=<agedead/
population
0/0 750/5,000
mortality - 15%
The factors should be taken into consideration when you look at the data.
age sex race year of birth .
Answer
CDC revised classification system for HIV (AIDS) infection in 1993
Next example subjects:
smokers: 1000 non smokers: 1000 of same age range, sex ratio
status of lung cancer for 5 years were observed.
Results in 5 years
smokersnon
smokers
lung cancer/ 1,000
50/1,000 10/1,000
morbidity 5% 1%
If the sample size of both group is not 1,000, but
100.
smokersnot
smokers
lung cancer/ total
5/100 1/100
morbidity 5% 1%
Next example
lung cancer healthy
alcohol intake yes/
no71/29 52/48
yes/no ratio 2.45 1.08
p=0.006 by Chi-square test
Non-smokers
lung cancer healthy
alcohol intake yes/
no8/22 16/44
yes/no ratio 0.36 0.36
p=1.0 by Chi-square test
Smokers
lung cancer healthy
alcohol intake yes/
no63/7 36/4
yes/no ratio 9 9
p=1.0 by Chi-square test
Why should medical students beinterested in
EPIDEMIOLOGY?
Welcome to the world of Epidemiology