Epidemiology has seven main uses: 1. Studying disease trends over time to understand rises and falls in disease and identify emerging health problems. 2. Diagnosing health issues in communities to prioritize disease prevention and control and evaluate health services. 3. Planning and evaluating health services and programs by using disease burden data to allocate resources effectively. 4. Assessing individual risk levels by calculating disease incidence and relative risks. 5. Identifying disease syndromes by observing common associated findings. 6. Furthering understanding of disease natural histories by studying patterns. 7. Searching for disease causes and risk factors through epidemiological investigations.

1. Uses of epidemiology
Dr Basavaraj Mannapur
S N Medical College, Bagalkot

2. USES OF EPIDEMIOLOGY
EPIDEMIOLOGY IS
“A MEANS OF LEARNING, OR ASKING QUESTIONS AND
GETTING ANSWERS THAT LEAD TO FURTHER QUESTIONS”.
J.N.MORRIS HAS IDENTIFIED
THE SEVEN DISTINCT USES
OF EPIDEMIOLOGY

3. 1. To study historically the rise & fall of
disease
• Winston Churchill said:
The farther back you look, the farther forward
you can see
• Study the history of the disease
• Health & disease are not constant
• Fluctuations both over short & long periods of
time

4. • Old diseases are conquered, new diseases are
identified
• Provides a means to study disease profile &
time trends in human population
• By study of trends, we can make useful
projections into the future
• Identify emerging health problems

6. 2. Community diagnosis
• Identification & quantification of health problems
in a community in terms of mortality & morbidity
rates & ratios
• Identification of their correlates for the purpose
of defining those individuals at risk
• By quantification: priorities in disease prevention
& control
For evaluation of health services
Source of new knowledge about disease
distribution, causation and prevention

7. • Understanding of the social, cultural and
environmental characteristics of the
community

8. 3 Planning & evaluation
• Essential for allocation of limited resources
Eg: too many hospitals have been built and equipped
without knowledge of disease problems
• Epidemiological information about the distribution of
health problems provides basis for planning &
developing the needed health services
• Planning facilities for medical care Eg: No. of hospital
beds required for specific disease, health manpower
planning
• Planning facilities for preventive services: Eg-Screening
programmes, Immunization campaign, Planning for
research

9. • Measures taken to control or prevent the disease must
be followed by an evaluation
• To find out whether the measures undertaken are
effective in reducing the frequency of the disease
• All health services have to be evaluated
• The development of RCT has made it possible to
evaluate treatment modalities
• Such trials have raised doubts about utility of
multiphasic screening, prolonged hospitalization of MI
• Not enough to know that the programme provides
some benefit we need to know how much benefit & at
what risk & cost

10. 4. Evaluation of individual risk &
chances
• To make a statement about degree of risk
• The epidemiologist calculate Incidence rates,
specific rates which are measures of absolute risk
also calculates relative risk & attributable risk for
a factor related to the cause of disease
• Eg: Risk of some hereditary disorders are
examples of evaluating individual risk and
chances
Risk assessment for smokers & non smokers,
Cancer, CHD

11. 5. Syndrome identification
• Identified by observing frequently associated
findings
• Epidemiological investigations can be used to
define & redefine syndromes
• By observation of groups, such studies have
been able to correct misconceptions
concerning syndromes

12. 5. Completing the natural history of
the disease
• The epidemiologist by studying the disease
pattern in relation to epi. Triad is in a better
position to fill up the gaps in natural history of
disease
• Eg: atherosclerosis
Recognition that 1/3 to 2/3 of all deaths due to IHD
are sudden, occur in < 1hr
Hospital studies could never have come to this
conclusion
Led to the development of ICCU

13. • Epidemiological investigations have yielded
large amount of data on risk factors in relation
to chronic disease

14. 7. Searching for causes & risk factors
• Tried to identify the causes of disease
• Rubella is the cause of congenital defects in
newborn
• Thalidomide is a teratogenic agent
• Cigarette smoking is the cause of lung cancer
• Search for the risk factors in non
communicable diseases

15. RUBELLA IS THE CAUSE OF CONGENITAL DEFECTS IN NEW BORN
EXPOSURE OF PREMATURE BABIES TO O2 IS THE CAUSE OF RLF.