Fundamentals of epidemiology prof najeeb memon

1. Fundamentals of Epidemiology

2. PROF: NAJEEB MEMON
MBBS, DFHC, MPH, (PhD)
Community Medicine Deptt:
BMC, LUMHS

3. Epidemiology

4. Epidemiology
"The study of the
distribution
& determinants
of health-related states or events
in specified
populations,
and the application of this study to the
control of health problems".
Epidemiology (epi =upon ,demos =
population)

6. How Distribution
and
Determinants are
studied1) Disease Frequency:
By Rates and Ratios.
2) Distribution of Disease:
By Time, Place & Person.
3) Determinants of Disease:
Identifying underlying cause.

8. Epidemiological studies
Observational .S
(Only measures not
intervene)
Experimental.
S/
Interventions .
S
Descriptive
or
situ: analysis
(occurrence of dis: )
Analytical /
comparative
(Analysis health status
& variables)
Randomize
d clinical
trials
Field Trials
Community
Trials
Cohort/ follow up
Case control
Cross sectional
Ecological
/correlation

9. USES OF DESCRIPTIVE EPID:
 It helps to know the Extent / Magnitude of
Dis: (Morbidity & Mortality Rates)
 It helps to know distribution of a disease in
the community (Person, Place & Time)
 Helps to formulate an etiological
hypothesis.
 Helps to plan, organize & implement
curative & preventive services.

11. Important Issues that
Epidemiology can Address
Disease
Mortality
Hospitalization
Disability
Quality of Life
Health Status

12. Leading Causes of Death Worldwide,
2000
(Based on number of global deaths)
1. Ischemic Heart Disease
2.Cerebrovascular Disease
3.Lower Respiratory Infections
4. HIV/AIDS
5. COPD
6. Perinatal Conditions
7. Diarrhoeal Diseases
8. Tuberculosis
9. Road Traffic Injuries
10. Lung Cancers
WHR 2001

13. Clinician Epidemiologist
Patient’s
diagnostician
Investigations
Diagnosis
Therapy
Cure
 Community’s
diagnostician
 Investigations
 Predict trend
 Control
 Prevention

15. Typical Study Design: Comm: Health
Survey / Des.S
Typical Study Design: Cohort & Case -
control. S

16. • Simplest form of Observational study.
Cross-sectional study
Based on:
• Single exam: of
• Cross- section of population
• at one point in time / specific point in time

17.  Collects data at one point in time
 What exists today
 More useful for Chronic Diseases.
Cross-sectional study

18. Exposure and Disease Measures simultaneously

19. 3 essential characteristics of disease that
we look for in descriptive studies are...

20. Person (Who)
Age
Sex
Race/Ethnicity
Socio-Economic Status
Behaviors

21. Place (Where)
presence of agents or
vectors
climate
geology
population density
economic development
nutritional practices
medical practices

22. TimeTime distribution:-
 Pattern of disease may be described by time of its
occurrence by
 Year
 Month
 season
 Week
 Day etc
 Whether it shows periodic increase or decrease or
it follows constant time trends.
 Such clues show about the source or etiology of
dis:
Calendar time
Time since an event
Secular trend
Seasonality
Temporal trends

24. Emphasis on relationship of disease to the host,
the agent and environmental factors.
EPIDEMIOLOGICAL
TRIAD3 essential characteristics that are examined to study the
cause(s) for disease

25. Epidemics arise when host, agent, and environmental
factors
are not in balance

26. Age, Sex, Race, Religion,
Customs,
Occupation, Genetic profile,
Marital
status, Family background, Prior
diseases, Immune status
Temperature, Humidity,
Altitude
Crowding, Housing,
Neighborhood, Water,
Radiation, Noise, Air
pollution
Behavioral (malnutrition,
physical exercise,
smoking, alcohol),
Biologic (bacteria, viruses),
Chemical (poison, smoke),
Physical (trauma, radiation, fire),
ENVIRONME
NT
(Factors)
AGENT
(Type & Examples)
HOST- Individual
vulnerability
Age, Sex, Race, Religion,
Customs, Occupation,
Genetic profile, Marital
status, Family background,
Prior diseases, Immune
status
The Epidemiologic Triangle Underlying the
Outcome

27. Incidence
Rate
Prevalence Rate

29. Epidemiologic Activities
 …are often framed under the mantle of
descriptive and analytic epidemiology
◦Descriptive epidemiology
(person, place & time)
 Demographic distribution
 Geographic distribution
 Seasonal patterns etc.
 Frequency of disease patterns
◦Useful for:
 Allocating resources
 Planning programs
 Hypotheses development

30. Epidemiologic Activities
Analytic epidemiology
built around the analysis of the
relationship between two items
 Exposures
 Effects (disease)
◦looking for determinants or
possible causes of disease
◦useful for
 hypothesis testing

31. Thank you