COMMUNITY DENTISTRY

General Epidemiology


Definition :-
The study of the distribution and determinants of health related states as events in specified population and the application of this study to the control of health problems.
Definition was given by John M. lat in 1988 which is found to be one most commonly used in literature.

Aims of Epidemiology:-
 To describe the size and distribution of the disease problem in human population.
 To provide the data essential for the planning implementation and evaluation of health services for the presentation, control and treatment of disease and for the setting up of priorities among those services.
 To identify etiological factor in the pathogenesis of disease.

PRINCIPLE OF EPIDENIOLOGY:-
 Exact observation (Strict, Vigorous, Accurate, Precise)
 Correct Interpretation (Free from Errors)
 Rational explanation (Intelligent, sensible, reasonable)
 Scientific Construction (By expert knowledge and technical skill)

TOOLS OF MEASUREMENT IN EPIDENILOGY:-
The most commonly used tools of measurement in Epideniology are-
 Rates
 Ratios
 Proportion

 Rate:-
A Rate is the frequency of a disease as characteristic expressed per unit size of the population.

 Ratio:-
Ratio denotes the relation an size between two sandom quantities. In simples terms. The ratio can be expressed as the result of one quantity divided by the other.

 Proportion:-
A Proportion is a ratio which expresses the relation in magnitude of a part of the whole.

Basic measurement in epidemiology:-
The most commonly used measurement is epidemiology are

 Measurement of Neortality
 Measurement of Morbiding

Mortality is the condition of being mortal, as susceptible to death.

Factors Affecting mortality rate:
 Bith Rate
 Density of population
 Geographical
 Season
 Epidemic Experience
 Secular Variation

Mosbiding :- WHO has eleyined “Morbiding” as “any departere, subjective or objective, from a state of physiological well-being.

The disease frequency is measured by means of incidence and prevalence

Incidence- it can be defined as the number of new cases of a specific disease occurring in a defined population during a specified period of time.

The two different varieties of incidence are:-
1) episode incidence- It is sate of occurrence of new episode of a disease arising in population
2) cunculative incidence – It is similar to incidence but the time interval is expressed as a forced period & result is expressed as a proposition

Use of incidence rates:-
It gives clues to research into the etiology & pathogenesis of disease

PREVALENCE
The term disease prevalence is used to indicate all current cases (both old and new) existing in a given population at a given point to time or oves a period of time

Prevalence is of 2 types:-
1) point prevalence
2) period prevalence
Relationship between prevalence & incidence

Incidence - Prevalence
- Duration

Epidemiological Methods:-
The 3 types of methods are,
 Escriptive Epidemiology
 Analytical Epidemiology
 Experimental Epidemiology

The 3 types of epidemiological methods complements one another. The descriptive and analytical studies are after called as “observation studies”

Descriptive epidemiology:-
They are usually the first phase of any epidemiological investigation. These studies are confirmed with the observation of the distribution by the disease or any health related events in human populations and the celetifishon of the characteristic with which the disease or condition under study seems to be associated.

Longitudnal studies :-
In longitudions study the same individual are examined upon sepeated occusions and the changes withing the group secoreled in terms of elapsed time between observation.

Analytical Epidemiology :-
They are the second major types of epidemiological studies. The focus here is the individual within a population unlike the deceptive epidemiology which focuses on the eatue population.

They are of two types:-
 Case Control Study.
 Cohert Sheely

Case control is called as Ratiospective study or backward studies.

In this type, disease has already occurred we go to from effect to cause and hs central group to compace or support.

Advantages:-
 Easy to carry out less time cousuming cost effective
 Number of subject / sample size is less.
 No suck involved is the subject.

Disadvantage:-
Careful selection of central group is important.
Diffiaact to differentiate between etiological factor and association factors.

Cohorl Study (Prospective / forward study)
Cohart – group of people sharing common chrematistic or experiences is defined period of time.
Advantages :-
We can check your incidence.

Disadvantages:-
Time consuming (Studying the whole population)

Experimental Epidemiology:-
Experimental or intervention studies are studies carried out under the direct control of the investigator.

Steps of Epidemiological studies:-
 Extablishing Objective of the disease (has to be very clear)
 Designing the study
 Selection of sample
 Econducting examination – indices
 Analysis of the data ( incuse collection arranging, analyzing information that is collected)
 Drawing the conclusion
 Publishing the result (Add to the history of investigation)

Use of Epidemiology :-
Epidemiology concentrates on disease distribution and causation in depth. So as to context the future consaught by disease and risk factors:-
 Community diagnosis
 Rise and fall of disease
 Planning and Evaluation
 Evaluation of individual risk.