Epidemiology is the study of how often diseases occur in different groups of people and why. Epidemiological information is used to plan and evaluate strategies to prevent illness and as a guide to the management of patients in whom disease has already developed.
Like the clinical findings and pathology, the epidemiology of a disease is an integral part of its basic description. The subject has its special techniques of data collection and interpretation, and its necessary jargon for technical terms. This short book aims to provide an ABC of the epidemiological approach, its terminology, and its methods. Our only assumption will be that readers already believe that epidemiological questions are worth answering. This introduction will indicate some of the distinctive characteristics of the epidemiological approach.
The distribution of disease occurs in patterns in a community. In epidemiology we study these distribution patterns in various subgroups of the population by time, place and person; that is:
A. Whether there is an increase or decrease of disease over time; whether there is a higher concentration of disease in one geographic area than in others
B. Whether the disease occurs more often in Men or in a particular age-group, and characteristic of those affected and not affected.
Study of these patterns may suggest or lead to measure to control or prevention of disease. Also one can formulate an etiological hypothesis of disease through these “descriptive epidemiology”.
Study of Epidemiology helps us in measuring the spread of disease, affected persons, how to prevent the disease from spreading. The following are the studies of Epidemiology:
(A) Observational studies:
Descriptive Studies
1) Case reports
2) Case series
3) Ecological/Correlation
4)