Types of Epidemiological Study : Community Medicine,PSM

Epidemiology studies are conducted using human populations to evaluate whether there is a correlation or causal relationship between exposure to a substance and adverse health effects.

These studies differ from clinical investigations in that individuals have already been administered the drug during medical treatment or have been exposed to it in the workplace or environment.

Epidemiological studies measure the risk of illness or death in an exposed population compared to that risk in an identical, unexposed population (for example, a population the same age, sex, race and social status as the exposed population).

There are four primary types of epidemiology studies. They are:

Cohort studies — A cohort (group) of individuals with exposure to a chemical and a cohort without exposure are followed over time to compare disease occurrence.
Case control studies — Individuals with a disease (such as cancer) are compared with similar individuals without the disease to determine if there is an association of the disease with prior exposure to an agent.
Cross-sectional studies — The prevalence of a disease or clinical parameter among one or more exposed groups is studied, such as:
The prevalence of respiratory conditions among furniture makers.
Ecological studies – The incidence of a disease in one geographical area is compared to that of another area, such as:
Cancer mortality in areas with hazardous waste sites as compared to similar areas without waste sites.