Descriptive Epidemiology : Study About Epidemiology and Complete Description
Definition
Descriptive epidemiology is one of the basic types of epidemiology, which is concerned with describing the frequency and distribution of diseases and other health related conditions by time, place, and person. The other branch of epidemiology which deals with the causes or determinants of diseases is called Analytical Epidemiology. It asks the questions: how? Why?
The major variables in Descriptive Epidemiology
The major variables in descriptive epidemiology can be classified under the headings: person, place and time. To describe the occurrence of a disease fully, the following questions must be answered.
Who is affected? Where and When do the cases occur?
Person
People can be categorized with respect to many variables. In Epidemiologic study it is common to specify three characteristics of a person – age, sex and ethnic group or race.
Age: Age is the most important determinant among the personal variables. Example: Measles affects children.
Sex: There are some diseases which are common among females. For example breast cancer is a disease of females.
Ethnic group and Race: Many diseases differ markedly in frequency, severity, or both in different racial or ethnic groups.
Other personal variables: There are also other personal variables that should be considered during epidemiologic studies. This includes social class, religion, occupation, marital status, environmental exposure etc.
Place
The frequency of disease is different in different places. These differences can occur because of the natural boundaries (e.g. mountain range, rivers, deserts). An area defined by natural boundaries may have a high or low frequency of certain diseases because it is characterized by some particular environmental or climatic conditions, such as temperature, humidity, rainfall, altitude, mineral content of soil, or water supply. For example - Malaria is common in low lands but relapsing fever is common in highlands.
Time
Study of disease occurrence by time is a basic aspect of epidemiologic analysis. Occurrence is usually expressed on a monthly or annual basis. Some diseases occur periodically or cycles. Cycles may be annual have some other periodicity. The most common types of periodicity are in relation to seasonal changes, or in relation to changes in the number of susceptible persons in a population.
Malaria is one of the example of diseases with seasonal periodicity, where high peaks occur in relation to the rainy season. Epidemic of malaria are common in October and November, when stagnant water bodies are convenient for the breeding of mosquitoes.
Cross sectional study design (Survey)
Cross sectional study is the major type of descriptive study designs. It is mainly concerned with the distribution of diseases with respect to time, place and person. By conducting survey, the magnitude of diseases or other health related condition will be known. They are useful for priority setting, resource allocation etc.
In cross sectional studies, information about the status of an individual with respect to the presence or absence of exposure and disease is assessed at a point in time. The point in time may be as short as few minutes or as long as two or three months. The time frame of "point in time" is based on the speed of data collection.
If somebody wants to conduct a survey, he/she can follow the following procedures:
-Write the objectives of the survey
-Identify the methods of data collection. Data can be collected by using questionnaire, interview, selfadministered questionnaire, observation, applying laboratory tests etc.
-Recruit and train data collectors
-Calculate (determine) the number of people needed for the survey
-Collect the data
-Analyse the data
-Disseminate the findings
Advantages of cross sectional studies:
-are a one-stop, one-time collection of data
-are less expensive & easier to conduct
-provide much information useful for planning health services and medical programs
-show relative distribution of conditions, disease, injury and disability in groups and populations.
For example by conducting survey in different towns, it is possible to know which towns are highly affected by HIV/AIDS.
Thanks For Visiting ! Keep Your Healthy !
0 comments:
Post a Comment