Epidemiological Studies
((Design strategies in epidemiological research))Introduction:
Research can be defined as "the systemic search for information & new knowledge to solve a problem".The daily practice of medicine need the knowledge about who is likely to develop a particular condition and under what circumstances, what is the best treatment, what is the prognosis, and how we can prevent such illness.
Health care providers must be able to identify persons who are at high risk to reduce that risk. This type of knowledge emerges in many cases from epidemiological researches.
Epidemiology is the basic scientific tool with which public health professionals use to study health status, diseases, medical interventions & the effectiveness of health delivery services. It is a perspective in which systematic observation is the basis on which grounded inferences can be made about observed-phenomena.
Aims of medical (epidemiological) research:
Monitoring and surveillance of health and disease
Establishing causes of disease or factors associated with death or disease
Detecting disease
Preventing death or disease
Evaluating treatments for disease.
Evaluating health services & programs.
Learning objectives;
To under stand the concepts of different study designs.To learn about the advantages & disadvantages of each study design.
To appropriately use a study design in research projects.
It is important to:
1- Determine the study question.
2- Determine the exposure & outcome precisely.
3- Remember that the choice of any study design based on:
Features of exposure &outcome.
Time & resources available.
Results from previous studies.
Gaps in the knowlege that remain to be filled.
(No study design is fit for all types of studies)
4- Take care about sampling method (proper sampling procedure).
2x2 table to asses the relationship between an exposure & an outcomeOutcome Total +ve -veExposure +ve a b a+b -ve c d c+d Total a+c b+d Pop. (N)
(a+b+c+d)
The basic design strategies used in epidemiological research can be broadly categorized into:-
I- Descriptive studies. Describe occurrence of out come
1- Popular: Correlational studies.
2- Individual: a-Case-series b- Case-report C-Cross-sectional
II- Analytic studies. Describe the association between the exposure & the outcome.
1- Observational studies.
a- Case-control study.
b- Cohort study.
2- Interventional study {Clinical trail}.
Depart. Of Comm. Med. General Epidemiology
د.احمد . ِِAl-Kindy College of Med