Analytic studies

The type of the study used for analysis and investigation of a relation between an exposure and outcome in the community.

1. ANALYTIC STUDIES Prepared By: Dr.Anees AlSaadi CMT-P R4 December 2013

2. ANALYTIC STUDIES OUTLINE: Hierarchy of Study design. Introduction for analytic Studies./ Exposure & Outcome. Cohort and Case control Study design: Definition. Character. Advantages and disadvantages.

3. ANALYTIC STUDIES Introduction

4. ANALYTIC STUDIES Introduction: Testing specific hypotheses. Samples of subjects are identified and information about exposure status and outcome is collected.

5. ANALYTIC STUDIES Introduction: Groups of subjects are compared in order to estimate the magnitude of association between exposures and outcomes.

6. ANALYTIC STUDIES Introduction: The two main types: Cohort study Case-control study

7. ANALYTIC STUDIES Introduction: Exposure Outcome

8. ANALYTIC STUDIES Cohort study: Exposure Outcome

9. ANALYTIC STUDIES Cohort study: Definition

10. ANALYTIC STUDIES Cohort study: Definition

11. ANALYTIC STUDIES Cohort study: Definition . Is an analytic epidemiologic research design in which the study population is composed of individuals who are classified as exposed and no exposed to particular risk factors. These groups are followed forward for a specific period of time to estimate the incidence rate of an outcome or the development of a health problem.

12. ANALYTIC STUDIES Cohort study: Hypothesized to be at greater risk or lesser risk of developing the health problem

13. ANALYTIC STUDIES Cohort study: What is t he Potential Source of Study Subjects…… ?

14. ANALYTIC STUDIES Cohort study:

15. ANALYTIC STUDIES Cohort study:

16. ANALYTIC STUDIES Cohort study: Example

17. ANALYTIC STUDIES Cohort study: The most important bias is loss of follow ups (drop out).

18. ANALYTIC STUDIES Cohort study: Advantages: More control on data collection. Easy checking the study outcome. Clear temporal sequence. Estimating the risk. Good to study rare risk factors. Can study different disease or outcomes. Disadvantages: Only risk factors defined at the beginning of the study can be studied. Costly. Time consuming. For common diseases. The exposure status may change during the study. Loss of follow up.

19. ANALYTIC STUDIES Case Control Study: Definition It is analytic type of epidemiologic research design in which the study population consists of groups who either have ( cases) or do not have (controls) a particular health problem or outcome.

20. ANALYTIC STUDIES Case Control Study:

21. ANALYTIC STUDIES Case Control Study: The investigator selects the case and the control group on the bases of the outcome and compares them in term of their frequency of past exposure to the possible exposure.

22. ANALYTIC STUDIES Case Control Study: Retrospective Study

23. ANALYTIC STUDIES Case Control Study:

24. ANALYTIC STUDIES Case Control Study:

25. ANALYTIC STUDIES Case Control Study:

26. ANALYTIC STUDIES Case Control Study:

27. ANALYTIC STUDIES Case Control Study: Selection of controls: No outcome. Selection randomly or Systematic. Matching on specific variables./individual or frequency. Restriction.

28. ANALYTIC STUDIES Case Control Study : What is t he Potential Source of Study Subjects…… ?

29. ANALYTIC STUDIES Case Control Study: The most important bias is recall .

30. ANALYTIC STUDIES Case Control Study: Advantages : Quick design saves time. Easy to perform. Inexpensive. Suitable for rare diseases. Can study many risk factors. Useful for generating hypothesis. Disadvantages Recall bias. Can not be used for incidence rate. Temporal relationship. Can study only one disease outcome. Can only obtain relative measure of risk.

31. Practical Exercise

32. T h ank y o u