We previously discussed descriptive epidemiology studies, noting that they are important for alerting us to emerging health problems, keeping track of trends in the population, and generating hypotheses about the causes of disease. Analytic studies provide a basic methodology for testing specific hypotheses. The essence of an analytic study is that groups of subjects are compared in order to estimate the magnitude of association between exposures and outcomes. This module will build on descriptive epidemiology and on measuring disease frequency and association by discussing cohort studies and intervention studies (clinical trials). Our discussion of analytic study designs will continue in module 5 which addresses case-control studies. Pay particular attention to the strengths and weaknesses of each design. This is important for being able to select the most appropriate design to answer a given research question. In addition, a firm understanding of the strengths and weaknesses of each design will facilitate building your skills in critical reading of studies by alerting you to possible pitfalls and weaknesses that can undermine the validity of a study.
- What are the different strategies for investigating the causes or sources of health outcomes?
- How do we choose the best approach to study a particular health problem?
- What are the strengths and limitations of different study designs?
After completing this section, you will be able to:
- Explain the role of descriptive epidemiology for defining health problems and establishing hypotheses about the determinants of health and disease.
- Explain the utility and the limitations of case reports and case series.
- Describe the design features and the advantages and weaknesses of each of the following study designs: Cross-sectional studies, ecological studies, retrospective and prospective cohort studies, case control studies, and intervention studies
- Identify the study design when reading an article or abstract.
- Explain how different study designs can be applied to the same hypothesis to provide different and complementary information.