Discussion: Observational Study Designs

This type of suspected association between a risk factor (exposure) and a particular outcome (childhood asthma) can be evaluated using an observational study design. A relevant case-control study would match a group of controls (no asthma) with the case group (asthma diagnosis). Both groups would then be assessed on certain historical exposures like (a) family history; (b) early childhood respiratory infections; (c) secondhand smoke exposure; (d) urban residence (ozone); and (e) obesity. Measures might include interviews, surveys, and medical records. If results show the case group has a higher rate of exposure to a given risk factor, the researcher may conclude that exposure results in greater odds of asthma.

In any epidemiological study, the design and methodology used should be appropriate for that study and for the research question. It is important for researchers to understand the strengths and limitations of each of the study designs and methods. This gives them a better chance of correctly interpreting results and synthesizing them for use in developing and implementing evidence-based population health programs. For this Discussion, you will explore the strengths and limitations of various types of observational study designs and critique their appropriateness for specific studies.

To prepare:

• Review the different types of observational study designs presented in the Learning Resources: ecologic, cross-sectional, case-control, and cohort.
• Carefully examine the characteristics, strengths, and limitations of each design.
• Consider when it is appropriate to use each of the observational study designs.
• Consider how using observational study designs can lead to improvements in population health.
• By Day 1 of this week, you should have received a communication from your Instructor assigning you to a small group to review two specific articles. Review the two articles your group was assigned, with a critical eye toward the researchers’ use of study design and their selected methods. Although several students will be assigned the same articles, this is NOT a group project; please submit your Discussion posts individually. You will then have the opportunity to discuss and share your thoughts with your colleagues.

By Day 3 of Week 3

In your assigned group area:

Post a brief description of the two studies you were assigned, with a particular focus on the study design and methods. Then:

• Describe at least one strength and one limitation of each study’s design.
• Identify the population, data sources, and epidemiologic measures of association that the authors used.
• Finally, share your insights about the appropriateness of the design for the study. Do you agree with the researchers’ choice of design?
• Do you agree with the researchers’ conclusions? Justify your reasoning.

By Day 5 of Week 3

Post at least two substantive responses to peers in a different group who analyzed at least one different article in their initial post. Include information from the Learning Resources in your responses as appropriate. You may expand on each peer’s posting with additional insight and resources about study designs, ask a question to further the discussion, or offer polite disagreement or critique supported with evidence. You may also make a suggestion or comment that guides or facilitates the discussion. At least one of your response posts should address the applicability of observational studies for improving population health status.