Suppose that you have been hired by university student health services to design a case-control study to assess the following hypothesis among undergraduate students:
Irregular sleep patterns increase the risk of headaches.Be sure that your design addresses the following elements:
- Refine the study hypothesis so that it is as specific as possible and contains all elements of a “good” hypothesis.
- How will you identify and define the cases?
- Are there any exclusion criteria that you would apply?
- How will you sample from the underlying population for your “controls”?
- Who will you select as controls?
- How will you select them?
- How will you define the exposure of interest?
- How will you collect the information on exposure?
- What other information do you want to know about participants that may be related to the exposure of interest and/or the outcome (potential confounders)? Of these, what will you be able to collect and what will you be unable to collect?
- Which measures of disease frequency and association will you calculate?
- What are the strengths and limitations of your study?
- Which limitations could be removed by using a different study design?
- What other information would you like to know to design this study?
Expert Solution Preview
Introduction: As a medical professor, I have been tasked with designing a case-control study to assess the hypothesis that irregular sleep patterns increase the risk of headaches among undergraduate students.
Refined study hypothesis: The refined study hypothesis is that undergraduate students with irregular sleep patterns have a higher risk of experiencing headaches compared to those with regular sleep patterns.
Identification and definition of cases: Cases will be identified as undergraduate students who report experiencing headaches within the past 30 days. Exclusion criteria will be applied to exclude students who have a history of chronic headaches or have experienced a traumatic brain injury.
Sampling of controls: Controls will be sampled from the same undergraduate student population as the cases. Controls will be matched to cases based on age, gender, and college major.
Selection of controls: Controls will be selected randomly from the pool of eligible undergraduate students who have not reported experiencing headaches within the past 30 days.
Definition of exposure of interest: The exposure of interest is irregular sleep patterns. Information on exposure will be collected through self-reported responses to a questionnaire asking about sleep patterns over the past month.
Other relevant information: Other information that will be collected includes demographic data such as age, gender, and college major, as well as lifestyle factors such as caffeine intake and stress levels. Some potential confounding variables such as family history of headaches or history of other health conditions may also be collected.
Measures of disease frequency and association: Measures of disease frequency will include the proportion of cases and controls that report irregular sleep patterns. Measures of association will include odds ratios and confidence intervals.
Strengths and limitations of the study: The study design allows for the assessment of a specific hypothesis and the matching of controls to cases. However, limitations include potential recall bias and the inability to establish causation due to the case-control design. A different study design such as a cohort study could help overcome some of these limitations.
Additional information needed: Additional information needed includes sample size calculations, ethical considerations, and funding sources for the study.
